macros, vm, bytecode: add #[primop] await-style primop macro

Cargo.toml

@@ -2,41 +2,102 @@
 resolver = "3"
 members = [
   "fix",
-    "fix-abstract-vm",
-    "fix-builtins",
-    "fix-codegen",
-    "fix-common",
+  "fix-bytecode",
+  "fix-compiler",
   "fix-error",
-    "fix-ir",
-    "fix-primops",
+  "fix-lang",
+  "fix-macros",
+  "fix-runtime",
   "fix-vm",
 ]
 
-[profile.profiling]
-inherits = "release"
-debug = true
+[workspace.dependencies]
+bumpalo = {
+  version = "3.20",
+  features = [
+    "allocator-api2",
+    "boxed",
+    "collections",
+  ]
+}
+ere = "0.2"
+ghost-cell = "0.2"
+hashbrown = "0.17"
+num_enum = "0.7"
+rnix = "0.14"
+rowan = "0.16"
+smallvec = { version = "1.15", features = ["const_generics", "const_new"] }
+string-interner = "0.20"
+gc-arena = { version = "0.7", features = ["hashbrown", "smallvec"] }
+
+# https://emschwartz.me/your-clippy-config-should-be-stricter/
+# tombi: format.rules.table-keys-order.disabled = true
+[workspace.lints.clippy]
+# Don't Panic - prevent panics from unwraps and unsafe slicing or indexing
+string_slice = "warn"
+indexing_slicing = "warn"
+unwrap_used = "warn"
+panic = "warn"
+# WIP evaluator: several features are deliberately stubbed with todo!/unimplemented!
+todo = "allow"
+unimplemented = "allow"
+unreachable = "warn"
+get_unwrap = "warn"
+unwrap_in_result = "warn"
+unchecked_time_subtraction = "warn"
+panic_in_result_fn = "warn"
+# Optional - see post for caveats
+# expect_used = "warn"
+# arithmetic_side_effects = "warn"
+
+# Don't Fail Silently - prevent dropped futures and swallowed errors
+let_underscore_future = "warn"
+let_underscore_must_use = "warn"
+unused_result_ok = "warn"
+map_err_ignore = "warn"
+assertions_on_result_states = "warn"
+
+# Don't Do Bad Async Stuff - prevent deadlocks and concurrency bugs
+await_holding_lock = "warn"
+await_holding_refcell_ref = "warn"
+if_let_mutex = "warn"  # only relevant on editions before 2024
+large_futures = "warn"
+
+# Don't Do Unsafe Things with Memory
+mem_forget = "warn"
+undocumented_unsafe_blocks = "warn"
+multiple_unsafe_ops_per_block = "warn"
+unnecessary_safety_doc = "warn"
+unnecessary_safety_comment = "warn"
+
+# Don't Do Potentially Incorrect Things with Numbers
+float_cmp = "warn"
+float_cmp_const = "warn"
+lossy_float_literal = "warn"
+cast_sign_loss = "warn"
+invalid_upcast_comparisons = "warn"
+# Optional - these effectively force you to document numeric invariants
+# cast_possible_wrap = "warn"
+# cast_precision_loss = "warn"
+# cast_possible_truncation = "warn"
+
+# Don't Do Bad Things That are Easy to Avoid
+rc_mutex = "warn"
+debug_assert_with_mut_call = "warn"
+iter_not_returning_iterator = "warn"
+expl_impl_clone_on_copy = "warn"
+infallible_try_from = "warn"
+dbg_macro = "warn"
+
+# Don't `allow` Your Way Around These Lints - every suppression must be
+# a deliberate #[expect(..., reason = "…")] rather than a silent #[allow]
+allow_attributes = "warn"
+allow_attributes_without_reason = "warn"
 
 [profile.lto]
 inherits = "release"
 lto = true
 
-[workspace.dependencies]
-bumpalo = { version = "3.20", features = [
-    "allocator-api2",
-    "boxed",
-    "collections",
-] }
-ghost-cell = "0.2"
-hashbrown = "0.16"
-num_enum = "0.7.5"
-smallvec = { version = "1.15", features = ["const_new", "const_generics"] }
-ere = "0.2"
-string-interner = "0.19"
-rnix = "0.14"
-rowan = "0.16"
-likely_stable = "0.1"
-
-[workspace.dependencies.gc-arena]
-git = "https://github.com/kyren/gc-arena"
-rev = "75671ae03f53718357b741ed4027560f14e90836"
-features = ["allocator-api2", "hashbrown", "smallvec"]
+[profile.profiling]
+inherits = "release"
+debug = true

Justfile

@@ -14,22 +14,6 @@
 @evalr expr:
   cargo run --release -- eval --expr '{{expr}}'
 
-[no-exit-message]
-@repli:
-  cargo run --release --features inspector -- --inspect-brk 127.0.0.1:9229 repl
-
-[no-exit-message]
-@evali expr:
-  cargo run --release --features inspector -- --inspect-brk 127.0.0.1:9229 eval --expr '{{expr}}'
-
-[no-exit-message]
-@replp:
-  cargo run --release --features prof -- repl
-
-[no-exit-message]
-@evalp expr:
-  cargo run --release --features prof -- eval --expr '{{expr}}'
-
 [no-exit-message]
 [positional-arguments]
 @cg *args='':

clippy.toml

@@ -0,0 +1,5 @@
+allow-indexing-slicing-in-tests = true
+allow-panic-in-tests = true
+allow-unwrap-in-tests = true
+allow-expect-in-tests = true
+allow-dbg-in-tests = true

devShell.nix

@@ -0,0 +1,24 @@
+{ pkgs }:
+pkgs.mkShell {
+  packages = with pkgs; [
+    (fenix.latest.withComponents [
+      "cargo"
+      "clippy"
+      "rust-src"
+      "rustc"
+      "rustfmt"
+      "rust-analyzer"
+    ])
+    cargo-machete
+    cargo-bloat
+    cargo-expand
+    lldb
+    valgrind
+    kdePackages.kcachegrind
+    hyperfine
+    just
+    samply
+    tokei
+    tombi
+  ];
+}

fix-abstract-vm/src/bytecode_reader.rs

@@ -1,142 +0,0 @@
-#![allow(dead_code)]
-
-use fix_codegen::OperandType;
-use fix_common::StringId;
-use num_enum::TryFromPrimitive;
-use string_interner::Symbol as _;
-
-use crate::{OperandData, VmRuntimeCtx};
-
-pub struct BytecodeReader<'a> {
-    bytecode: &'a [u8],
-    pc: usize,
-    inst_start_pc: usize,
-}
-
-impl<'a> BytecodeReader<'a> {
-    pub fn new(bytecode: &'a [u8], pc: usize) -> Self {
-        Self {
-            bytecode,
-            pc,
-            inst_start_pc: pc,
-        }
-    }
-
-    #[inline(always)]
-    pub fn from_after_op(bytecode: &'a [u8], inst_start_pc: usize) -> Self {
-        Self {
-            bytecode,
-            pc: inst_start_pc + 1,
-            inst_start_pc,
-        }
-    }
-
-    #[inline(always)]
-    #[cfg_attr(debug_assertions, track_caller)]
-    fn read_array<const N: usize>(&mut self) -> [u8; N] {
-        let ret = self.bytecode[self.pc..self.pc + N]
-            .try_into()
-            .expect("read_array failed");
-        self.pc += N;
-        ret
-    }
-
-    #[inline(always)]
-    pub fn read_op(&mut self) -> fix_codegen::Op {
-        use fix_codegen::Op;
-        self.inst_start_pc = self.pc;
-        let byte = self.bytecode[self.pc];
-        if !likely_stable::likely((0..Op::Illegal as u8).contains(&byte)) {
-            panic!("unknown opcode: {byte:#04x}")
-        }
-        self.pc += 1;
-        unsafe { std::mem::transmute::<u8, Op>(byte) }
-    }
-
-    #[inline(always)]
-    pub fn read_u8(&mut self) -> u8 {
-        let val = self.bytecode[self.pc];
-        self.pc += 1;
-        val
-    }
-
-    #[inline(always)]
-    pub fn read_u16(&mut self) -> u16 {
-        u16::from_le_bytes(self.read_array())
-    }
-
-    #[inline(always)]
-    pub fn read_u32(&mut self) -> u32 {
-        u32::from_le_bytes(self.read_array())
-    }
-
-    #[inline(always)]
-    pub fn read_i32(&mut self) -> i32 {
-        i32::from_le_bytes(self.read_array())
-    }
-
-    #[inline(always)]
-    pub fn read_i64(&mut self) -> i64 {
-        i64::from_le_bytes(self.read_array())
-    }
-
-    #[inline(always)]
-    pub fn read_f64(&mut self) -> f64 {
-        f64::from_le_bytes(self.read_array())
-    }
-
-    #[inline(always)]
-    pub fn read_string_id(&mut self) -> StringId {
-        let raw = self.read_u32();
-        #[allow(clippy::unwrap_used)]
-        StringId(string_interner::symbol::SymbolU32::try_from_usize(raw as usize).unwrap())
-    }
-
-    #[inline(always)]
-    pub fn read_operand_data<C: VmRuntimeCtx>(&mut self, ctx: &C) -> OperandData {
-        let tag = self.read_u8();
-        let Ok(ty) = OperandType::try_from_primitive(tag)
-            .map_err(|err| panic!("unknown operand tag: {:#04x}", err.number));
-        match ty {
-            OperandType::Const => {
-                let id = self.read_u32();
-                OperandData::Const(ctx.get_const(id))
-            }
-            OperandType::BigInt => {
-                let val = self.read_i64();
-                OperandData::BigInt(val)
-            }
-            OperandType::Local => {
-                let layer = self.read_u8();
-                let idx = self.read_u32();
-                OperandData::Local { layer, idx }
-            }
-            OperandType::BuiltinConst => {
-                let id = self.read_string_id();
-                OperandData::BuiltinConst(id)
-            }
-            OperandType::Builtins => OperandData::Builtins,
-            OperandType::ReplBinding => {
-                let id = self.read_string_id();
-                OperandData::ReplBinding(id)
-            }
-            OperandType::ScopedImportBinding => {
-                let slot_id = self.read_u32();
-                let name = self.read_string_id();
-                OperandData::ScopedImportBinding { slot_id, name }
-            }
-        }
-    }
-
-    pub fn pc(&self) -> usize {
-        self.pc
-    }
-
-    pub fn set_pc(&mut self, pc: usize) {
-        self.pc = pc;
-    }
-
-    pub fn inst_start_pc(&self) -> usize {
-        self.inst_start_pc
-    }
-}

fix-builtins/Cargo.toml

@@ -1,8 +0,0 @@
-[package]
-name = "fix-builtins"
-version = "0.1.0"
-edition = "2024"
-
-[dependencies]
-num_enum = { workspace = true }
-gc-arena = { workspace = true }

fix-builtins/src/lib.rs

@@ -1,399 +0,0 @@
-use gc_arena::Collect;
-use num_enum::TryFromPrimitive;
-
-macro_rules! define_builtins {
-    ($(($name:literal, $variant:ident, $arity:expr)),* $(,)?) => {
-        /// Builtin function registry.
-        /// Array index IS the PrimOp id. (name, arity) pairs.
-        pub const BUILTINS: &[(&str, u8)] = &[
-            $(($name, $arity),)*
-        ];
-
-        #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, TryFromPrimitive, Collect)]
-        #[repr(u8)]
-        #[collect(require_static)]
-        pub enum BuiltinId {
-            $($variant,)*
-        }
-    };
-}
-
-define_builtins! {
-    ("abort",                    Abort,                    1),
-    ("__add",                      Add,                      2),
-    ("__addErrorContext",          AddErrorContext,           2),
-    ("__all",                      All,                      2),
-    ("__any",                      Any,                      2),
-    ("__appendContext",            AppendContext,             2),
-    ("__attrNames",                AttrNames,                1),
-    ("__attrValues",               AttrValues,               1),
-    ("baseNameOf",               BaseNameOf,               1),
-    ("__bitAnd",                   BitAnd,                   2),
-    ("__bitOr",                    BitOr,                    2),
-    ("__bitXor",                   BitXor,                   2),
-    ("break",                    Break,                    1),
-    ("__catAttrs",                 CatAttrs,                 2),
-    ("__ceil",                     Ceil,                     1),
-    ("__compareVersions",          CompareVersions,          2),
-    ("__concatLists",              ConcatLists,              1),
-    ("__concatMap",                ConcatMap,                2),
-    ("__concatStringsSep",         ConcatStringsSep,         2),
-    ("__convertHash",              ConvertHash,              1),
-    ("__deepSeq",                  DeepSeq,                  2),
-    ("derivation",               Derivation,               1),
-    ("derivationStrict",         DerivationStrict,         1),
-    ("dirOf",                    DirOf,                    1),
-    ("__div",                      Div,                      2),
-    ("__elem",                     Elem,                     2),
-    ("__elemAt",                   ElemAt,                   2),
-    ("fetchGit",                 FetchGit,                 1),
-    ("fetchMercurial",           FetchMercurial,           1),
-    ("fetchTarball",             FetchTarball,             1),
-    ("fetchTree",                FetchTree,                1),
-    ("__fetchurl",                 FetchUrl,                 1),
-    ("__filter",                   Filter,                   2),
-    ("__filterSource",             FilterSource,             2),
-    ("__findFile",                 FindFile,                 2),
-    ("__floor",                    Floor,                    1),
-    ("__foldl'",                   FoldlStrict,              3),
-    ("__fromJSON",                 FromJSON,                 1),
-    ("fromTOML",                 FromTOML,                 1),
-    ("__functionArgs",             FunctionArgs,             1),
-    ("__genList",                  GenList,                  2),
-    ("__genericClosure",           GenericClosure,           1),
-    ("__getAttr",                  GetAttr,                  2),
-    ("__getContext",               GetContext,               1),
-    ("__getEnv",                   GetEnv,                   1),
-    ("__groupBy",                  GroupBy,                  2),
-    ("__hasAttr",                  HasAttr,                  2),
-    ("__hasContext",               HasContext,               1),
-    ("__hashFile",                 HashFile,                 2),
-    ("__hashString",               HashString,               2),
-    ("__head",                     Head,                     1),
-    ("import",                   Import,                   1),
-    ("__intersectAttrs",           IntersectAttrs,           2),
-    ("__isAttrs",                  IsAttrs,                  1),
-    ("__isBool",                   IsBool,                   1),
-    ("__isFloat",                  IsFloat,                  1),
-    ("__isFunction",               IsFunction,               1),
-    ("__isInt",                    IsInt,                    1),
-    ("__isList",                   IsList,                   1),
-    ("isNull",                   IsNull,                   1),
-    ("__isPath",                   IsPath,                   1),
-    ("__isString",                 IsString,                 1),
-    ("__length",                   Length,                   1),
-    ("__lessThan",                 LessThan,                 2),
-    ("__listToAttrs",              ListToAttrs,              1),
-    ("map",                      Map,                      2),
-    ("__mapAttrs",                 MapAttrs,                 2),
-    ("__match",                    Match,                    2),
-    ("__mul",                      Mul,                      2),
-    ("__parseDrvName",             ParseDrvName,             1),
-    ("__partition",                Partition,                2),
-    ("__path",                     Path,                     1),
-    ("__pathExists",               PathExists,               1),
-    ("placeholder",              Placeholder,              1),
-    ("__readDir",                  ReadDir,                  1),
-    ("__readFile",                 ReadFile,                 1),
-    ("__readFileType",             ReadFileType,             1),
-    ("removeAttrs",              RemoveAttrs,              2),
-    ("__replaceStrings",           ReplaceStrings,           3),
-    ("scopedImport",             ScopedImport,             2),
-    ("__seq",                      Seq,                      2),
-    ("__sort",                     Sort,                     2),
-    ("__split",                    Split,                    2),
-    ("__splitVersion",             SplitVersion,             1),
-    ("__storePath",                StorePath,                1),
-    ("__stringLength",             StringLength,             1),
-    ("__sub",                      Sub,                      2),
-    ("__substring",                Substring,                3),
-    ("__tail",                     Tail,                     1),
-    ("throw",                    Throw,                    1),
-    ("__toFile",                   ToFile,                   2),
-    ("__toJSON",                   ToJSON,                   1),
-    ("__toPath",                   ToPath,                   1),
-    ("toString",                 ToString,                 1),
-    ("__toXML",                    ToXML,                    1),
-    ("__trace",                    Trace,                    2),
-    ("__tryEval",                  TryEval,                  1),
-    ("__typeOf",                   TypeOf,                   1),
-    ("__unsafeDiscardStringContext", UnsafeDiscardStringContext, 1),
-    ("__unsafeDiscardOutputDependency", UnsafeDiscardOutputDependency, 1),
-    ("__unsafeGetAttrPos",         UnsafeGetAttrPos,         2),
-    ("__warn",                     Warn,                     2),
-    ("__zipAttrsWith",             ZipAttrsWith,             2),
-}
-
-#[repr(u8)]
-#[derive(Debug, Clone, Copy, Hash, PartialEq, Eq)]
-pub enum PrimOpPhase {
-    Abort,
-    Add,
-    AddErrorContext,
-    All,
-    Any,
-    AppendContext,
-    AttrNames,
-    AttrValues,
-    BaseNameOf,
-    BitAnd,
-    BitOr,
-    BitXor,
-    Break,
-    CatAttrs,
-    Ceil,
-    CompareVersions,
-    ConcatLists,
-    ConcatMap,
-    ConcatStringsSep,
-    ConvertHash,
-
-    DeepSeq,
-    DeepSeqPush,
-    DeepSeqLoop,
-
-    Derivation,
-    DerivationStrict,
-    DirOf,
-    Div,
-    Elem,
-    ElemAt,
-    FetchGit,
-    FetchMercurial,
-    FetchTarball,
-    FetchTree,
-    FetchUrl,
-
-    FilterForceList,
-    FilterCallPred,
-    FilterCheck,
-
-    FilterSource,
-    FindFile,
-    Floor,
-    FoldlStrict,
-    FoldlStrictEmpty,
-    FoldlStrictCall1,
-    FoldlStrictCall2,
-    FoldlStrictUpdate,
-    FromJSON,
-    FromTOML,
-    FunctionArgs,
-    GenList,
-    GenericClosure,
-    GetAttr,
-    GetContext,
-    GetEnv,
-    GroupBy,
-    HasAttr,
-    HasContext,
-    HashFile,
-    HashString,
-    Head,
-    Import,
-    IntersectAttrs,
-    IsAttrs,
-    IsBool,
-    IsFloat,
-    IsFunction,
-    IsInt,
-    IsList,
-    IsNull,
-    IsPath,
-    IsString,
-    Length,
-    LessThan,
-    ListToAttrs,
-    Map,
-    MapAttrs,
-    Match,
-    Mul,
-    ParseDrvName,
-    Partition,
-    Path,
-    PathExists,
-    Placeholder,
-    ReadDir,
-    ReadFile,
-    ReadFileType,
-    RemoveAttrs,
-    ReplaceStrings,
-    ScopedImport,
-    Seq,
-    Sort,
-    Split,
-    SplitVersion,
-    StorePath,
-    StringLength,
-    Sub,
-    Substring,
-    Tail,
-    Throw,
-    ToFile,
-    ToJSON,
-    ToPath,
-    ToString,
-    ToXML,
-    Trace,
-    TryEval,
-    TypeOf,
-    UnsafeDiscardStringContext,
-    UnsafeGetAttrPos,
-    Warn,
-    ZipAttrsWith,
-
-    ForceResultShallow,
-    ForceResultShallowPush,
-    ForceResultShallowLoop,
-    ForceResultDeepFinish,
-
-    EqStep,
-    EqForce,
-
-    // TODO: split into separate enums
-    CallPattern,
-    CallFunctor1,
-    CallFunctor2,
-
-    ImportFinalize,
-    ScopedImportFinalize,
-
-    AppendContextLoop,
-    AppendContextEntryForced,
-    AppendContextOutputsForced,
-    AppendContextOutputElementLoop,
-    AppendContextOutputElementForced,
-
-    UnsafeDiscardOutputDependency,
-
-    Illegal,
-}
-
-impl TryFrom<u8> for PrimOpPhase {
-    type Error = u8;
-    fn try_from(value: u8) -> Result<Self, Self::Error> {
-        if (0..Self::Illegal as u8).contains(&value) {
-            Ok(unsafe { std::mem::transmute::<u8, Self>(value) })
-        } else {
-            Err(value)
-        }
-    }
-}
-
-impl BuiltinId {
-    #[inline(always)]
-    pub fn entry_phase(self) -> PrimOpPhase {
-        use BuiltinId::*;
-        match self {
-            Abort => PrimOpPhase::Abort,
-            Add => PrimOpPhase::Add,
-            AddErrorContext => PrimOpPhase::AddErrorContext,
-            All => PrimOpPhase::All,
-            Any => PrimOpPhase::Any,
-            AppendContext => PrimOpPhase::AppendContext,
-            AttrNames => PrimOpPhase::AttrNames,
-            AttrValues => PrimOpPhase::AttrValues,
-            BaseNameOf => PrimOpPhase::BaseNameOf,
-            BitAnd => PrimOpPhase::BitAnd,
-            BitOr => PrimOpPhase::BitOr,
-            BitXor => PrimOpPhase::BitXor,
-            Break => PrimOpPhase::Break,
-            CatAttrs => PrimOpPhase::CatAttrs,
-            Ceil => PrimOpPhase::Ceil,
-            CompareVersions => PrimOpPhase::CompareVersions,
-            ConcatLists => PrimOpPhase::ConcatLists,
-            ConcatMap => PrimOpPhase::ConcatMap,
-            ConcatStringsSep => PrimOpPhase::ConcatStringsSep,
-            ConvertHash => PrimOpPhase::ConvertHash,
-            DeepSeq => PrimOpPhase::DeepSeq,
-            Derivation => PrimOpPhase::Derivation,
-            DerivationStrict => PrimOpPhase::DerivationStrict,
-            DirOf => PrimOpPhase::DirOf,
-            Div => PrimOpPhase::Div,
-            Elem => PrimOpPhase::Elem,
-            ElemAt => PrimOpPhase::ElemAt,
-            FetchGit => PrimOpPhase::FetchGit,
-            FetchMercurial => PrimOpPhase::FetchMercurial,
-            FetchTarball => PrimOpPhase::FetchTarball,
-            FetchTree => PrimOpPhase::FetchTree,
-            FetchUrl => PrimOpPhase::FetchUrl,
-            Filter => PrimOpPhase::FilterForceList,
-            FilterSource => PrimOpPhase::FilterSource,
-            FindFile => PrimOpPhase::FindFile,
-            Floor => PrimOpPhase::Floor,
-            FoldlStrict => PrimOpPhase::FoldlStrict,
-            FromJSON => PrimOpPhase::FromJSON,
-            FromTOML => PrimOpPhase::FromTOML,
-            FunctionArgs => PrimOpPhase::FunctionArgs,
-            GenList => PrimOpPhase::GenList,
-            GenericClosure => PrimOpPhase::GenericClosure,
-            GetAttr => PrimOpPhase::GetAttr,
-            GetContext => PrimOpPhase::GetContext,
-            GetEnv => PrimOpPhase::GetEnv,
-            GroupBy => PrimOpPhase::GroupBy,
-            HasAttr => PrimOpPhase::HasAttr,
-            HasContext => PrimOpPhase::HasContext,
-            HashFile => PrimOpPhase::HashFile,
-            HashString => PrimOpPhase::HashString,
-            Head => PrimOpPhase::Head,
-            Import => PrimOpPhase::Import,
-            IntersectAttrs => PrimOpPhase::IntersectAttrs,
-            IsAttrs => PrimOpPhase::IsAttrs,
-            IsBool => PrimOpPhase::IsBool,
-            IsFloat => PrimOpPhase::IsFloat,
-            IsFunction => PrimOpPhase::IsFunction,
-            IsInt => PrimOpPhase::IsInt,
-            IsList => PrimOpPhase::IsList,
-            IsNull => PrimOpPhase::IsNull,
-            IsPath => PrimOpPhase::IsPath,
-            IsString => PrimOpPhase::IsString,
-            Length => PrimOpPhase::Length,
-            LessThan => PrimOpPhase::LessThan,
-            ListToAttrs => PrimOpPhase::ListToAttrs,
-            Map => PrimOpPhase::Map,
-            MapAttrs => PrimOpPhase::MapAttrs,
-            Match => PrimOpPhase::Match,
-            Mul => PrimOpPhase::Mul,
-            ParseDrvName => PrimOpPhase::ParseDrvName,
-            Partition => PrimOpPhase::Partition,
-            Path => PrimOpPhase::Path,
-            PathExists => PrimOpPhase::PathExists,
-            Placeholder => PrimOpPhase::Placeholder,
-            ReadDir => PrimOpPhase::ReadDir,
-            ReadFile => PrimOpPhase::ReadFile,
-            ReadFileType => PrimOpPhase::ReadFileType,
-            RemoveAttrs => PrimOpPhase::RemoveAttrs,
-            ReplaceStrings => PrimOpPhase::ReplaceStrings,
-            ScopedImport => PrimOpPhase::ScopedImport,
-            Seq => PrimOpPhase::Seq,
-            Sort => PrimOpPhase::Sort,
-            Split => PrimOpPhase::Split,
-            SplitVersion => PrimOpPhase::SplitVersion,
-            StorePath => PrimOpPhase::StorePath,
-            StringLength => PrimOpPhase::StringLength,
-            Sub => PrimOpPhase::Sub,
-            Substring => PrimOpPhase::Substring,
-            Tail => PrimOpPhase::Tail,
-            Throw => PrimOpPhase::Throw,
-            ToFile => PrimOpPhase::ToFile,
-            ToJSON => PrimOpPhase::ToJSON,
-            ToPath => PrimOpPhase::ToPath,
-            ToString => PrimOpPhase::ToString,
-            ToXML => PrimOpPhase::ToXML,
-            Trace => PrimOpPhase::Trace,
-            TryEval => PrimOpPhase::TryEval,
-            TypeOf => PrimOpPhase::TypeOf,
-            UnsafeDiscardStringContext => PrimOpPhase::UnsafeDiscardStringContext,
-            UnsafeDiscardOutputDependency => PrimOpPhase::UnsafeDiscardOutputDependency,
-            UnsafeGetAttrPos => PrimOpPhase::UnsafeGetAttrPos,
-            Warn => PrimOpPhase::Warn,
-            ZipAttrsWith => PrimOpPhase::ZipAttrsWith,
-        }
-    }
-}
-
-impl PrimOpPhase {
-    pub fn ip(self) -> u32 {
-        self as u32 * 2
-    }
-}

fix-bytecode/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "fix-bytecode"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+colored = "3.1.1"
+num_enum = { workspace = true }
+string-interner = { workspace = true }
+
+fix-lang = { path = "../fix-lang" }
+
+[lints]
+workspace = true

fix-bytecode/src/disassembler.rs

@@ -1,10 +1,8 @@
 use std::fmt::Write;
 
-use colored::Colorize;
-use fix_builtins::BuiltinId;
-use num_enum::TryFromPrimitive;
+use colored::Colorize as _;
 
-use crate::{InstructionPtr, Op, OperandType};
+use crate::{BytecodeReader, Continuation, InstructionPtr, Op};
 
 pub trait DisassemblerContext {
     fn resolve_string(&self, id: u32) -> &str;
@@ -12,99 +10,15 @@ pub trait DisassemblerContext {
 }
 
 pub struct Disassembler<'a, Ctx> {
-    code: &'a [u8],
+    reader: BytecodeReader<'a>,
     ctx: &'a Ctx,
-    pc: usize,
 }
 
 impl<'a, Ctx: DisassemblerContext> Disassembler<'a, Ctx> {
     pub fn new(ip: InstructionPtr, ctx: &'a Ctx) -> Self {
         Self {
-            code: ctx.get_code(),
+            reader: BytecodeReader::new(ctx.get_code(), ip.0),
             ctx,
-            pc: ip.0,
-        }
-    }
-
-    #[inline(always)]
-    fn read_u8(&mut self) -> u8 {
-        let b = self.code[self.pc];
-        self.pc += 1;
-        b
-    }
-
-    #[inline(always)]
-    fn read_u16(&mut self) -> u16 {
-        let bytes = self.code[self.pc..self.pc + 2]
-            .try_into()
-            .expect("no enough bytes");
-        self.pc += 2;
-        u16::from_le_bytes(bytes)
-    }
-
-    #[inline(always)]
-    fn read_u32(&mut self) -> u32 {
-        let bytes = self.code[self.pc..self.pc + 4]
-            .try_into()
-            .expect("no enough bytes");
-        self.pc += 4;
-        u32::from_le_bytes(bytes)
-    }
-
-    #[inline(always)]
-    fn read_i32(&mut self) -> i32 {
-        let bytes = self.code[self.pc..self.pc + 4]
-            .try_into()
-            .expect("no enough bytes");
-        self.pc += 4;
-        i32::from_le_bytes(bytes)
-    }
-
-    #[inline(always)]
-    fn read_i64(&mut self) -> i64 {
-        let bytes = self.code[self.pc..self.pc + 8]
-            .try_into()
-            .expect("no enough bytes");
-        self.pc += 8;
-        i64::from_le_bytes(bytes)
-    }
-
-    #[inline(always)]
-    fn read_f64(&mut self) -> f64 {
-        let bytes = self.code[self.pc..self.pc + 8]
-            .try_into()
-            .expect("no enough bytes");
-        self.pc += 8;
-        f64::from_le_bytes(bytes)
-    }
-
-    #[inline(always)]
-    fn read_operand_data(&mut self) {
-        use OperandType::*;
-        let tag = self.read_u8();
-        let ty = OperandType::try_from_primitive(tag).expect("invalid operand type");
-        match ty {
-            Const => {
-                self.read_u32();
-            }
-            BigInt => {
-                self.read_i64();
-            }
-            Local => {
-                self.read_u8();
-                self.read_u32();
-            }
-            BuiltinConst => {
-                self.read_u32();
-            }
-            Builtins => {}
-            ReplBinding => {
-                self.read_u32();
-            }
-            ScopedImportBinding => {
-                self.read_u32();
-                self.read_u32();
-            }
         }
     }
 
@@ -116,6 +30,11 @@ impl<'a, Ctx: DisassemblerContext> Disassembler<'a, Ctx> {
         self.disassemble_impl(true)
     }
 
+    #[expect(
+        clippy::let_underscore_must_use,
+        clippy::indexing_slicing,
+        reason = "disassembler operates on well-formed bytecode; writes target an in-memory String via fmt::Write, which is infallible"
+    )]
     fn disassemble_impl(&mut self, color: bool) -> String {
         let mut out = String::new();
         if color {
@@ -124,24 +43,24 @@ impl<'a, Ctx: DisassemblerContext> Disassembler<'a, Ctx> {
                 out,
                 "{} {}",
                 "Length:".white(),
-                format!("{} bytes", self.code.len()).cyan()
+                format!("{} bytes", self.reader.len()).cyan()
             );
         } else {
             let _ = writeln!(out, "=== Bytecode Disassembly ===");
-            let _ = writeln!(out, "Length: {} bytes", self.code.len());
+            let _ = writeln!(out, "Length: {} bytes", self.reader.len());
         }
 
-        while self.pc < self.code.len() {
-            let start_pos = self.pc;
-            let op_byte = self.read_u8();
+        while self.reader.pc() < self.reader.len() {
+            let start_pos = self.reader.pc();
+            let op_byte = self.reader.read_u8();
             let (mnemonic, args) = self.decode_instruction(op_byte, start_pos);
 
-            let bytes_slice = &self.code[start_pos + 1..self.pc];
+            let bytes_slice = &self.reader[start_pos + 1..self.reader.pc()];
             let mut chunks = bytes_slice.chunks(4);
 
             let first_chunk = chunks.next().unwrap_or(&[]);
             let bytes_str = {
-                let mut temp = format!("{:02x}", self.code[start_pos]);
+                let mut temp = format!("{:02x}", self.reader[start_pos]);
                 for b in first_chunk {
                     let _ = write!(&mut temp, " {:02x}", b);
                 }
@@ -201,31 +120,36 @@ impl<'a, Ctx: DisassemblerContext> Disassembler<'a, Ctx> {
         out
     }
 
+    #[expect(
+        clippy::let_underscore_must_use,
+        clippy::cast_sign_loss,
+        reason = "disassembler operates on well-formed bytecode; jump targets are valid non-negative PCs and writes to String are infallible"
+    )]
     fn decode_instruction(&mut self, op_byte: u8, current_pc: usize) -> (&'static str, String) {
-        let op = Op::try_from_primitive(op_byte).expect("invalid op code");
+        let op = Op::try_from(op_byte).expect("invalid op code");
 
         match op {
             Op::PushSmi => {
-                let val = self.read_i32();
+                let val = self.reader.read_i32();
                 ("PushSmi", format!("{}", val))
             }
             Op::PushBigInt => {
-                let val = self.read_i64();
+                let val = self.reader.read_i64();
                 ("PushBigInt", format!("{}", val))
             }
             Op::PushFloat => {
-                let val = self.read_f64();
+                let val = self.reader.read_f64();
                 ("PushFloat", format!("{}", val))
             }
             Op::PushString => {
-                let idx = self.read_u32();
+                let idx = self.reader.read_u32();
                 let s = self.ctx.resolve_string(idx);
                 let len = s.len();
                 let mut s_fmt = format!("{:?}", s);
                 if s_fmt.len() > 60 {
                     s_fmt.truncate(57);
-                    #[allow(clippy::unwrap_used)]
-                    write!(s_fmt, "...\" (total {len} bytes)").unwrap();
+                    write!(s_fmt, "...\" (total {len} bytes)")
+                        .expect("writing to String is infallible");
                 }
                 ("PushString", format!("@{} {}", idx, s_fmt))
             }
@@ -234,38 +158,38 @@ impl<'a, Ctx: DisassemblerContext> Disassembler<'a, Ctx> {
             Op::PushFalse => ("PushFalse", String::new()),
 
             Op::LoadLocal => {
-                let idx = self.read_u32();
+                let idx = self.reader.read_u32();
                 ("LoadLocal", format!("[{}]", idx))
             }
             Op::LoadOuter => {
-                let depth = self.read_u8();
-                let idx = self.read_u32();
+                let depth = self.reader.read_u8();
+                let idx = self.reader.read_u32();
                 ("LoadOuter", format!("depth={} [{}]", depth, idx))
             }
             Op::StoreLocal => {
-                let idx = self.read_u32();
+                let idx = self.reader.read_u32();
                 ("StoreLocal", format!("[{}]", idx))
             }
             Op::AllocLocals => {
-                let count = self.read_u32();
+                let count = self.reader.read_u32();
                 ("AllocLocals", format!("count={}", count))
             }
 
             Op::MakeThunk => {
-                let offset = self.read_u32();
+                let offset = self.reader.read_u32();
                 ("MakeThunk", format!("-> {:04x}", offset))
             }
             Op::MakeClosure => {
-                let offset = self.read_u32();
-                let slots = self.read_u32();
+                let offset = self.reader.read_u32();
+                let slots = self.reader.read_u32();
                 ("MakeClosure", format!("-> {:04x} slots={}", offset, slots))
             }
             Op::MakePatternClosure => {
-                let offset = self.read_u32();
-                let slots = self.read_u32();
-                let req_count = self.read_u16();
-                let opt_count = self.read_u16();
-                let ellipsis = self.read_u8() != 0;
+                let offset = self.reader.read_u32();
+                let slots = self.reader.read_u32();
+                let req_count = self.reader.read_u16();
+                let opt_count = self.reader.read_u16();
+                let ellipsis = self.reader.read_u8() != 0;
 
                 let mut arg_str = format!(
                     "-> {:04x} slots={} req={} opt={} ...={})",
@@ -274,18 +198,18 @@ impl<'a, Ctx: DisassemblerContext> Disassembler<'a, Ctx> {
 
                 arg_str.push_str(" Args=[");
                 for _ in 0..req_count {
-                    let idx = self.read_u32();
+                    let idx = self.reader.read_u32();
                     arg_str.push_str(&format!("Req({}) ", self.ctx.resolve_string(idx)));
                 }
                 for _ in 0..opt_count {
-                    let idx = self.read_u32();
+                    let idx = self.reader.read_u32();
                     arg_str.push_str(&format!("Opt({}) ", self.ctx.resolve_string(idx)));
                 }
 
                 let total_args = req_count + opt_count;
                 for _ in 0..total_args {
-                    let _name_idx = self.read_u32();
-                    let _span_id = self.read_u32();
+                    let _name_idx = self.reader.read_u32();
+                    let _span_id = self.reader.read_u32();
                 }
                 arg_str.push(']');
 
@@ -293,31 +217,32 @@ impl<'a, Ctx: DisassemblerContext> Disassembler<'a, Ctx> {
             }
 
             Op::Call => {
-                self.read_operand_data();
+                let _ = self.reader.read_operand_data();
                 ("Call", "arg=?".into())
             }
-            Op::DispatchPrimOp => {
-                let id = BuiltinId::try_from_primitive(self.read_u8()).expect("invalid builtin id");
-                ("DispatchPrimOp", format!("id={id:?}"))
+            Op::DispatchCont => {
+                let phase =
+                    Continuation::try_from(self.reader.read_u8()).expect("invalid primop phase");
+                ("DispatchPrimOp", format!("phase={phase:?}"))
             }
 
             Op::MakeAttrs => {
-                let static_count = self.read_u32();
-                let dynamic_count = self.read_u32();
+                let static_count = self.reader.read_u32();
+                let dynamic_count = self.reader.read_u32();
                 let mut args = format!("static={} dynamic={}", static_count, dynamic_count);
 
                 for _ in 0..static_count {
-                    let key_id = self.read_u32();
+                    let key_id = self.reader.read_u32();
                     let _ = write!(args, " [{}={}", self.ctx.resolve_string(key_id), key_id);
-                    self.read_operand_data();
-                    let _span_id = self.read_u32();
+                    let _ = self.reader.read_operand_data();
+                    let _span_id = self.reader.read_u32();
                     args.push(']');
                 }
 
                 for _ in 0..dynamic_count {
                     let _ = write!(args, " [dyn");
-                    self.read_operand_data();
-                    let _span_id = self.read_u32();
+                    let _ = self.reader.read_operand_data();
+                    let _span_id = self.reader.read_u32();
                     args.push(']');
                 }
 
@@ -326,31 +251,31 @@ impl<'a, Ctx: DisassemblerContext> Disassembler<'a, Ctx> {
             Op::MakeEmptyAttrs => ("MakeEmptyAttrs", String::new()),
 
             Op::SelectStatic => {
-                let span_id = self.read_u32();
-                let key_id = self.read_u32();
+                let span_id = self.reader.read_u32();
+                let key_id = self.reader.read_u32();
                 (
                     "SelectStatic",
                     format!("key={} span={}", self.ctx.resolve_string(key_id), span_id),
                 )
             }
             Op::SelectDynamic => {
-                let span_id = self.read_u32();
+                let span_id = self.reader.read_u32();
                 ("SelectDynamic", format!("span={}", span_id))
             }
             Op::HasAttrPathStatic => {
-                let span_id = self.read_u32();
-                let key_id = self.read_u32();
+                let span_id = self.reader.read_u32();
+                let key_id = self.reader.read_u32();
                 (
                     "HasAttrPathStatic",
                     format!("key={} span={}", self.ctx.resolve_string(key_id), span_id),
                 )
             }
             Op::HasAttrPathDynamic => {
-                let span_id = self.read_u32();
+                let span_id = self.reader.read_u32();
                 ("HasAttrPathDynamic", format!("span={}", span_id))
             }
             Op::HasAttrStatic => {
-                let key_id = self.read_u32();
+                let key_id = self.reader.read_u32();
                 (
                     "HasAttrStatic",
                     format!("key={}", self.ctx.resolve_string(key_id)),
@@ -359,7 +284,7 @@ impl<'a, Ctx: DisassemblerContext> Disassembler<'a, Ctx> {
             Op::HasAttrDynamic => ("HasAttrDynamic", String::new()),
             Op::HasAttrResolve => ("HasAttrResolve", String::new()),
             Op::JumpIfSelectSucceeded => {
-                let offset = self.read_i32();
+                let offset = self.reader.read_i32();
                 let target = (current_pc as isize + 1 + 4 + offset as isize) as usize;
                 (
                     "JumpIfSelectSucceeded",
@@ -367,7 +292,7 @@ impl<'a, Ctx: DisassemblerContext> Disassembler<'a, Ctx> {
                 )
             }
             Op::JumpIfSelectFailed => {
-                let offset = self.read_i32();
+                let offset = self.reader.read_i32();
                 let target = (current_pc as isize + 1 + 4 + offset as isize) as usize;
                 (
                     "JumpIfSelectFailed",
@@ -376,9 +301,9 @@ impl<'a, Ctx: DisassemblerContext> Disassembler<'a, Ctx> {
             }
 
             Op::MakeList => {
-                let count = self.read_u32();
+                let count = self.reader.read_u32();
                 for _ in 0..count {
-                    self.read_operand_data();
+                    let _ = self.reader.read_operand_data();
                 }
                 ("MakeList", format!("size={}", count))
             }
@@ -400,7 +325,7 @@ impl<'a, Ctx: DisassemblerContext> Disassembler<'a, Ctx> {
             Op::OpNot => ("OpNot", String::new()),
 
             Op::JumpIfFalse => {
-                let offset = self.read_i32();
+                let offset = self.reader.read_i32();
                 let target = (current_pc as isize + 1 + 4 + offset as isize) as usize;
                 (
                     "JumpIfFalse",
@@ -408,55 +333,55 @@ impl<'a, Ctx: DisassemblerContext> Disassembler<'a, Ctx> {
                 )
             }
             Op::JumpIfTrue => {
-                let offset = self.read_i32();
+                let offset = self.reader.read_i32();
                 let target = (current_pc as isize + 1 + 4 + offset as isize) as usize;
                 ("JumpIfTrue", format!("-> {:04x} offset={}", target, offset))
             }
             Op::Jump => {
-                let offset = self.read_i32();
+                let offset = self.reader.read_i32();
                 let target = (current_pc as isize + 1 + 4 + offset as isize) as usize;
                 ("Jump", format!("-> {:04x} offset={}", target, offset))
             }
 
             Op::ConcatStrings => {
-                let count = self.read_u16();
-                let force = self.read_u8();
+                let count = self.reader.read_u16();
+                let force = self.reader.read_u8();
                 ("ConcatStrings", format!("count={} force={}", count, force))
             }
             Op::CoerceToString => ("CoerceToString", String::new()),
             Op::ResolvePath => {
-                let dir_id = self.read_u32();
+                let dir_id = self.reader.read_u32();
                 let dir = self.ctx.resolve_string(dir_id);
                 ("ResolvePath", format!("dir={:?}", dir))
             }
             Op::Assert => {
-                let raw_idx = self.read_u32();
-                let span_id = self.read_u32();
+                let raw_idx = self.reader.read_u32();
+                let span_id = self.reader.read_u32();
                 ("Assert", format!("text_id={} span={}", raw_idx, span_id))
             }
             Op::LookupWith => {
-                let idx = self.read_u32();
+                let idx = self.reader.read_u32();
                 let name = self.ctx.resolve_string(idx);
-                let n = self.read_u8();
+                let n = self.reader.read_u8();
                 for _ in 0..n {
-                    self.read_operand_data();
+                    let _ = self.reader.read_operand_data();
                 }
                 ("LookupWith", format!("sym={:?} n={}", name, n))
             }
 
             Op::LoadBuiltins => ("LoadBuiltins", String::new()),
             Op::LoadBuiltin => {
-                let id = self.read_u8();
+                let id = self.reader.read_u8();
                 ("LoadBuiltin", format!("id={}", id))
             }
             Op::LoadReplBinding => {
-                let idx = self.read_u32();
+                let idx = self.reader.read_u32();
                 let name = self.ctx.resolve_string(idx);
                 ("LoadReplBinding", format!("{:?}", name))
             }
             Op::LoadScopedBinding => {
-                let slot = self.read_u32();
-                let idx = self.read_u32();
+                let slot = self.reader.read_u32();
+                let idx = self.reader.read_u32();
                 let name = self.ctx.resolve_string(idx);
                 ("LoadScopedBinding", format!("slot={} {:?}", slot, name))
             }

fix-bytecode/src/lib.rs

@@ -0,0 +1,614 @@
+#![allow(
+    dead_code,
+    reason = "crate is under active development; some opcodes and helpers are not yet wired up"
+)]
+
+use fix_lang::{BuiltinId, StringId};
+use num_enum::TryFromPrimitive;
+use string_interner::Symbol as _;
+
+pub mod disassembler;
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub struct InstructionPtr(pub usize);
+
+#[repr(u8)]
+#[derive(Debug, Clone, Copy)]
+pub enum Op {
+    PushSmi,
+    PushBigInt,
+    PushFloat,
+    PushString,
+    PushNull,
+    PushTrue,
+    PushFalse,
+
+    LoadLocal,
+    LoadOuter,
+    StoreLocal,
+    AllocLocals,
+
+    MakeThunk,
+    MakeClosure,
+    MakePatternClosure,
+
+    Call,
+    DispatchCont,
+
+    MakeAttrs,
+    MakeEmptyAttrs,
+    SelectStatic,
+    SelectDynamic,
+    HasAttrPathStatic,
+    HasAttrPathDynamic,
+    HasAttrStatic,
+    HasAttrDynamic,
+    HasAttrResolve,
+    JumpIfSelectSucceeded,
+    JumpIfSelectFailed,
+
+    MakeList,
+    MakeEmptyList,
+
+    OpAdd,
+    OpSub,
+    OpMul,
+    OpDiv,
+    OpEq,
+    OpNeq,
+    OpLt,
+    OpGt,
+    OpLeq,
+    OpGeq,
+    OpConcat,
+    OpUpdate,
+
+    OpNeg,
+    OpNot,
+
+    JumpIfFalse,
+    JumpIfTrue,
+    Jump,
+
+    CoerceToString,
+
+    ConcatStrings,
+    ResolvePath,
+
+    Assert,
+
+    LookupWith,
+
+    LoadBuiltins,
+    LoadBuiltin,
+
+    LoadReplBinding,
+    LoadScopedBinding,
+
+    Return,
+
+    Illegal,
+}
+
+impl TryFrom<u8> for Op {
+    type Error = u8;
+
+    #[inline(always)]
+    fn try_from(value: u8) -> Result<Self, Self::Error> {
+        if (0..Self::Illegal as u8).contains(&value) {
+            // SAFETY: `value` is in `0..Illegal`, which are exactly the valid
+            // discriminants of this `#[repr(u8)]` enum, so the transmute is sound.
+            Ok(unsafe { std::mem::transmute::<u8, Self>(value) })
+        } else {
+            Err(value)
+        }
+    }
+}
+
+#[repr(u8)]
+#[derive(Debug, Clone, Copy, TryFromPrimitive)]
+pub enum OperandType {
+    Const,
+    BigInt,
+    Local,
+    BuiltinConst,
+    Builtins,
+    ReplBinding,
+    ScopedImportBinding,
+}
+
+pub enum Const {
+    Smi(i32),
+    Float(f64),
+    Bool(bool),
+    String(StringId),
+    Path(StringId),
+    PrimOp(BuiltinId),
+    Null,
+}
+
+#[repr(u8)]
+#[derive(Debug, Clone, Copy, TryFromPrimitive)]
+pub enum AttrKeyType {
+    Static,
+    Dynamic,
+}
+
+pub enum OperandData {
+    Const(u32),
+    BigInt(i64),
+    Local { layer: u8, idx: u32 },
+    BuiltinConst(StringId),
+    Builtins,
+    ReplBinding(StringId),
+    ScopedImportBinding { slot_id: u32, name: StringId },
+}
+
+#[repr(u8)]
+#[derive(Debug, Clone, Copy, Hash, PartialEq, Eq)]
+pub enum Continuation {
+    // primops
+    PAbort,
+    PAdd,
+    PAddErrorContext,
+
+    PAll0,
+    PAll1,
+    PAll2,
+    PAll3,
+
+    PAny0,
+    PAny1,
+    PAny2,
+    PAny3,
+
+    PAppendContext,
+    PAppendContextLoop,
+    PAppendContextEntryForced,
+    PAppendContextOutputsForced,
+    PAppendContextOutputElementLoop,
+    PAppendContextOutputElementForced,
+
+    PAttrNames,
+    PAttrValues,
+    PBaseNameOf,
+    PBitAnd,
+    PBitOr,
+    PBitXor,
+    PBreak,
+    PCatAttrs,
+    PCeil,
+    PCompareVersions,
+    PConcatLists,
+    PConcatMap,
+    PConcatStringsSep,
+    PConvertHash,
+
+    PDeepSeq0,
+    PDeepSeq1,
+    PDeepSeq2,
+    PDeepSeq3,
+    PDeepSeq4,
+    PDeepSeq5,
+
+    PDerivation,
+    PDerivationStrict,
+    PDirOf,
+    PDiv,
+    PElem,
+    PElemAt,
+    PFetchGit,
+    PFetchMercurial,
+    PFetchTarball,
+    PFetchTree,
+    PFetchUrl,
+
+    PFilter0,
+    PFilter1,
+    PFilter2,
+    PFilter3,
+    PFilter4,
+
+    PFilterSource,
+    PFindFile,
+    PFloor,
+    PFoldlStrict0,
+    PFoldlStrict1,
+    PFoldlStrict2,
+    PFoldlStrict3,
+    PFoldlStrict4,
+    PFoldlStrict5,
+    PFromJSON,
+    PFromTOML,
+    PFunctionArgs,
+    PGenList,
+    PGenericClosure,
+    PGetAttr,
+    PGetContext,
+    PGetEnv,
+    PGroupBy,
+    PHasAttr,
+    PHasContext,
+    PHashFile,
+    PHashString,
+    PHead,
+
+    PImport,
+    PImportFinalize,
+    PScopedImport,
+    PScopedImportFinalize,
+
+    PIntersectAttrs,
+    PIsAttrs,
+    PIsBool,
+    PIsFloat,
+    PIsFunction,
+    PIsInt,
+    PIsList,
+    PIsNull,
+    PIsPath,
+    PIsString,
+    PLength,
+    PLessThan,
+    PListToAttrs,
+    PMap,
+    PMapAttrs,
+    PMatch,
+    PMul,
+    PParseDrvName,
+    PPartition,
+    PPath,
+    PPathExists,
+    PPlaceholder,
+    PReadDir,
+    PReadFile,
+    PReadFileType,
+    PRemoveAttrs,
+    PReplaceStrings,
+    PSeq0,
+    PSeq1,
+    PSort,
+    PSplit,
+    PSplitVersion,
+    PStorePath,
+    PStringLength,
+    PSub,
+    PSubstring,
+    PTail,
+    PThrow,
+    PToFile,
+    PToJSON,
+    PToPath,
+    PToString,
+    PToXML,
+    PTrace,
+    PTryEval,
+    PTypeOf,
+    PUnsafeDiscardStringContext,
+    PUnsafeGetAttrPos,
+    PWarn,
+    PZipAttrsWith,
+    PUnsafeDiscardOutputDependency,
+
+    ForceResultShallow,
+    ForceResultShallowPush,
+    ForceResultShallowLoop,
+    ForceResultDeepFinish,
+
+    EqStep,
+    EqForce,
+
+    CallPattern,
+    CallFunctor1,
+    CallFunctor2,
+
+    Illegal,
+}
+
+impl TryFrom<u8> for Continuation {
+    type Error = u8;
+
+    #[inline(always)]
+    fn try_from(value: u8) -> Result<Self, Self::Error> {
+        if (0..Self::Illegal as u8).contains(&value) {
+            // SAFETY: `value` is in `0..Illegal`, which are exactly the valid
+            // discriminants of this `#[repr(u8)]` enum, so the transmute is sound.
+            Ok(unsafe { std::mem::transmute::<u8, Self>(value) })
+        } else {
+            Err(value)
+        }
+    }
+}
+
+impl Continuation {
+    pub const fn entry_for_builtin(id: BuiltinId) -> Self {
+        use BuiltinId::*;
+        match id {
+            Abort => Self::PAbort,
+            Add => Self::PAdd,
+            AddErrorContext => Self::PAddErrorContext,
+            All => Self::PAll0,
+            Any => Self::PAny0,
+            AppendContext => Self::PAppendContext,
+            AttrNames => Self::PAttrNames,
+            AttrValues => Self::PAttrValues,
+            BaseNameOf => Self::PBaseNameOf,
+            BitAnd => Self::PBitAnd,
+            BitOr => Self::PBitOr,
+            BitXor => Self::PBitXor,
+            Break => Self::PBreak,
+            CatAttrs => Self::PCatAttrs,
+            Ceil => Self::PCeil,
+            CompareVersions => Self::PCompareVersions,
+            ConcatLists => Self::PConcatLists,
+            ConcatMap => Self::PConcatMap,
+            ConcatStringsSep => Self::PConcatStringsSep,
+            ConvertHash => Self::PConvertHash,
+            DeepSeq => Self::PDeepSeq0,
+            Derivation => Self::PDerivation,
+            DerivationStrict => Self::PDerivationStrict,
+            DirOf => Self::PDirOf,
+            Div => Self::PDiv,
+            Elem => Self::PElem,
+            ElemAt => Self::PElemAt,
+            FetchGit => Self::PFetchGit,
+            FetchMercurial => Self::PFetchMercurial,
+            FetchTarball => Self::PFetchTarball,
+            FetchTree => Self::PFetchTree,
+            FetchUrl => Self::PFetchUrl,
+            Filter => Self::PFilter0,
+            FilterSource => Self::PFilterSource,
+            FindFile => Self::PFindFile,
+            Floor => Self::PFloor,
+            FoldlStrict => Self::PFoldlStrict0,
+            FromJSON => Self::PFromJSON,
+            FromTOML => Self::PFromTOML,
+            FunctionArgs => Self::PFunctionArgs,
+            GenList => Self::PGenList,
+            GenericClosure => Self::PGenericClosure,
+            GetAttr => Self::PGetAttr,
+            GetContext => Self::PGetContext,
+            GetEnv => Self::PGetEnv,
+            GroupBy => Self::PGroupBy,
+            HasAttr => Self::PHasAttr,
+            HasContext => Self::PHasContext,
+            HashFile => Self::PHashFile,
+            HashString => Self::PHashString,
+            Head => Self::PHead,
+            Import => Self::PImport,
+            IntersectAttrs => Self::PIntersectAttrs,
+            IsAttrs => Self::PIsAttrs,
+            IsBool => Self::PIsBool,
+            IsFloat => Self::PIsFloat,
+            IsFunction => Self::PIsFunction,
+            IsInt => Self::PIsInt,
+            IsList => Self::PIsList,
+            IsNull => Self::PIsNull,
+            IsPath => Self::PIsPath,
+            IsString => Self::PIsString,
+            Length => Self::PLength,
+            LessThan => Self::PLessThan,
+            ListToAttrs => Self::PListToAttrs,
+            Map => Self::PMap,
+            MapAttrs => Self::PMapAttrs,
+            Match => Self::PMatch,
+            Mul => Self::PMul,
+            ParseDrvName => Self::PParseDrvName,
+            Partition => Self::PPartition,
+            Path => Self::PPath,
+            PathExists => Self::PPathExists,
+            Placeholder => Self::PPlaceholder,
+            ReadDir => Self::PReadDir,
+            ReadFile => Self::PReadFile,
+            ReadFileType => Self::PReadFileType,
+            RemoveAttrs => Self::PRemoveAttrs,
+            ReplaceStrings => Self::PReplaceStrings,
+            ScopedImport => Self::PScopedImport,
+            Seq => Self::PSeq0,
+            Sort => Self::PSort,
+            Split => Self::PSplit,
+            SplitVersion => Self::PSplitVersion,
+            StorePath => Self::PStorePath,
+            StringLength => Self::PStringLength,
+            Sub => Self::PSub,
+            Substring => Self::PSubstring,
+            Tail => Self::PTail,
+            Throw => Self::PThrow,
+            ToFile => Self::PToFile,
+            ToJSON => Self::PToJSON,
+            ToPath => Self::PToPath,
+            ToString => Self::PToString,
+            ToXML => Self::PToXML,
+            Trace => Self::PTrace,
+            TryEval => Self::PTryEval,
+            TypeOf => Self::PTypeOf,
+            UnsafeDiscardStringContext => Self::PUnsafeDiscardStringContext,
+            UnsafeDiscardOutputDependency => Self::PUnsafeDiscardOutputDependency,
+            UnsafeGetAttrPos => Self::PUnsafeGetAttrPos,
+            Warn => Self::PWarn,
+            ZipAttrsWith => Self::PZipAttrsWith,
+        }
+    }
+
+    pub const fn ip(self) -> u32 {
+        self as u32 * 2
+    }
+}
+
+pub struct BytecodeReader<'a> {
+    bytecode: &'a [u8],
+    pc: usize,
+    inst_start_pc: usize,
+}
+
+impl std::ops::Deref for BytecodeReader<'_> {
+    type Target = [u8];
+    fn deref(&self) -> &Self::Target {
+        self.bytecode
+    }
+}
+
+pub trait FromBytecode {
+    #[must_use]
+    fn read(reader: &mut BytecodeReader<'_>) -> Self;
+}
+
+impl<const N: usize> FromBytecode for [u8; N] {
+    #[inline(always)]
+    #[expect(
+        clippy::indexing_slicing,
+        reason = "reads well-formed bytecode; an out-of-range PC indicates a codegen bug and should panic loudly"
+    )]
+    fn read(reader: &mut BytecodeReader<'_>) -> Self {
+        let ret = reader.bytecode[reader.pc..reader.pc + N]
+            .try_into()
+            .expect("read_array failed");
+        reader.pc += N;
+        ret
+    }
+}
+
+impl FromBytecode for u8 {
+    #[inline(always)]
+    fn read(reader: &mut BytecodeReader<'_>) -> Self {
+        let [byte] = reader.read();
+        byte
+    }
+}
+
+macro_rules! numbers_impl {
+    ( $($ty:ty),* ) => {
+        $(
+        impl FromBytecode for $ty {
+            #[inline(always)]
+            fn read(reader: &mut BytecodeReader<'_>) -> Self {
+                <$ty>::from_le_bytes(FromBytecode::read(reader))
+            }
+        }
+        )*
+    };
+}
+
+numbers_impl!(u16, u32, i32, i64, f64);
+
+impl FromBytecode for Op {
+    #[inline(always)]
+    #[expect(
+        clippy::panic,
+        reason = "reads well-formed bytecode; an unknown opcode indicates a codegen bug and should panic loudly"
+    )]
+    fn read(reader: &mut BytecodeReader<'_>) -> Self {
+        reader.inst_start_pc = reader.pc;
+        let byte: u8 = reader.read();
+        byte.try_into().unwrap_or_else(|byte| {
+            std::hint::cold_path();
+            panic!("unknown opcode: {byte:#04x}")
+        })
+    }
+}
+
+impl FromBytecode for StringId {
+    #[inline(always)]
+    fn read(reader: &mut BytecodeReader<'_>) -> Self {
+        let raw: u32 = reader.read();
+        StringId(
+            string_interner::symbol::SymbolU32::try_from_usize(raw as usize)
+                .expect("raw is a valid interner symbol index"),
+        )
+    }
+}
+
+impl FromBytecode for OperandData {
+    #[inline(always)]
+    #[expect(
+        clippy::panic,
+        reason = "an unknown operand tag in well-formed bytecode indicates a codegen bug and should panic loudly"
+    )]
+    fn read(reader: &mut BytecodeReader<'_>) -> Self {
+        let tag = reader.read();
+        let ty = OperandType::try_from_primitive(tag).unwrap_or_else(|err| {
+            std::hint::cold_path();
+            panic!("unknown operand tag: {:#04x}", err.number)
+        });
+        match ty {
+            OperandType::Const => OperandData::Const(reader.read()),
+            OperandType::BigInt => OperandData::BigInt(reader.read()),
+            OperandType::Local => {
+                let layer = reader.read();
+                let idx = reader.read();
+                OperandData::Local { layer, idx }
+            }
+            OperandType::BuiltinConst => OperandData::BuiltinConst(reader.read()),
+            OperandType::Builtins => OperandData::Builtins,
+            OperandType::ReplBinding => OperandData::ReplBinding(reader.read()),
+            OperandType::ScopedImportBinding => {
+                let slot_id = reader.read();
+                let name = reader.read();
+                OperandData::ScopedImportBinding { slot_id, name }
+            }
+        }
+    }
+}
+
+macro_rules! read_aliases {
+    { $($alias:ident -> $ty:ty),*$(,)? } => {
+        $(
+        #[inline(always)]
+        #[must_use]
+        pub fn $alias(&mut self) -> $ty {
+            <$ty>::read(self)
+        }
+        )*
+    };
+}
+
+impl<'a> BytecodeReader<'a> {
+    #[must_use]
+    pub fn new(bytecode: &'a [u8], pc: usize) -> Self {
+        Self {
+            bytecode,
+            pc,
+            inst_start_pc: pc,
+        }
+    }
+
+    #[inline(always)]
+    #[must_use]
+    pub fn from_after_op(bytecode: &'a [u8], inst_start_pc: usize) -> Self {
+        Self {
+            bytecode,
+            pc: inst_start_pc + 1,
+            inst_start_pc,
+        }
+    }
+
+    #[inline(always)]
+    #[must_use]
+    pub fn read<T: FromBytecode>(&mut self) -> T {
+        T::read(self)
+    }
+
+    read_aliases! {
+        read_op -> Op,
+        read_u8 -> u8,
+        read_u16 -> u16,
+        read_u32 -> u32,
+        read_i32 -> i32,
+        read_i64 -> i64,
+        read_f64 -> f64,
+        read_string_id -> StringId,
+        read_operand_data -> OperandData,
+    }
+
+    pub fn pc(&self) -> usize {
+        self.pc
+    }
+
+    pub fn set_pc(&mut self, pc: usize) {
+        self.pc = pc;
+    }
+
+    pub fn inst_start_pc(&self) -> usize {
+        self.inst_start_pc
+    }
+}

fix-codegen/Cargo.toml

@@ -1,15 +0,0 @@
-[package]
-name = "fix-codegen"
-version = "0.1.0"
-edition = "2024"
-
-[dependencies]
-hashbrown = { workspace = true }
-num_enum = { workspace = true }
-rnix = { workspace = true }
-string-interner = { workspace = true }
-colored = "3.1.1"
-
-fix-builtins = { path = "../fix-builtins" }
-fix-common = { path = "../fix-common" }
-fix-ir = { path = "../fix-ir" }

fix-compiler/Cargo.toml

@@ -1,17 +1,22 @@
 [package]
-name = "fix-ir"
+name = "fix-compiler"
 version = "0.1.0"
 edition = "2024"
 
 [dependencies]
 bumpalo = { workspace = true }
+colored = "3.1.1"
 ghost-cell = { workspace = true }
+hashbrown = { workspace = true }
 rnix = { workspace = true }
 rowan = { workspace = true }
 string-interner = { workspace = true }
-hashbrown = { workspace = true }
-num_enum = { workspace = true }
 
-fix-builtins = { path = "../fix-builtins" }
-fix-common = { path = "../fix-common" }
+fix-bytecode = { path = "../fix-bytecode" }
 fix-error = { path = "../fix-error" }
+fix-lang = { path = "../fix-lang" }
+fix-runtime = { path = "../fix-runtime" }
+tracing = "0.1"
+
+[lints]
+workspace = true

fix-compiler/src/context.rs

@@ -0,0 +1,570 @@
+use bumpalo::Bump;
+use fix_bytecode::{Const, Continuation, InstructionPtr, Op};
+use fix_error::{Error, Result, Source};
+use fix_lang::{StringId, Symbol};
+use fix_runtime::{StaticValue, VmCode, VmRuntimeCtx};
+use ghost_cell::{GhostCell, GhostToken};
+use hashbrown::{HashMap, HashSet};
+use string_interner::DefaultStringInterner;
+
+use crate::BytecodeContext;
+use crate::ir::downgrade::{Downgrade as _, DowngradeContext};
+use crate::ir::{
+    GhostMaybeThunkRef, GhostRoIrRef, GhostRoMaybeThunkRef, GhostRoRef, Ir, MaybeThunk, RawIrRef,
+    ThunkId,
+};
+
+pub struct CodeState {
+    pub bytecode: Vec<u8>,
+    pub sources: Vec<Source>,
+    pub spans: Vec<(usize, rnix::TextRange)>,
+    pub thunk_count: usize,
+    pub global_env: HashMap<StringId, MaybeThunk>,
+}
+
+impl CodeState {
+    pub fn new(strings: &mut DefaultStringInterner) -> Self {
+        let global_env = crate::ir::new_global_env(strings);
+        let mut bytecode = Vec::with_capacity(Continuation::Illegal as usize * 2);
+        for phase in 0..=Continuation::Illegal as u8 {
+            bytecode.push(Op::DispatchCont as u8);
+            bytecode.push(phase);
+        }
+        Self {
+            sources: Vec::new(),
+            spans: Vec::new(),
+            thunk_count: 0,
+            bytecode,
+            global_env,
+        }
+    }
+
+    pub fn compile_bytecode<'ctx>(
+        &'ctx mut self,
+        source: Source,
+        extra_scope: Option<ExtraScope<'ctx>>,
+        runtime: &'ctx mut impl VmRuntimeCtx,
+    ) -> Result<InstructionPtr> {
+        let mut compiler = CompilerCtx {
+            code: self,
+            runtime,
+        };
+        compiler.compile_bytecode(source, extra_scope)
+    }
+}
+
+impl VmCode for CodeState {
+    fn bytecode(&self) -> &[u8] {
+        &self.bytecode
+    }
+
+    fn compile_with_scope(
+        &mut self,
+        source: Source,
+        extra_scope: Option<fix_runtime::ExtraScope>,
+        runtime: &mut impl VmRuntimeCtx,
+    ) -> Result<InstructionPtr> {
+        let extra = extra_scope.map(|s| match s {
+            fix_runtime::ExtraScope::ScopedImport { keys, slot_id } => {
+                ExtraScope::ScopedImport { keys, slot_id }
+            }
+        });
+        CodeState::compile_bytecode(self, source, extra, runtime)
+    }
+}
+
+struct CompilerCtx<'a, R: VmRuntimeCtx> {
+    code: &'a mut CodeState,
+    runtime: &'a mut R,
+}
+
+impl<'a, R: VmRuntimeCtx> CompilerCtx<'a, R> {
+    fn compile_bytecode(
+        &mut self,
+        source: Source,
+        extra_scope: Option<ExtraScope>,
+    ) -> Result<InstructionPtr> {
+        let root = self.downgrade(source, extra_scope)?;
+        let ip = crate::compile_bytecode(root.as_ref(), self);
+        Ok(ip)
+    }
+
+    fn downgrade(&mut self, source: Source, extra_scope: Option<ExtraScope>) -> Result<OwnedIr> {
+        tracing::debug!("Parsing Nix expression");
+
+        self.code.sources.push(source.clone());
+
+        let root = rnix::Root::parse(&source.src);
+        handle_parse_error(root.errors(), source.clone()).map_or(Ok(()), Err)?;
+
+        tracing::debug!("Downgrading Nix expression");
+        let expr = root
+            .tree()
+            .expr()
+            .ok_or_else(|| Error::parse_error("unexpected EOF".into()))?;
+        let bump = Bump::new();
+        GhostToken::new(|token| {
+            let downgrade_ctx = DowngradeCtx::new(
+                &bump,
+                token,
+                self.runtime,
+                &self.code.global_env,
+                extra_scope.map(Into::into),
+                &mut self.code.thunk_count,
+                source,
+            );
+            let ir = downgrade_ctx.downgrade_toplevel(expr)?;
+            // SAFETY: `ir` borrows from `bump`, which is moved into the returned
+            // `OwnedIr` alongside the reference. The `'static` lifetime is a
+            // storage token that is re-narrowed to the `OwnedIr`'s own borrow in
+            // `as_ref`, so no reference ever outlives the arena backing it.
+            let ir = unsafe { std::mem::transmute::<RawIrRef<'_>, RawIrRef<'static>>(ir) };
+            // SAFETY: `ir` borrows from `bump`
+            Ok(unsafe { OwnedIr::new(bump, ir) })
+        })
+    }
+}
+
+impl<'a, R: VmRuntimeCtx> BytecodeContext for CompilerCtx<'a, R> {
+    fn intern_string(&mut self, s: &str) -> StringId {
+        self.runtime.intern_string(s)
+    }
+
+    fn register_span(&mut self, range: rnix::TextRange) -> u32 {
+        let id = self.code.spans.len();
+        let source_id = self
+            .code
+            .sources
+            .len()
+            .checked_sub(1)
+            .expect("current_source not set");
+        self.code.spans.push((source_id, range));
+        id as u32
+    }
+
+    fn get_code(&self) -> &[u8] {
+        &self.code.bytecode
+    }
+
+    fn get_code_mut(&mut self) -> &mut Vec<u8> {
+        &mut self.code.bytecode
+    }
+
+    fn add_constant(&mut self, val: Const) -> u32 {
+        use Const::*;
+        let val = match val {
+            Smi(x) => StaticValue::new(x),
+            Float(x) => StaticValue::new(x),
+            Bool(x) => StaticValue::new(x),
+            String(x) => StaticValue::new(x),
+            Path(x) => StaticValue::new(fix_runtime::Path(x)),
+            PrimOp(id) => StaticValue::new(fix_runtime::PrimOp::from(id)),
+            Null => StaticValue::default(),
+        };
+        self.runtime.add_const(val)
+    }
+
+    fn current_source_dir(&mut self) -> StringId {
+        let dir = self
+            .code
+            .sources
+            .last()
+            .expect("current_source not set")
+            .get_dir()
+            .to_string_lossy()
+            .into_owned();
+        self.runtime.intern_string(dir)
+    }
+}
+
+fn parse_error_span(error: &rnix::ParseError) -> Option<rnix::TextRange> {
+    use rnix::ParseError::*;
+    match error {
+        Unexpected(range)
+        | UnexpectedExtra(range)
+        | UnexpectedWanted(_, range, _)
+        | UnexpectedDoubleBind(range)
+        | DuplicatedArgs(range, _) => Some(*range),
+        _ => None,
+    }
+}
+
+fn handle_parse_error<'a>(
+    errors: impl IntoIterator<Item = &'a rnix::ParseError>,
+    source: Source,
+) -> Option<Box<Error>> {
+    for err in errors {
+        if let Some(span) = parse_error_span(err) {
+            return Some(
+                Error::parse_error(err.to_string())
+                    .with_source(source)
+                    .with_span(span),
+            );
+        }
+    }
+    None
+}
+
+struct DowngradeCtx<'ctx, 'id, 'ir, R: VmRuntimeCtx> {
+    bump: &'ir Bump,
+    token: GhostToken<'id>,
+    runtime: &'ctx mut R,
+    source: Source,
+    scopes: Vec<Scope<'ctx, 'id, 'ir>>,
+    with_stack: Vec<GhostRoMaybeThunkRef<'id, 'ir>>,
+    thunk_count: &'ctx mut usize,
+    thunk_scopes: Vec<ThunkScope<'id, 'ir>>,
+}
+
+impl<'ctx, 'id, 'ir, R: VmRuntimeCtx> DowngradeCtx<'ctx, 'id, 'ir, R> {
+    fn new(
+        bump: &'ir Bump,
+        token: GhostToken<'id>,
+        runtime: &'ctx mut R,
+        global: &'ctx HashMap<StringId, MaybeThunk>,
+        extra_scope: Option<Scope<'ctx, 'id, 'ir>>,
+        thunk_count: &'ctx mut usize,
+        source: Source,
+    ) -> Self {
+        Self {
+            bump,
+            token,
+            runtime,
+            source,
+            scopes: std::iter::once(Scope::Global(global))
+                .chain(extra_scope)
+                .collect(),
+            thunk_count,
+            with_stack: Vec::new(),
+            thunk_scopes: vec![ThunkScope::new_in(bump)],
+        }
+    }
+}
+
+impl<'ctx: 'ir, 'id, 'ir, R: VmRuntimeCtx> DowngradeContext<'id, 'ir>
+    for DowngradeCtx<'ctx, 'id, 'ir, R>
+{
+    fn new_expr(&self, expr: Ir<'ir, GhostRoRef<'id, 'ir>>) -> GhostRoIrRef<'id, 'ir> {
+        self.bump.alloc(GhostCell::new(expr).into())
+    }
+
+    fn maybe_thunk(&mut self, ir: GhostRoIrRef<'id, 'ir>) -> GhostRoMaybeThunkRef<'id, 'ir> {
+        use MaybeThunk::*;
+        let expr = (|| {
+            let expr = match *ir.borrow(&self.token) {
+                Ir::Builtin(x) => Builtin(x),
+                Ir::Int(x) => Int(x),
+                Ir::Float(x) => Float(x),
+                Ir::Bool(x) => Bool(x),
+                Ir::Str(x) => Str(x),
+                Ir::Arg { layer } => Arg { layer },
+                Ir::Builtins => Builtins,
+                Ir::Null => Null,
+                Ir::MaybeThunk(thunk) => return Some(thunk),
+                _ => return None,
+            };
+            Some(self.bump.alloc(GhostCell::new(expr).into()))
+        })();
+        if let Some(thunk) = expr {
+            return thunk;
+        }
+        let id = ThunkId(*self.thunk_count);
+        *self.thunk_count = self.thunk_count.checked_add(1).expect("thunk id overflow");
+        self.thunk_scopes
+            .last_mut()
+            .expect("no active cache scope")
+            .add_binding(id, ir);
+        self.bump.alloc(GhostCell::new(Thunk(id)).into())
+    }
+
+    fn intern_string(&mut self, sym: impl AsRef<str>) -> StringId {
+        self.runtime.intern_string(sym)
+    }
+
+    fn resolve_sym(&self, id: StringId) -> Symbol<'_> {
+        self.runtime.resolve_string(id).into()
+    }
+
+    #[expect(
+        clippy::unwrap_in_result,
+        reason = "exceeding u8::MAX thunk scope layers is a compiler invariant violation, not a user-facing error"
+    )]
+    fn lookup(
+        &mut self,
+        sym: StringId,
+        span: rnix::TextRange,
+    ) -> Result<GhostRoMaybeThunkRef<'id, 'ir>> {
+        for scope in self.scopes.iter().rev() {
+            match scope {
+                &Scope::Global(global_scope) => {
+                    if let Some(expr) = global_scope.get(&sym) {
+                        return Ok(expr.into());
+                    }
+                }
+                &Scope::Repl(repl_bindings) => {
+                    if repl_bindings.contains(&sym) {
+                        return Ok(self
+                            .bump
+                            .alloc(GhostCell::new(MaybeThunk::ReplBinding(sym)).into()));
+                    }
+                }
+                &Scope::ScopedImport { ref keys, slot_id } => {
+                    if keys.contains(&sym) {
+                        return Ok(self.bump.alloc(
+                            GhostCell::new(MaybeThunk::ScopedImportBinding { sym, slot_id }).into(),
+                        ));
+                    }
+                }
+                Scope::Let(let_scope) => {
+                    if let Some(&expr) = let_scope.get(&sym) {
+                        return Ok(expr.into());
+                    }
+                }
+                &Scope::Param {
+                    sym: param_sym,
+                    abs_layer,
+                } => {
+                    if param_sym == sym {
+                        let layers: u8 =
+                            self.thunk_scopes.len().try_into().expect("scope too deep!");
+                        let layer = layers - abs_layer;
+                        return Ok(self
+                            .bump
+                            .alloc(GhostCell::new(MaybeThunk::Arg { layer }).into()));
+                    }
+                }
+            }
+        }
+
+        if !self.with_stack.is_empty() {
+            let id = ThunkId(*self.thunk_count);
+            *self.thunk_count = self.thunk_count.checked_add(1).expect("thunk id overflow");
+            let mut namespaces =
+                bumpalo::collections::Vec::with_capacity_in(self.with_stack.len(), self.bump);
+            namespaces.extend(self.with_stack.iter().rev().copied());
+            let body = self
+                .bump
+                .alloc(GhostCell::new(Ir::WithLookup { sym, namespaces }).into());
+            self.thunk_scopes
+                .last_mut()
+                .expect("no active thunk scope")
+                .add_binding(id, body);
+            Ok(self
+                .bump
+                .alloc(GhostCell::new(MaybeThunk::Thunk(id)).into()))
+        } else {
+            Err(Error::downgrade_error(
+                format!("'{}' not found", self.resolve_sym(sym)),
+                self.get_current_source(),
+                span,
+            ))
+        }
+    }
+
+    fn get_current_source(&self) -> Source {
+        self.source.clone()
+    }
+
+    #[expect(
+        clippy::panic_in_result_fn,
+        reason = "assert_eq guards an internal invariant (bindings and values have equal length); a mismatch is a compiler bug, not a user error"
+    )]
+    fn with_let_scope<F, Ret>(&mut self, keys: &[StringId], f: F) -> Result<Ret>
+    where
+        F: FnOnce(
+            &mut Self,
+        ) -> Result<(
+            bumpalo::collections::Vec<'ir, GhostRoMaybeThunkRef<'id, 'ir>>,
+            Ret,
+        )>,
+    {
+        let base = *self.thunk_count;
+        *self.thunk_count = self
+            .thunk_count
+            .checked_add(keys.len())
+            .expect("thunk id overflow");
+        let handles = (base..base + keys.len())
+            .map(|id| {
+                &*self
+                    .bump
+                    .alloc(GhostCell::new(MaybeThunk::Thunk(ThunkId(id))))
+            })
+            .collect::<Vec<_>>();
+        let scope = keys.iter().copied().zip(handles.iter().copied()).collect();
+        self.scopes.push(Scope::Let(scope));
+        let (vals, ret) = { f(self)? };
+        self.scopes.pop();
+        assert_eq!(keys.len(), vals.len());
+        let scope = self.thunk_scopes.last_mut().expect("no active thunk scope");
+        for (i, (val, handle)) in vals.into_iter().zip(handles).enumerate() {
+            let thunk = *val.borrow(&self.token);
+            *handle.borrow_mut(&mut self.token) = thunk;
+            let id = ThunkId(base + i);
+            let ir_ref = self
+                .bump
+                .alloc(GhostCell::new(Ir::MaybeThunk(handle.into())).into());
+            scope.add_binding(id, ir_ref);
+        }
+        Ok(ret)
+    }
+
+    fn with_param_scope<F, Ret>(&mut self, sym: StringId, f: F) -> Ret
+    where
+        F: FnOnce(&mut Self) -> Ret,
+    {
+        self.scopes.push(Scope::Param {
+            sym,
+            abs_layer: self.thunk_scopes.len().try_into().expect("scope too deep!"),
+        });
+        let mut guard = ScopeGuard { ctx: self };
+        f(guard.as_ctx())
+    }
+
+    fn with_with_scope<F, Ret>(&mut self, namespace: GhostRoMaybeThunkRef<'id, 'ir>, f: F) -> Ret
+    where
+        F: FnOnce(&mut Self) -> Ret,
+    {
+        self.with_stack.push(namespace);
+        let ret = f(self);
+        self.with_stack.pop();
+        ret
+    }
+
+    #[expect(
+        clippy::panic,
+        reason = "exceeding u8::MAX thunk scope layers is a compiler invariant violation, not a user-facing error"
+    )]
+    fn with_thunk_scope<F, Ret>(
+        &mut self,
+        f: F,
+    ) -> (
+        Ret,
+        bumpalo::collections::Vec<'ir, (ThunkId, GhostRoIrRef<'id, 'ir>)>,
+    )
+    where
+        F: FnOnce(&mut Self) -> Ret,
+    {
+        if self.thunk_scopes.len() == u8::MAX as usize {
+            panic!("scope too deep!");
+        }
+        self.thunk_scopes.push(ThunkScope::new_in(self.bump));
+        let ret = f(self);
+        (
+            ret,
+            self.thunk_scopes
+                .pop()
+                .expect("no thunk scope left???")
+                .bindings,
+        )
+    }
+
+    fn bump(&self) -> &'ir bumpalo::Bump {
+        self.bump
+    }
+}
+
+impl<'id, 'ir, 'ctx: 'ir, R: VmRuntimeCtx> DowngradeCtx<'ctx, 'id, 'ir, R> {
+    fn downgrade_toplevel(mut self, root: rnix::ast::Expr) -> Result<RawIrRef<'ir>> {
+        let body = root.downgrade(&mut self)?;
+        let thunks = self
+            .thunk_scopes
+            .pop()
+            .expect("no thunk scope left???")
+            .bindings;
+        Ok(Ir::freeze(
+            self.new_expr(Ir::TopLevel { body, thunks }),
+            self.token,
+        ))
+    }
+}
+
+struct ThunkScope<'id, 'ir> {
+    bindings: bumpalo::collections::Vec<'ir, (ThunkId, GhostRoIrRef<'id, 'ir>)>,
+}
+
+impl<'id, 'ir> ThunkScope<'id, 'ir> {
+    fn new_in(bump: &'ir Bump) -> Self {
+        Self {
+            bindings: bumpalo::collections::Vec::new_in(bump),
+        }
+    }
+
+    fn add_binding(&mut self, id: ThunkId, ir: GhostRoIrRef<'id, 'ir>) {
+        self.bindings.push((id, ir));
+    }
+}
+
+enum Scope<'ctx, 'id, 'ir> {
+    Global(&'ctx HashMap<StringId, MaybeThunk>),
+    Repl(&'ctx HashSet<StringId>),
+    ScopedImport {
+        keys: HashSet<StringId>,
+        slot_id: u32,
+    },
+    Let(HashMap<StringId, GhostMaybeThunkRef<'id, 'ir>>),
+    Param {
+        sym: StringId,
+        abs_layer: u8,
+    },
+}
+
+pub enum ExtraScope<'ctx> {
+    Repl(&'ctx HashSet<StringId>),
+    ScopedImport {
+        keys: HashSet<StringId>,
+        slot_id: u32,
+    },
+}
+
+impl<'ctx> From<ExtraScope<'ctx>> for Scope<'ctx, '_, '_> {
+    fn from(value: ExtraScope<'ctx>) -> Self {
+        use ExtraScope::*;
+        match value {
+            ScopedImport { keys, slot_id } => Scope::ScopedImport { keys, slot_id },
+            Repl(scope) => Scope::Repl(scope),
+        }
+    }
+}
+
+struct ScopeGuard<'a, 'ctx, 'id, 'ir, R: VmRuntimeCtx> {
+    ctx: &'a mut DowngradeCtx<'ctx, 'id, 'ir, R>,
+}
+
+impl<'a, 'ctx, 'id, 'ir, R: VmRuntimeCtx> Drop for ScopeGuard<'a, 'ctx, 'id, 'ir, R> {
+    fn drop(&mut self) {
+        self.ctx.scopes.pop();
+    }
+}
+
+impl<'a, 'ctx, 'id, 'ir, R: VmRuntimeCtx> ScopeGuard<'a, 'ctx, 'id, 'ir, R> {
+    fn as_ctx(&mut self) -> &mut DowngradeCtx<'ctx, 'id, 'ir, R> {
+        self.ctx
+    }
+}
+
+mod sealed {
+    use super::*;
+
+    pub struct OwnedIr {
+        _bump: Bump,
+        ir: RawIrRef<'static>,
+    }
+
+    impl OwnedIr {
+        /// # Safety
+        /// `ir` must borrows from `bump`
+        pub unsafe fn new(bump: Bump, ir: RawIrRef<'static>) -> Self {
+            Self { _bump: bump, ir }
+        }
+
+        pub fn as_ref<'ir>(&'ir self) -> RawIrRef<'ir> {
+            // SAFETY: `self.ir`'s `'static` lifetime is a storage token; the IR is
+            // backed by `self._bump`, which lives as long as `self`. Narrowing to
+            // `'ir` (tied to `&self`) hands out a reference that cannot outlive the
+            // arena.
+            unsafe { std::mem::transmute::<RawIrRef<'static>, RawIrRef<'ir>>(self.ir) }
+        }
+    }
+}
+
+pub use sealed::OwnedIr;

fix-compiler/src/ir.rs

@@ -3,10 +3,8 @@ use std::marker::PhantomData;
 
 use bumpalo::Bump;
 use bumpalo::collections::Vec;
-use fix_builtins::{BUILTINS, BuiltinId};
-use fix_common::StringId;
+use fix_lang::{BuiltinId, StringId};
 use ghost_cell::{GhostCell, GhostToken};
-use num_enum::TryFromPrimitive as _;
 use rnix::{TextRange, ast};
 use string_interner::DefaultStringInterner;
 
@@ -92,7 +90,7 @@ pub enum MaybeThunk {
     BuiltinConst(StringId),
     Builtins,
     ReplBinding(StringId),
-    ScopedImportBinding(StringId),
+    ScopedImportBinding { slot_id: u32, sym: StringId },
 }
 
 pub trait Ref<'ir> {
@@ -213,19 +211,17 @@ pub enum Ir<'ir, R: RefExt<'ir> + ?Sized + 'ir> {
     },
     MaybeThunk(R::MaybeThunkRef),
     ReplBinding(StringId),
-    ScopedImportBinding(StringId),
+    ScopedImportBinding {
+        sym: StringId,
+        slot_id: u32,
+    },
 }
 
 #[repr(transparent)]
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord)]
 pub struct ThunkId(pub usize);
 
-#[repr(transparent)]
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord)]
-pub struct SpanId(pub u32);
-
 /// Represents a key in an attribute path.
-#[allow(unused)]
 #[derive(Debug)]
 pub enum Attr<Ref> {
     /// A dynamic attribute key, which is an expression that must evaluate to a string.
@@ -294,9 +290,8 @@ pub fn new_global_env(
     let builtins_sym = StringId(strings.get_or_intern("builtins"));
     global_env.insert(builtins_sym, MaybeThunk::Builtins);
 
-    for (idx, &(name, _)) in BUILTINS.iter().enumerate() {
-        let id = BuiltinId::try_from_primitive(idx as u8).expect("infallible");
-        let name = StringId(strings.get_or_intern(name));
+    for id in BuiltinId::ALL {
+        let name = StringId(strings.get_or_intern(id.info().global_name));
         global_env.insert(name, MaybeThunk::Builtin(id));
     }
 

fix-compiler/src/ir/downgrade.rs

@@ -1,7 +1,6 @@
 use bumpalo::collections::{CollectIn, Vec};
-use fix_builtins::BuiltinId;
-use fix_common::Symbol;
 use fix_error::{Error, Result, Source};
+use fix_lang::{BuiltinId, Symbol};
 use hashbrown::HashSet;
 use hashbrown::hash_map::Entry;
 use rnix::TextRange;
@@ -157,6 +156,10 @@ impl<'id: 'ir, 'ir, Ctx: DowngradeContext<'id, 'ir>> Downgrade<'id, 'ir, Ctx> fo
         let path = {
             let temp = self.content().require(ctx, span)?;
             let text = temp.text();
+            #[expect(
+                clippy::string_slice,
+                reason = "PathSearch text is <...> wrapped in ASCII angle brackets, so byte indices 1 and len-1 are char boundaries"
+            )]
             let id = ctx.intern_string(&text[1..text.len() - 1]);
             let expr = ctx.new_expr(Ir::Str(id));
             ctx.maybe_thunk(expr)
@@ -463,16 +466,14 @@ impl<'id: 'ir, 'ir, Ctx: DowngradeContext<'id, 'ir>> Downgrade<'id, 'ir, Ctx> fo
             body: GhostRoIrRef<'id, 'ir>,
         }
 
-        let (ret, thunks) = ctx.with_thunk_scope(|ctx| {
-            let param;
-            let body;
-
-            match raw_param {
+        let (ret, thunks) = ctx.with_thunk_scope(|ctx| -> Result<Ret> {
+            let (param, body) = match raw_param {
                 ast::Param::IdentParam(id) => {
                     let param_sym = ctx.intern_string(id.to_string());
-                    param = None;
-
-                    body = ctx.with_param_scope(param_sym, |ctx| body_ast.downgrade(ctx))?;
+                    (
+                        None,
+                        ctx.with_param_scope(param_sym, |ctx| body_ast.downgrade(ctx))?,
+                    )
                 }
                 ast::Param::Pattern(pattern) => {
                     let alias = pattern
@@ -494,17 +495,18 @@ impl<'id: 'ir, 'ir, Ctx: DowngradeContext<'id, 'ir>> Downgrade<'id, 'ir, Ctx> fo
                         body_ast.clone().downgrade(ctx)
                     })?;
 
-                    param = Some(Param {
+                    (
+                        Some(Param {
                             required,
                             optional,
                             ellipsis,
-                    });
-
-                    body = inner_body;
-                }
+                        }),
+                        inner_body,
+                    )
                 }
+            };
 
-            Result::Ok(Ret { param, body })
+            Ok(Ret { param, body })
         });
         let Ret { param, body } = ret?;
 
@@ -551,6 +553,10 @@ impl<'id: 'ir, 'ir> PendingAttrSet<'ir> {
         }
     }
 
+    #[expect(
+        clippy::indexing_slicing,
+        reason = "path is non-empty here: path.first() was just unwrapped above, so path[1..] is in bounds"
+    )]
     fn insert(
         &mut self,
         path: &[ast::Attr],
@@ -652,6 +658,10 @@ impl<'id: 'ir, 'ir> PendingAttrSet<'ir> {
     ) -> Result<()> {
         if !path.is_empty() {
             let mut nested = PendingAttrSet::new_in(ctx.bump());
+            #[expect(
+                clippy::indexing_slicing,
+                reason = "path is non-empty in this branch, so path[0] and path[1..] are in bounds"
+            )]
             nested.insert_dynamic(
                 path[0].clone(),
                 path[0].syntax().text_range(),
@@ -666,6 +676,10 @@ impl<'id: 'ir, 'ir> PendingAttrSet<'ir> {
         Ok(())
     }
 
+    #[expect(
+        clippy::unreachable,
+        reason = "value was just reassigned to PendingValue::Set on the line above, so the re-match always hits the Set arm"
+    )]
     fn ensure_pending_set<'a>(
         value: &'a mut PendingValue<'ir>,
         ctx: &mut impl DowngradeContext<'id, 'ir>,

fix-compiler/src/lib.rs

@@ -1,14 +1,14 @@
-use fix_builtins::{BUILTINS, BuiltinId};
-use fix_common::StringId;
-use fix_ir::{Attr, BinOpKind, Ir, MaybeThunk, Param, RawIrRef, ThunkId, UnOpKind};
+use fix_bytecode::{Const, InstructionPtr, Op, OperandType};
+use fix_lang::StringId;
 use hashbrown::HashMap;
-use num_enum::TryFromPrimitive;
 use rnix::TextRange;
 use string_interner::Symbol as _;
 
-pub mod disassembler;
-
-pub struct InstructionPtr(pub usize);
+mod context;
+pub mod ir;
+pub use context::{CodeState, ExtraScope};
+pub use fix_bytecode::disassembler;
+pub use ir::{Attr, BinOpKind, Ir, MaybeThunk, Param, RawIrRef, ThunkId, UnOpKind};
 
 pub trait BytecodeContext {
     fn intern_string(&mut self, s: &str) -> StringId;
@@ -17,86 +17,6 @@ pub trait BytecodeContext {
     fn get_code_mut(&mut self) -> &mut Vec<u8>;
     fn add_constant(&mut self, val: Const) -> u32;
     fn current_source_dir(&mut self) -> StringId;
-    fn current_scope_slot(&self) -> Option<u32>;
-}
-
-#[repr(u8)]
-#[derive(Debug, Clone, Copy, TryFromPrimitive)]
-#[allow(clippy::enum_variant_names)]
-pub enum Op {
-    PushSmi,
-    PushBigInt,
-    PushFloat,
-    PushString,
-    PushNull,
-    PushTrue,
-    PushFalse,
-
-    LoadLocal,
-    LoadOuter,
-    StoreLocal,
-    AllocLocals,
-
-    MakeThunk,
-    MakeClosure,
-    MakePatternClosure,
-
-    Call,
-    DispatchPrimOp,
-
-    MakeAttrs,
-    MakeEmptyAttrs,
-    SelectStatic,
-    SelectDynamic,
-    HasAttrPathStatic,
-    HasAttrPathDynamic,
-    HasAttrStatic,
-    HasAttrDynamic,
-    HasAttrResolve,
-    JumpIfSelectSucceeded,
-    JumpIfSelectFailed,
-
-    MakeList,
-    MakeEmptyList,
-
-    OpAdd,
-    OpSub,
-    OpMul,
-    OpDiv,
-    OpEq,
-    OpNeq,
-    OpLt,
-    OpGt,
-    OpLeq,
-    OpGeq,
-    OpConcat,
-    OpUpdate,
-
-    OpNeg,
-    OpNot,
-
-    JumpIfFalse,
-    JumpIfTrue,
-    Jump,
-
-    CoerceToString,
-
-    ConcatStrings,
-    ResolvePath,
-
-    Assert,
-
-    LookupWith,
-
-    LoadBuiltins,
-    LoadBuiltin,
-
-    LoadReplBinding,
-    LoadScopedBinding,
-
-    Return,
-
-    Illegal,
 }
 
 struct ScopeInfo {
@@ -109,39 +29,6 @@ struct BytecodeEmitter<'a, Ctx: BytecodeContext> {
     scope_stack: Vec<ScopeInfo>,
 }
 
-#[repr(u8)]
-#[derive(Debug, Clone, Copy, TryFromPrimitive)]
-pub enum OperandType {
-    Const,
-    BigInt,
-    Local,
-    BuiltinConst,
-    Builtins,
-    ReplBinding,
-    ScopedImportBinding,
-}
-
-pub enum Const {
-    Smi(i32),
-    Float(f64),
-    Bool(bool),
-    String(StringId),
-    Path(StringId),
-    PrimOp {
-        id: BuiltinId,
-        arity: u8,
-        dispatch_ip: u32,
-    },
-    Null,
-}
-
-#[repr(u8)]
-#[derive(Debug, Clone, Copy, TryFromPrimitive)]
-pub enum AttrKeyType {
-    Static,
-    Dynamic,
-}
-
 pub enum InlineOperand {
     Const(Const),
     BigInt(i64),
@@ -149,7 +36,7 @@ pub enum InlineOperand {
     BuiltinConst(StringId),
     Builtins,
     ReplBinding(StringId),
-    ScopedImportBinding(StringId),
+    ScopedImportBinding { id: StringId, slot_id: u32 },
 }
 
 pub fn compile_bytecode(ir: RawIrRef<'_>, ctx: &mut impl BytecodeContext) -> InstructionPtr {
@@ -167,7 +54,6 @@ impl<'a, Ctx: BytecodeContext> BytecodeEmitter<'a, Ctx> {
         }
     }
 
-    #[must_use]
     fn inline_maybe_thunk(&self, val: &MaybeThunk) -> InlineOperand {
         use MaybeThunk::*;
         match *val {
@@ -188,18 +74,13 @@ impl<'a, Ctx: BytecodeContext> BytecodeEmitter<'a, Ctx> {
                 InlineOperand::Local { layer, local }
             }
             Arg { layer } => InlineOperand::Local { layer, local: 0 },
-            Builtin(id) => {
-                let (_, arity) = BUILTINS[id as usize];
-                InlineOperand::Const(Const::PrimOp {
-                    id,
-                    arity,
-                    dispatch_ip: id.entry_phase().ip(),
-                })
-            }
+            Builtin(id) => InlineOperand::Const(Const::PrimOp(id)),
             BuiltinConst(id) => InlineOperand::BuiltinConst(id),
             Builtins => InlineOperand::Builtins,
             ReplBinding(id) => InlineOperand::ReplBinding(id),
-            ScopedImportBinding(id) => InlineOperand::ScopedImportBinding(id),
+            ScopedImportBinding { slot_id, sym: id } => {
+                InlineOperand::ScopedImportBinding { slot_id, id }
+            }
         }
     }
 
@@ -232,13 +113,9 @@ impl<'a, Ctx: BytecodeContext> BytecodeEmitter<'a, Ctx> {
                 self.emit_u8(OperandType::ReplBinding as u8);
                 self.emit_str_id(id);
             }
-            ScopedImportBinding(id) => {
+            ScopedImportBinding { id, slot_id } => {
                 self.emit_u8(OperandType::ScopedImportBinding as u8);
-                let slot = self
-                    .ctx
-                    .current_scope_slot()
-                    .expect("ScopedImportBinding outside scoped compilation");
-                self.emit_u32(slot);
+                self.emit_u32(slot_id);
                 self.emit_str_id(id);
             }
         }
@@ -301,6 +178,10 @@ impl<'a, Ctx: BytecodeContext> BytecodeEmitter<'a, Ctx> {
         offset
     }
     #[inline]
+    #[expect(
+        clippy::indexing_slicing,
+        reason = "offset addresses a 4-byte i32 placeholder this compiler previously emitted, so it is in bounds"
+    )]
     fn patch_i32(&mut self, offset: usize, val: i32) {
         self.ctx.get_code_mut()[offset..offset + 4].copy_from_slice(&val.to_le_bytes());
     }
@@ -329,6 +210,10 @@ impl<'a, Ctx: BytecodeContext> BytecodeEmitter<'a, Ctx> {
         self.scope_stack.last().map_or(0, |s| s.depth)
     }
 
+    #[expect(
+        clippy::panic,
+        reason = "a ThunkId must resolve in some enclosing scope; failure indicates a compiler bug"
+    )]
     fn resolve_thunk(&self, id: ThunkId) -> (u8, u32) {
         for scope in self.scope_stack.iter().rev() {
             if let Some(&local_idx) = scope.thunk_map.get(&id) {
@@ -555,14 +440,10 @@ impl<'a, Ctx: BytecodeContext> BytecodeEmitter<'a, Ctx> {
                 self.emit_op(Op::LoadReplBinding);
                 self.emit_str_id(name);
             }
-            &Ir::ScopedImportBinding(name) => {
+            &Ir::ScopedImportBinding { sym, slot_id } => {
                 self.emit_op(Op::LoadScopedBinding);
-                let slot = self
-                    .ctx
-                    .current_scope_slot()
-                    .expect("ScopedImportBinding outside scoped compilation");
-                self.emit_u32(slot);
-                self.emit_str_id(name);
+                self.emit_u32(slot_id);
+                self.emit_str_id(sym);
             }
             Ir::WithLookup { sym, namespaces } => {
                 // counter
@@ -629,20 +510,20 @@ impl<'a, Ctx: BytecodeContext> BytecodeEmitter<'a, Ctx> {
                         self.emit_op(Op::LoadReplBinding);
                         self.emit_str_id(name);
                     }
-                    ScopedImportBinding(name) => {
+                    ScopedImportBinding { slot_id, sym } => {
                         self.emit_op(Op::LoadScopedBinding);
-                        let slot = self
-                            .ctx
-                            .current_scope_slot()
-                            .expect("ScopedImportBinding outside scoped compilation");
-                        self.emit_u32(slot);
-                        self.emit_str_id(name);
+                        self.emit_u32(slot_id);
+                        self.emit_str_id(sym);
                     }
                 }
             }
         }
     }
 
+    #[expect(
+        clippy::unreachable,
+        reason = "the outer match only reaches this arm for the binary operator kinds enumerated above"
+    )]
     fn emit_binop(&mut self, lhs: RawIrRef<'_>, rhs: RawIrRef<'_>, kind: BinOpKind) {
         use BinOpKind::*;
         match kind {
@@ -775,7 +656,7 @@ impl<'a, Ctx: BytecodeContext> BytecodeEmitter<'a, Ctx> {
 
     fn emit_attrset(
         &mut self,
-        stcs: &fix_ir::HashMap<'_, StringId, (&MaybeThunk, TextRange)>,
+        stcs: &ir::HashMap<'_, StringId, (&MaybeThunk, TextRange)>,
         dyns: &[(RawIrRef<'_>, &MaybeThunk, TextRange)],
     ) {
         if stcs.is_empty() && dyns.is_empty() {
@@ -835,14 +716,25 @@ impl<'a, Ctx: BytecodeContext> BytecodeEmitter<'a, Ctx> {
         }
 
         if let Some(default) = default {
-            let before: i32 = self.ctx.get_code().len().try_into().unwrap();
+            // FIXME: i32???
+            let before: i32 = self
+                .ctx
+                .get_code()
+                .len()
+                .try_into()
+                .expect("emitted code length fits in i32");
             for patch in dynamic_patches {
                 self.patch_jump_target(patch);
             }
             self.emit_op(Op::JumpIfSelectSucceeded);
             let placeholder = self.emit_i32_placeholder();
             self.emit_expr(default);
-            let after: i32 = self.ctx.get_code().len().try_into().unwrap();
+            let after: i32 = self
+                .ctx
+                .get_code()
+                .len()
+                .try_into()
+                .expect("emitted code length fits in i32");
             // Offset is relative to after the placeholder, so subtract the
             // size of JumpIfSelectSucceeded (1) + placeholder (4).
             self.patch_i32(placeholder, after - before - 5);
@@ -853,6 +745,10 @@ impl<'a, Ctx: BytecodeContext> BytecodeEmitter<'a, Ctx> {
         }
     }
 
+    #[expect(
+        clippy::panic,
+        reason = "a hasAttr attrpath always has at least one attr by construction of the AST"
+    )]
     fn emit_has_attr(&mut self, lhs: RawIrRef<'_>, rhs: &[Attr<RawIrRef<'_>>]) {
         self.emit_expr(lhs);
 

fix-error/Cargo.toml

@@ -5,5 +5,8 @@ edition = "2024"
 
 [dependencies]
 miette = { version = "7.6", features = ["fancy"] }
-thiserror = "2.0"
 rnix = { workspace = true }
+thiserror = "2.0"
+
+[lints]
+workspace = true

fix-error/src/lib.rs

@@ -4,7 +4,7 @@ use std::sync::Arc;
 use miette::{Diagnostic, NamedSource, SourceSpan};
 use thiserror::Error;
 
-pub type Result<T> = core::result::Result<T, Box<Error>>;
+pub type Result<T, E = Box<Error>> = core::result::Result<T, E>;
 
 #[derive(Clone, Debug)]
 pub enum SourceType {

fix-lang/Cargo.toml

@@ -1,9 +1,13 @@
 [package]
-name = "fix-common"
+name = "fix-lang"
 version = "0.1.0"
 edition = "2024"
 
 [dependencies]
-gc-arena = { workspace = true }
-string-interner = { workspace = true }
 ere = { workspace = true }
+gc-arena = { workspace = true }
+num_enum = { workspace = true }
+string-interner = { workspace = true }
+
+[lints]
+workspace = true

fix-lang/src/lib.rs

@@ -4,6 +4,162 @@ use std::fmt::{Debug, Display, Formatter, Result as FmtResult};
 use std::ops::{Deref, DerefMut};
 
 use gc_arena::Collect;
+use num_enum::TryFromPrimitive;
+
+macro_rules! define_builtins {
+    ($(($name:literal, $variant:ident, $arity:expr)),* $(,)?) => {
+        const BUILTINS: &[(&str, u8)] = &[
+            $(($name, $arity),)*
+        ];
+
+        #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, TryFromPrimitive, Collect)]
+        #[repr(u8)]
+        #[collect(require_static)]
+        pub enum BuiltinId {
+            $($variant,)*
+        }
+
+        impl BuiltinId {
+            pub const ALL: [Self; BUILTINS.len()] = [$(Self::$variant,)*];
+        }
+    };
+}
+
+define_builtins! {
+    ("abort",                    Abort,                    1),
+    ("__add",                      Add,                      2),
+    ("__addErrorContext",          AddErrorContext,           2),
+    ("__all",                      All,                      2),
+    ("__any",                      Any,                      2),
+    ("__appendContext",            AppendContext,             2),
+    ("__attrNames",                AttrNames,                1),
+    ("__attrValues",               AttrValues,               1),
+    ("baseNameOf",               BaseNameOf,               1),
+    ("__bitAnd",                   BitAnd,                   2),
+    ("__bitOr",                    BitOr,                    2),
+    ("__bitXor",                   BitXor,                   2),
+    ("break",                    Break,                    1),
+    ("__catAttrs",                 CatAttrs,                 2),
+    ("__ceil",                     Ceil,                     1),
+    ("__compareVersions",          CompareVersions,          2),
+    ("__concatLists",              ConcatLists,              1),
+    ("__concatMap",                ConcatMap,                2),
+    ("__concatStringsSep",         ConcatStringsSep,         2),
+    ("__convertHash",              ConvertHash,              1),
+    ("__deepSeq",                  DeepSeq,                  2),
+    ("derivation",               Derivation,               1),
+    ("derivationStrict",         DerivationStrict,         1),
+    ("dirOf",                    DirOf,                    1),
+    ("__div",                      Div,                      2),
+    ("__elem",                     Elem,                     2),
+    ("__elemAt",                   ElemAt,                   2),
+    ("fetchGit",                 FetchGit,                 1),
+    ("fetchMercurial",           FetchMercurial,           1),
+    ("fetchTarball",             FetchTarball,             1),
+    ("fetchTree",                FetchTree,                1),
+    ("__fetchurl",                 FetchUrl,                 1),
+    ("__filter",                   Filter,                   2),
+    ("__filterSource",             FilterSource,             2),
+    ("__findFile",                 FindFile,                 2),
+    ("__floor",                    Floor,                    1),
+    ("__foldl'",                   FoldlStrict,              3),
+    ("__fromJSON",                 FromJSON,                 1),
+    ("fromTOML",                 FromTOML,                 1),
+    ("__functionArgs",             FunctionArgs,             1),
+    ("__genList",                  GenList,                  2),
+    ("__genericClosure",           GenericClosure,           1),
+    ("__getAttr",                  GetAttr,                  2),
+    ("__getContext",               GetContext,               1),
+    ("__getEnv",                   GetEnv,                   1),
+    ("__groupBy",                  GroupBy,                  2),
+    ("__hasAttr",                  HasAttr,                  2),
+    ("__hasContext",               HasContext,               1),
+    ("__hashFile",                 HashFile,                 2),
+    ("__hashString",               HashString,               2),
+    ("__head",                     Head,                     1),
+    ("import",                   Import,                   1),
+    ("__intersectAttrs",           IntersectAttrs,           2),
+    ("__isAttrs",                  IsAttrs,                  1),
+    ("__isBool",                   IsBool,                   1),
+    ("__isFloat",                  IsFloat,                  1),
+    ("__isFunction",               IsFunction,               1),
+    ("__isInt",                    IsInt,                    1),
+    ("__isList",                   IsList,                   1),
+    ("isNull",                   IsNull,                   1),
+    ("__isPath",                   IsPath,                   1),
+    ("__isString",                 IsString,                 1),
+    ("__length",                   Length,                   1),
+    ("__lessThan",                 LessThan,                 2),
+    ("__listToAttrs",              ListToAttrs,              1),
+    ("map",                      Map,                      2),
+    ("__mapAttrs",                 MapAttrs,                 2),
+    ("__match",                    Match,                    2),
+    ("__mul",                      Mul,                      2),
+    ("__parseDrvName",             ParseDrvName,             1),
+    ("__partition",                Partition,                2),
+    ("__path",                     Path,                     1),
+    ("__pathExists",               PathExists,               1),
+    ("placeholder",              Placeholder,              1),
+    ("__readDir",                  ReadDir,                  1),
+    ("__readFile",                 ReadFile,                 1),
+    ("__readFileType",             ReadFileType,             1),
+    ("removeAttrs",              RemoveAttrs,              2),
+    ("__replaceStrings",           ReplaceStrings,           3),
+    ("scopedImport",             ScopedImport,             2),
+    ("__seq",                      Seq,                      2),
+    ("__sort",                     Sort,                     2),
+    ("__split",                    Split,                    2),
+    ("__splitVersion",             SplitVersion,             1),
+    ("__storePath",                StorePath,                1),
+    ("__stringLength",             StringLength,             1),
+    ("__sub",                      Sub,                      2),
+    ("__substring",                Substring,                3),
+    ("__tail",                     Tail,                     1),
+    ("throw",                    Throw,                    1),
+    ("__toFile",                   ToFile,                   2),
+    ("__toJSON",                   ToJSON,                   1),
+    ("__toPath",                   ToPath,                   1),
+    ("toString",                 ToString,                 1),
+    ("__toXML",                    ToXML,                    1),
+    ("__trace",                    Trace,                    2),
+    ("__tryEval",                  TryEval,                  1),
+    ("__typeOf",                   TypeOf,                   1),
+    ("__unsafeDiscardStringContext", UnsafeDiscardStringContext, 1),
+    ("__unsafeDiscardOutputDependency", UnsafeDiscardOutputDependency, 1),
+    ("__unsafeGetAttrPos",         UnsafeGetAttrPos,         2),
+    ("__warn",                     Warn,                     2),
+    ("__zipAttrsWith",             ZipAttrsWith,             2),
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub struct BuiltinInfo {
+    pub name: &'static str,
+    pub global_name: &'static str,
+    pub global: bool,
+    pub arity: u8,
+}
+
+impl BuiltinId {
+    pub const TOTAL: usize = BUILTINS.len();
+
+    #[expect(
+        clippy::indexing_slicing,
+        reason = "a `BuiltinId` discriminant is always a valid index into the `BUILTINS` table"
+    )]
+    #[inline(always)]
+    pub fn info(self) -> BuiltinInfo {
+        let (global_name, arity) = BUILTINS[self as usize];
+        let (name, global) = global_name
+            .strip_prefix("__")
+            .map_or((global_name, true), |name| (name, false));
+        BuiltinInfo {
+            name,
+            global_name,
+            global,
+            arity,
+        }
+    }
+}
 
 #[repr(transparent)]
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord, Collect)]
@@ -305,6 +461,10 @@ fn fmt_nix_float(f: &mut Formatter<'_>, x: f64) -> FmtResult {
     let precision: i32 = 6;
     let exp = x.abs().log10().floor() as i32;
 
+    #[expect(
+        clippy::cast_sign_loss,
+        reason = "this branch runs only when exp < precision, so precision-1-exp and precision-1 are non-negative"
+    )]
     let formatted = if exp >= -4 && exp < precision {
         let decimal_places = (precision - 1 - exp) as usize;
         format!("{x:.decimal_places$}")
@@ -329,11 +489,9 @@ fn fmt_nix_float(f: &mut Formatter<'_>, x: f64) -> FmtResult {
     };
 
     if formatted.contains('.') {
-        if let Some(e_pos) = formatted.find('e') {
-            let trimmed = formatted[..e_pos]
-                .trim_end_matches('0')
-                .trim_end_matches('.');
-            write!(f, "{}{}", trimmed, &formatted[e_pos..])
+        if let Some((head, tail)) = formatted.split_once('e') {
+            let trimmed = head.trim_end_matches('0').trim_end_matches('.');
+            write!(f, "{trimmed}e{tail}")
         } else {
             let trimmed = formatted.trim_end_matches('0').trim_end_matches('.');
             write!(f, "{trimmed}")

fix-macros/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "fix-macros"
+version = "0.1.0"
+edition = "2024"
+
+[lib]
+proc-macro = true
+
+[dependencies]
+proc-macro2 = "1.0"
+quote = "1.0"
+syn = { version = "3.0", features = ["full", "visit", "visit-mut"] }
+
+[lints]
+workspace = true

fix-macros/src/lib.rs

@@ -0,0 +1,49 @@
+extern crate proc_macro;
+
+mod handler;
+
+#[proc_macro_attribute]
+pub fn handler(
+    attr: proc_macro::TokenStream,
+    item: proc_macro::TokenStream,
+) -> proc_macro::TokenStream {
+    handler::handler(attr.into(), item.into()).into()
+}
+
+// Adapted from `__unelide_lifetimes` in `gc-arena-derive`.
+// Licensed under the MIT license.
+// See: https://github.com/kyren/gc-arena
+#[proc_macro]
+pub fn unelide_lifetimes(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
+    use quote::ToTokens;
+    use syn::parse::{Parse, ParseStream};
+    use syn::visit_mut::VisitMut;
+
+    struct Input {
+        lt: syn::Lifetime,
+        ty: syn::Type,
+    }
+
+    impl Parse for Input {
+        fn parse(input: ParseStream) -> syn::Result<Self> {
+            let lt: syn::Lifetime = input.parse()?;
+            let _: syn::Token!(;) = input.parse()?;
+            let ty: syn::Type = input.parse()?;
+            Ok(Self { lt, ty })
+        }
+    }
+
+    struct UnelideLifetimes(syn::Lifetime);
+
+    impl VisitMut for UnelideLifetimes {
+        fn visit_lifetime_mut(&mut self, i: &mut syn::Lifetime) {
+            if i.ident == "_" {
+                *i = self.0.clone();
+            }
+        }
+    }
+
+    let mut input = syn::parse_macro_input!(input as Input);
+    UnelideLifetimes(input.lt).visit_type_mut(&mut input.ty);
+    input.ty.to_token_stream().into()
+}

fix-primops/Cargo.toml

@@ -1,17 +0,0 @@
-[package]
-name = "fix-primops"
-version = "0.1.0"
-edition = "2024"
-
-[dependencies]
-gc-arena = { workspace = true }
-hashbrown = { workspace = true }
-num_enum = { workspace = true }
-smallvec = { workspace = true }
-string-interner = { workspace = true }
-
-fix-abstract-vm = { path = "../fix-abstract-vm" }
-fix-builtins = { path = "../fix-builtins" }
-fix-codegen = { path = "../fix-codegen" }
-fix-common = { path = "../fix-common" }
-fix-error = { path = "../fix-error" }

fix-primops/src/lib.rs

@@ -1,87 +0,0 @@
-mod context;
-mod control;
-mod conv;
-mod eq;
-mod io;
-mod list;
-mod path;
-
-pub use context::*;
-pub use control::*;
-pub use conv::*;
-pub use eq::*;
-use fix_abstract_vm::{BytecodeReader, Machine, Step, VmRuntimeCtx};
-use fix_builtins::PrimOpPhase;
-use fix_error::Error;
-use gc_arena::Mutation;
-pub use io::*;
-pub use list::*;
-pub use path::*;
-
-#[allow(clippy::too_many_lines)]
-pub fn dispatch_primop<'gc, M: Machine<'gc>>(
-    m: &mut M,
-    ctx: &mut impl VmRuntimeCtx,
-    reader: &mut BytecodeReader<'_>,
-    mc: &Mutation<'gc>,
-) -> Step {
-    use PrimOpPhase::*;
-    let phase_disc = reader.read_u8();
-    let Ok(phase) = PrimOpPhase::try_from(phase_disc) else {
-        return m.finish_err(Error::eval_error("invalid primop phase"));
-    };
-    match phase {
-        Abort => abort(m, ctx, reader, mc),
-
-        DeepSeq => deep_seq_force_top(m, reader, mc),
-        DeepSeqPush => deep_seq_push(m, reader, mc),
-        DeepSeqLoop => deep_seq_loop(m, reader, mc),
-        Seq => seq(m, reader, mc),
-
-        FilterForceList => filter_force_list(m, reader, mc),
-        FilterCallPred => filter_call_pred(m, reader, mc),
-        FilterCheck => filter_check(m, reader, mc),
-
-        FoldlStrict => foldl_strict_entry(m, reader, mc),
-        FoldlStrictEmpty => foldl_strict_empty(m, reader, mc),
-        FoldlStrictCall1 => foldl_strict_call1(m, reader, mc),
-        FoldlStrictCall2 => foldl_strict_call2(m, reader, mc),
-        FoldlStrictUpdate => foldl_strict_update(m, reader, mc),
-
-        ForceResultShallow => force_result_shallow(m, ctx, reader, mc),
-        ForceResultShallowPush => force_result_shallow_push(m, ctx, reader, mc),
-        ForceResultShallowLoop => force_result_shallow_loop(m, reader, mc),
-        ForceResultDeepFinish => force_result_deep_finish(m, ctx, reader, mc),
-
-        EqStep => eq_step(m, reader, mc),
-        EqForce => eq_force(m, ctx, reader, mc),
-
-        CallPattern => call_pattern(m, ctx, reader, mc),
-        CallFunctor1 => call_functor_1(m, reader, mc),
-        CallFunctor2 => call_functor_2(m, reader, mc),
-
-        Import => import(m, ctx, reader, mc),
-        ImportFinalize => import_finalize(m, ctx, reader),
-        ScopedImport => scoped_import(m, ctx, reader, mc),
-        ScopedImportFinalize => scoped_import_finalize(m, ctx, reader, mc),
-
-        PathExists => path_exists(m, ctx, reader, mc),
-        ToPath => to_path(m, ctx, reader, mc),
-        IsPath => is_path(m, reader, mc),
-        ToString => to_string(m, ctx, reader, mc),
-        TypeOf => type_of(m, ctx, reader, mc),
-
-        HasContext => has_context(m, ctx, reader, mc),
-        GetContext => get_context(m, ctx, reader, mc),
-        AppendContext => append_context(m, ctx, reader, mc),
-        AppendContextLoop => append_context_loop(m, ctx, reader, mc),
-        AppendContextEntryForced => append_context_entry_forced(m, ctx, reader, mc),
-        AppendContextOutputsForced => append_context_outputs_forced(m, ctx, reader, mc),
-        AppendContextOutputElementLoop => append_context_output_element_loop(m, ctx, reader, mc),
-        AppendContextOutputElementForced => append_context_output_element_forced(m, ctx, reader, mc),
-        UnsafeDiscardStringContext => unsafe_discard_string_context(m, ctx, reader, mc),
-        UnsafeDiscardOutputDependency => unsafe_discard_output_dependency(m, ctx, reader, mc),
-
-        phase => todo!("primop phase {phase:?}"),
-    }
-}

fix-primops/src/list.rs

@@ -1,166 +0,0 @@
-use fix_abstract_vm::{
-    BytecodeReader, List, Machine, MachineExt, NixType, Step, StrictValue, Value,
-};
-use fix_builtins::PrimOpPhase;
-use gc_arena::Mutation;
-
-pub fn filter_force_list<'gc, M: Machine<'gc>>(
-    m: &mut M,
-    reader: &mut BytecodeReader<'_>,
-    mc: &Mutation<'gc>,
-) -> Step {
-    m.force_slot(0, reader, mc)?;
-    let list = match m.peek_forced(0).expect_gc::<List>() {
-        Ok(list) => list,
-        Err(got) => return m.finish_type_err(NixType::List, got),
-    };
-    if list.inner.borrow().is_empty() {
-        let val = m.pop();
-        return m.return_from_primop(val, reader);
-    }
-    // prepare stack layout: [ pred list idx acc ]
-    m.push(Value::new_inline(0));
-    m.push(Value::new_gc(List::new_gc(mc)));
-    reader.set_pc(PrimOpPhase::FilterCallPred.ip() as usize);
-    Step::Continue(())
-}
-
-pub fn filter_call_pred<'gc, M: Machine<'gc>>(
-    m: &mut M,
-    reader: &mut BytecodeReader<'_>,
-    mc: &Mutation<'gc>,
-) -> Step {
-    m.force_slot(3, reader, mc)?;
-    let pred = m.peek_forced(3);
-    #[allow(clippy::unwrap_used)]
-    let idx = m.peek(1).as_inline::<i32>().unwrap();
-    #[allow(clippy::unwrap_used)]
-    let elem = m.peek_forced(2).as_gc::<List>().unwrap().inner.borrow()[idx as usize];
-    m.push(pred.relax());
-    m.call(reader, mc, elem, PrimOpPhase::FilterCheck.ip() as usize)
-}
-
-pub fn filter_check<'gc, M: Machine<'gc>>(
-    m: &mut M,
-    reader: &mut BytecodeReader<'_>,
-    mc: &Mutation<'gc>,
-) -> Step {
-    let ret = m.force_and_retry::<bool>(reader, mc)?;
-    #[allow(clippy::unwrap_used)]
-    let idx = m.peek(1).as_inline::<i32>().unwrap();
-    #[allow(clippy::unwrap_used)]
-    let list = m.peek_forced(2).as_gc::<List>().unwrap();
-    let list = list.inner.borrow();
-    #[allow(clippy::unwrap_used)]
-    let acc = m.peek_forced(0).as_gc::<List>().unwrap();
-    if ret {
-        let mut acc = acc.unlock(mc).borrow_mut();
-        acc.push(list[idx as usize]);
-    }
-    if idx as usize == list.len() - 1 {
-        let acc = m.pop();
-        let _ = m.pop(); // idx
-        let _ = m.pop(); // list
-        let _ = m.pop(); // pred
-        return m.return_from_primop(acc, reader);
-    }
-    m.replace(1, Value::new_inline(idx + 1));
-    reader.set_pc(PrimOpPhase::FilterCallPred.ip() as usize);
-    Step::Continue(())
-}
-
-// foldl' op nul list
-//
-// Stack layouts across phases:
-//   Entry:  [op, nul, list]
-//   Empty:  [op, nul]
-//   Call1:  [op, list, idx, acc]
-//   Call2:  [op, list, idx, acc, intermediate]
-//   Update: [op, list, idx, acc, result]
-pub fn foldl_strict_entry<'gc, M: Machine<'gc>>(
-    m: &mut M,
-    reader: &mut BytecodeReader<'_>,
-    mc: &Mutation<'gc>,
-) -> Step {
-    m.force_slot(0, reader, mc)?;
-    let list_val = m.peek_forced(0);
-    let Some(list) = list_val.as_gc::<List>() else {
-        return m.finish_type_err(NixType::List, list_val.ty());
-    };
-    if list.inner.borrow().is_empty() {
-        let _ = m.pop(); // list
-        reader.set_pc(PrimOpPhase::FoldlStrictEmpty.ip() as usize);
-        return Step::Continue(());
-    }
-    let list_val = m.pop();
-    let nul_val = m.pop();
-    m.push(list_val);
-    m.push(Value::new_inline(0i32));
-    m.push(nul_val);
-    reader.set_pc(PrimOpPhase::FoldlStrictCall1.ip() as usize);
-    Step::Continue(())
-}
-
-pub fn foldl_strict_empty<'gc, M: Machine<'gc>>(
-    m: &mut M,
-    reader: &mut BytecodeReader<'_>,
-    mc: &Mutation<'gc>,
-) -> Step {
-    let nul = m.force_and_retry::<StrictValue>(reader, mc)?;
-    let _ = m.pop(); // op
-    m.return_from_primop(nul.relax(), reader)
-}
-
-pub fn foldl_strict_call1<'gc, M: Machine<'gc>>(
-    m: &mut M,
-    reader: &mut BytecodeReader<'_>,
-    mc: &Mutation<'gc>,
-) -> Step {
-    m.force_slot(3, reader, mc)?;
-    let op = m.peek_forced(3);
-    let acc = m.peek(0);
-    m.push(op.relax());
-    m.call(reader, mc, acc, PrimOpPhase::FoldlStrictCall2.ip() as usize)
-}
-
-pub fn foldl_strict_call2<'gc, M: Machine<'gc>>(
-    m: &mut M,
-    reader: &mut BytecodeReader<'_>,
-    mc: &Mutation<'gc>,
-) -> Step {
-    #[allow(clippy::unwrap_used)]
-    let idx = m.peek(2).as_inline::<i32>().unwrap();
-    #[allow(clippy::unwrap_used)]
-    let list = m.peek_forced(3).as_gc::<List>().unwrap();
-    let elem = list.inner.borrow()[idx as usize];
-    m.call(
-        reader,
-        mc,
-        elem,
-        PrimOpPhase::FoldlStrictUpdate.ip() as usize,
-    )
-}
-
-pub fn foldl_strict_update<'gc, M: Machine<'gc>>(
-    m: &mut M,
-    reader: &mut BytecodeReader<'_>,
-    _mc: &Mutation<'gc>,
-) -> Step {
-    let result = m.pop();
-    m.replace(0, result);
-    #[allow(clippy::unwrap_used)]
-    let idx = m.peek(1).as_inline::<i32>().unwrap();
-    #[allow(clippy::unwrap_used)]
-    let list = m.peek_forced(2).as_gc::<List>().unwrap();
-    let len = list.inner.borrow().len();
-    if (idx as usize) + 1 == len {
-        let acc = m.pop();
-        let _ = m.pop(); // idx
-        let _ = m.pop(); // list
-        let _ = m.pop(); // op
-        return m.return_from_primop(acc, reader);
-    }
-    m.replace(1, Value::new_inline(idx + 1));
-    reader.set_pc(PrimOpPhase::FoldlStrictCall1.ip() as usize);
-    Step::Continue(())
-}

fix-runtime/Cargo.toml

@@ -1,18 +1,19 @@
 [package]
-name = "fix-abstract-vm"
+name = "fix-runtime"
 version = "0.1.0"
 edition = "2024"
 
 [dependencies]
 gc-arena = { workspace = true }
 hashbrown = { workspace = true }
-num_enum = { workspace = true }
 smallvec = { workspace = true }
-string-interner = { workspace = true }
-likely_stable = { workspace = true }
 sptr = "0.3"
+string-interner = { workspace = true }
 
-fix-builtins = { path = "../fix-builtins" }
-fix-codegen = { path = "../fix-codegen" }
-fix-common = { path = "../fix-common" }
+fix-bytecode = { path = "../fix-bytecode" }
 fix-error = { path = "../fix-error" }
+fix-lang = { path = "../fix-lang" }
+fix-macros = { path = "../fix-macros" }
+
+[lints]
+workspace = true

fix-runtime/src/boxing.rs

@@ -1,4 +1,7 @@
-#![allow(dead_code)]
+#![allow(
+    dead_code,
+    reason = "boxing layer exposes a full API surface; some helpers are used only on specific targets or not yet wired up"
+)]
 
 use std::fmt;
 use std::num::NonZeroU8;
@@ -79,41 +82,48 @@ int_store!(i16);
 int_store!(i32);
 
 fn store_ptr<P: Strict + Copy>(value: &mut Value, ptr: P) {
-    #[cfg(target_pointer_width = "64")]
-    {
+    cfg_select! {
+        target_pointer_width = "64" => {
             assert!(
                 ptr.addr() <= 0x0000_FFFF_FFFF_FFFF,
                 "Pointer too large to store in NaN box"
             );
 
+            // SAFETY: `Value` is `#[repr(C, align(8))]` and exactly 8 bytes, so it is
+            // sound to reinterpret its storage as a `[u8; 8]` that we then treat as `P`
+            // (a pointer-sized value).
             let val = (unsafe { value.whole_mut() } as *mut [u8; 8]).cast::<P>();
 
             let ptr = Strict::map_addr(ptr, |addr| {
                 addr | (usize::from(value.header().into_raw()) << 48)
             });
 
+            // SAFETY: `val` points to the `Value`'s 8-byte storage, which is valid and
+            // suitably aligned to hold `P`.
             unsafe { val.write(ptr) };
         }
-
-    #[cfg(target_pointer_width = "32")]
-    {
-        let _ = (value, ptr);
-        unimplemented!("32-bit pointer storage not supported");
+        _ => {
+            compile_error!("unsupported pointer width");
+        }
     }
 }
 
 fn load_ptr<P: Strict>(value: &Value) -> P {
-    #[cfg(target_pointer_width = "64")]
-    {
+    cfg_select! {
+        target_pointer_width = "64" => {
+            // SAFETY: `Value` is `#[repr(C, align(8))]` and exactly 8 bytes, so it
+            // is sound to reinterpret its storage as a `[u8; 8]` cast to `P`; the
+            // pointer was originally written through this same `P` layout by
+            // `store_ptr`.
             let val = (unsafe { value.whole() } as *const [u8; 8]).cast::<P>();
+            // SAFETY: `val` points to the `Value`'s 8-byte storage, which is valid
+            // and suitably aligned to hold `P`.
             let ptr = unsafe { val.read() };
             Strict::map_addr(ptr, |addr| addr & 0x0000_FFFF_FFFF_FFFF)
         }
-
-    #[cfg(target_pointer_width = "32")]
-    {
-        let _ = value;
-        unimplemented!("32-bit pointer storage not supported");
+        _ => {
+            compile_error!("unsupported pointer width");
+        }
     }
 }
 
@@ -179,6 +189,10 @@ impl RawTag {
     #[inline]
     #[must_use]
     pub(crate) fn new(neg: bool, val: NonZeroU8) -> RawTag {
+        // SAFETY: masking a `NonZeroU8` with `0x07` yields a value in `0..8`;
+        // callers only construct tags from valid tag discriminants in `1..8`,
+        // so the low three bits are in the `1..8` range required by
+        // `new_unchecked`.
         unsafe { Self::new_unchecked(neg, val.get() & 0x07) }
     }
 
@@ -229,6 +243,9 @@ impl RawTag {
             (true, 6) => TagVal::_N6,
             (true, 7) => TagVal::_N7,
 
+            // SAFETY: the caller guarantees `val` is in `1..8`; every
+            // `(neg, val)` combination in that range is matched above, so this
+            // arm cannot be reached.
             _ => unsafe { core::hint::unreachable_unchecked() },
         })
     }
@@ -302,6 +319,10 @@ impl Header {
 
     #[inline]
     const fn tag(self) -> RawTag {
+        // SAFETY: a `Header` is only ever constructed by `Header::new` from a
+        // `RawTag` whose value is in `1..8`, stored in the low three bits;
+        // `get_tag` recovers exactly those bits, so the argument passed to
+        // `new_unchecked` is in the required `1..8` range.
         unsafe { RawTag::new_unchecked(self.get_sign(), self.get_tag()) }
     }
 
@@ -323,7 +344,7 @@ impl Header {
 
 #[derive(Copy, Clone, Debug, PartialEq)]
 #[repr(C, align(8))]
-pub struct Value {
+pub(crate) struct Value {
     #[cfg(target_endian = "big")]
     header: Header,
     data: [u8; 6],
@@ -387,6 +408,9 @@ impl Value {
     #[must_use]
     unsafe fn whole(&self) -> &[u8; 8] {
         let ptr = (self as *const Value).cast::<[u8; 8]>();
+        // SAFETY: `Value` is `#[repr(C, align(8))]` and exactly 8 bytes with no
+        // padding, so it shares its layout with `[u8; 8]`; `ptr` is derived
+        // from a valid `&Value`, so the reference is valid for reads.
         unsafe { &*ptr }
     }
 
@@ -394,6 +418,10 @@ impl Value {
     #[must_use]
     unsafe fn whole_mut(&mut self) -> &mut [u8; 8] {
         let ptr = (self as *mut Value).cast::<[u8; 8]>();
+        // SAFETY: `Value` is `#[repr(C, align(8))]` and exactly 8 bytes with no
+        // padding, so it shares its layout with `[u8; 8]`; `ptr` is derived
+        // from a unique `&mut Value`, so the reference is valid for reads and
+        // writes.
         unsafe { &mut *ptr }
     }
 }
@@ -435,6 +463,9 @@ impl RawBox {
     #[must_use]
     pub(crate) const fn tag(&self) -> Option<RawTag> {
         if self.is_value() {
+            // SAFETY: `is_value()` returned true, so the union holds a `Value`
+            // (a tagged-NaN bit pattern) rather than a float, making the read
+            // of the `value` field sound.
             Some(unsafe { self.value.tag() })
         } else {
             None
@@ -444,12 +475,18 @@ impl RawBox {
     #[inline]
     #[must_use]
     pub(crate) fn is_float(&self) -> bool {
+        // SAFETY: every 8-byte pattern is simultaneously a valid `f64` and a
+        // valid `u64`, so reading the `float` and `bits` union fields is
+        // always sound.
         (unsafe { !self.float.is_nan() } || unsafe { self.bits & SIGN_MASK == QUIET_NAN })
     }
 
     #[inline]
     #[must_use]
     pub(crate) const fn is_value(&self) -> bool {
+        // SAFETY: every 8-byte pattern is simultaneously a valid `f64` and a
+        // valid `u64`, so reading the `float` and `bits` union fields is
+        // always sound.
         (unsafe { self.float.is_nan() } && unsafe { self.bits & SIGN_MASK != QUIET_NAN })
     }
 
@@ -457,6 +494,8 @@ impl RawBox {
     #[must_use]
     pub(crate) fn float(&self) -> Option<&f64> {
         if self.is_float() {
+            // SAFETY: reading the `float` field is sound because any 8-byte
+            // pattern is a valid `f64`.
             Some(unsafe { &self.float })
         } else {
             None
@@ -467,6 +506,9 @@ impl RawBox {
     #[must_use]
     pub(crate) fn value(&self) -> Option<&Value> {
         if self.is_value() {
+            // SAFETY: `is_value()` returned true, so the union holds a `Value`;
+            // `Value` has no invalid bit patterns, so reading the `value` field
+            // is sound.
             Some(unsafe { &self.value })
         } else {
             None
@@ -475,12 +517,16 @@ impl RawBox {
 
     #[inline]
     pub(crate) fn into_float_unchecked(self) -> f64 {
+        // SAFETY: reading the `float` field is sound because any 8-byte pattern
+        // is a valid `f64`.
         unsafe { self.float }
     }
 
     #[inline]
     #[must_use]
     pub(crate) fn to_bits(self) -> u64 {
+        // SAFETY: reading the `bits` field is sound because any 8-byte pattern
+        // is a valid `u64`.
         unsafe { self.bits }
     }
 }

fix-runtime/src/forced.rs

@@ -1,9 +1,9 @@
-use fix_common::StringId;
-use gc_arena::{Gc, Mutation};
+use fix_lang::StringId;
+use gc_arena::Mutation;
 
 use crate::{
-    AttrSet, Break, BytecodeReader, Closure, List, Machine, NixNum, NixString, NixType, Null,
-    PrimOp, PrimOpApp, Step, StrictValue,
+    AttrSet, BytecodeReader, Closure, List, Machine, NixNum, NixString, NixType, Null, PrimOp,
+    PrimOpApp, Step, StrictValue, ValueVariant,
 };
 
 pub trait Forced<'gc>: Sized {
@@ -47,10 +47,10 @@ impl<'gc> Forced<'gc> for StrictValue<'gc> {
     }
 }
 
-macro_rules! impl_forced_inline {
-    ($($ty:ty => $nix_ty:expr),* $(,)?) => {
+macro_rules! impl_forced {
+    ($($ty:ty),* $(,)?) => {
         $(
-        impl<'gc> Forced<'gc> for $ty {
+        impl<'gc> Forced<'gc> for <$ty as ValueVariant<'gc>>::Ty {
             const WIDTH: usize = 1;
 
             #[inline(always)]
@@ -63,17 +63,17 @@ macro_rules! impl_forced_inline {
             ) -> Step {
                 m.force_slot_to_pc(base_depth, reader, mc, resume_pc)?;
                 let v = m.peek_forced(base_depth);
-                if v.as_inline::<$ty>().is_none() {
-                    let _: Step = m.finish_type_err($nix_ty, v.ty());
-                    return Step::Break(Break::Done);
-                }
+                if !v.is::<$ty>() {
+                    m.finish_type_err(<$ty as ValueVariant>::TYPE, v.ty())
+                } else {
                     Step::Continue(())
                 }
+            }
 
             #[inline(always)]
             fn pop_converted<M: Machine<'gc>>(m: &mut M) -> Self {
                 m.pop_forced()
-                    .as_inline::<$ty>()
+                    .downcast::<$ty>()
                     .expect("type checked in force_and_check")
             }
         }
@@ -81,55 +81,18 @@ macro_rules! impl_forced_inline {
     };
 }
 
-macro_rules! impl_forced_gc {
-    ($($ty:ty => $nix_ty:expr),* $(,)?) => {
-        $(
-        impl<'gc> Forced<'gc> for Gc<'gc, $ty> {
-            const WIDTH: usize = 1;
-
-            #[inline(always)]
-            fn force_and_check<M: Machine<'gc>>(
-                m: &mut M,
-                reader: &mut BytecodeReader<'_>,
-                mc: &Mutation<'gc>,
-                base_depth: usize,
-                resume_pc: usize,
-            ) -> Step {
-                m.force_slot_to_pc(base_depth, reader, mc, resume_pc)?;
-                let v = m.peek_forced(base_depth);
-                if v.as_gc::<$ty>().is_none() {
-                    let _: Step = m.finish_type_err($nix_ty, v.ty());
-                    return Step::Break(Break::Done);
-                }
-                Step::Continue(())
-            }
-
-            #[inline(always)]
-            fn pop_converted<M: Machine<'gc>>(m: &mut M) -> Self {
-                m.pop_forced()
-                    .as_gc::<$ty>()
-                    .expect("type checked in force_and_check")
-            }
-        }
-        )*
-    };
-}
-
-impl_forced_inline! {
-    i32 => NixType::Int,
-    bool => NixType::Bool,
-    Null => NixType::Null,
-    StringId => NixType::String,
-    PrimOp => NixType::PrimOp,
-}
-
-impl_forced_gc! {
-    i64 => NixType::Int,
-    NixString => NixType::String,
-    AttrSet<'gc> => NixType::AttrSet,
-    List<'gc> => NixType::List,
-    Closure<'gc> => NixType::Closure,
-    PrimOpApp<'gc> => NixType::PrimOpApp,
+impl_forced! {
+    i32,
+    bool,
+    Null,
+    StringId,
+    PrimOp,
+    i64,
+    NixString,
+    AttrSet<'gc>,
+    List<'gc>,
+    Closure<'gc>,
+    PrimOpApp<'gc>,
 }
 
 impl<'gc> Forced<'gc> for NixNum {
@@ -145,17 +108,17 @@ impl<'gc> Forced<'gc> for NixNum {
     ) -> Step {
         m.force_slot_to_pc(base_depth, reader, mc, resume_pc)?;
         let v = m.peek_forced(base_depth);
-        if v.as_num().is_none() {
-            let _: Step = m.finish_type_err(NixType::Int, v.ty());
-            return Step::Break(Break::Done);
-        }
+        if v.downcast_num().is_none() {
+            m.finish_type_err(NixType::Int, v.ty())
+        } else {
             Step::Continue(())
         }
+    }
 
     #[inline(always)]
     fn pop_converted<M: Machine<'gc>>(m: &mut M) -> Self {
         m.pop_forced()
-            .as_num()
+            .downcast_num()
             .expect("type checked in force_and_check")
     }
 }
@@ -173,17 +136,17 @@ impl<'gc> Forced<'gc> for f64 {
     ) -> Step {
         m.force_slot_to_pc(base_depth, reader, mc, resume_pc)?;
         let v = m.peek_forced(base_depth);
-        if v.as_float().is_none() {
-            let _: Step = m.finish_type_err(NixType::Float, v.ty());
-            return Step::Break(Break::Done);
-        }
+        if !v.is::<f64>() {
+            m.finish_type_err(NixType::Float, v.ty())
+        } else {
             Step::Continue(())
         }
+    }
 
     #[inline(always)]
     fn pop_converted<M: Machine<'gc>>(m: &mut M) -> Self {
         m.pop_forced()
-            .as_float()
+            .downcast::<f64>()
             .expect("type checked in force_and_check")
     }
 }

fix-runtime/src/host.rs

@@ -1,10 +1,11 @@
-use fix_codegen::InstructionPtr;
-use fix_common::StringId;
+use fix_bytecode::InstructionPtr;
 use fix_error::Source;
+use fix_lang::{self, StringId};
 use hashbrown::HashSet;
 
 use crate::{
-    AttrSet, Closure, ExtraScope, List, NixString, NixType, Null, Path, PrimOp, PrimOpApp, StaticValue, StrictValue, StringContext, Thunk, ThunkState, Value
+    AttrSet, Closure, ExtraScope, List, NixString, NixType, Null, Path, PrimOp, PrimOpApp,
+    StaticValue, StrictValue, StringContext, Thunk, ThunkState, Value,
 };
 
 pub trait VmContext {
@@ -38,15 +39,15 @@ pub trait VmRuntimeCtxExt: VmRuntimeCtx {
     /// Returns the string context attached to `val`, or `&[]` if `val` is
     /// either a non-string or a string without context.
     fn get_string_context<'gc>(&self, val: StrictValue<'gc>) -> &'gc StringContext;
-    fn convert_value(&self, val: Value) -> fix_common::Value;
+    fn convert_value(&self, val: Value) -> fix_lang::Value;
 }
 
 impl<T: VmRuntimeCtx> VmRuntimeCtxExt for T {
     fn get_string<'a, 'gc: 'a>(&'a self, val: StrictValue<'gc>) -> Option<&'a str> {
-        if let Some(sid) = val.as_inline::<StringId>() {
+        if let Some(sid) = val.downcast::<StringId>() {
             Some(self.resolve_string(sid))
         } else {
-            val.as_gc::<NixString>().map(|ns| ns.as_ref().as_str())
+            val.downcast::<NixString>().map(|ns| ns.as_ref().as_str())
         }
     }
 
@@ -55,7 +56,7 @@ impl<T: VmRuntimeCtx> VmRuntimeCtxExt for T {
     /// would coerce a path to a string (string interpolation, file IO
     /// builtins, etc.).
     fn get_string_or_path<'a, 'gc: 'a>(&'a self, val: StrictValue<'gc>) -> Option<&'a str> {
-        if let Some(p) = val.as_inline::<Path>() {
+        if let Some(p) = val.downcast::<Path>() {
             Some(self.resolve_string(p.0))
         } else {
             self.get_string(val)
@@ -66,9 +67,9 @@ impl<T: VmRuntimeCtx> VmRuntimeCtxExt for T {
         &'a mut self,
         val: StrictValue<'gc>,
     ) -> std::result::Result<StringId, NixType> {
-        if let Some(sid) = val.as_inline::<StringId>() {
+        if let Some(sid) = val.downcast::<StringId>() {
             Ok(sid)
-        } else if let Some(s) = val.as_gc::<NixString>().map(|ns| ns.as_ref().as_str()) {
+        } else if let Some(s) = val.downcast::<NixString>().map(|ns| ns.as_ref().as_str()) {
             Ok(self.intern_string(s))
         } else {
             Err(val.ty())
@@ -76,43 +77,43 @@ impl<T: VmRuntimeCtx> VmRuntimeCtxExt for T {
     }
 
     fn get_string_context<'gc>(&self, val: StrictValue<'gc>) -> &'gc StringContext {
-        if let Some(ns) = val.as_gc::<NixString>() {
+        if let Some(ns) = val.downcast::<NixString>() {
             ns.as_ref().context()
         } else {
             StringContext::empty()
         }
     }
 
-    fn convert_value(&self, val: Value) -> fix_common::Value {
+    fn convert_value(&self, val: Value) -> fix_lang::Value {
         self.convert_value_with_seen(val, &mut HashSet::new())
     }
 }
 
 pub(crate) trait ConvertValueWithSeen: VmRuntimeCtx {
-    fn convert_value_with_seen(&self, val: Value, seen: &mut HashSet<u64>) -> fix_common::Value;
+    fn convert_value_with_seen(&self, val: Value, seen: &mut HashSet<u64>) -> fix_lang::Value;
 }
 
 impl<T: VmRuntimeCtx> ConvertValueWithSeen for T {
-    fn convert_value_with_seen(&self, val: Value, seen: &mut HashSet<u64>) -> fix_common::Value {
-        use fix_common::Value;
-        if let Some(i) = val.as_inline::<i32>() {
+    fn convert_value_with_seen(&self, val: Value, seen: &mut HashSet<u64>) -> fix_lang::Value {
+        use fix_lang::Value;
+        if let Some(i) = val.downcast::<i32>() {
             Value::Int(i as i64)
-        } else if let Some(gc_i) = val.as_gc::<i64>() {
+        } else if let Some(gc_i) = val.downcast::<i64>() {
             Value::Int(*gc_i)
-        } else if let Some(f) = val.as_float() {
+        } else if let Some(f) = val.downcast::<f64>() {
             Value::Float(f)
-        } else if let Some(b) = val.as_inline::<bool>() {
+        } else if let Some(b) = val.downcast::<bool>() {
             Value::Bool(b)
         } else if val.is::<Null>() {
             Value::Null
-        } else if let Some(sid) = val.as_inline::<StringId>() {
+        } else if let Some(sid) = val.downcast::<StringId>() {
             let s = self.resolve_string(sid).to_owned();
             Value::String(s)
-        } else if let Some(ns) = val.as_gc::<NixString>() {
+        } else if let Some(ns) = val.downcast::<NixString>() {
             Value::String(ns.as_str().to_owned())
-        } else if let Some(p) = val.as_inline::<Path>() {
+        } else if let Some(p) = val.downcast::<Path>() {
             Value::Path(self.resolve_string(p.0).to_owned())
-        } else if let Some(attrs) = val.as_gc::<AttrSet>() {
+        } else if let Some(attrs) = val.downcast::<AttrSet>() {
             let bits = val.to_bits();
             if attrs.entries.is_empty() {
                 return Value::AttrSet(Default::default());
@@ -124,10 +125,10 @@ impl<T: VmRuntimeCtx> ConvertValueWithSeen for T {
             for &(key, val) in attrs.entries.iter() {
                 let key = self.resolve_string(key).to_owned();
                 let converted = self.convert_value_with_seen(val, seen);
-                map.insert(fix_common::Symbol::from(key), converted);
+                map.insert(fix_lang::Symbol::from(key), converted);
             }
-            Value::AttrSet(fix_common::AttrSet::new(map))
-        } else if let Some(list) = val.as_gc::<List>() {
+            Value::AttrSet(fix_lang::AttrSet::new(map))
+        } else if let Some(list) = val.downcast::<List>() {
             let bits = val.to_bits();
             if list.inner.borrow().is_empty() {
                 return Value::List(Default::default());
@@ -142,21 +143,19 @@ impl<T: VmRuntimeCtx> ConvertValueWithSeen for T {
                 .copied()
                 .map(|v| self.convert_value_with_seen(v, seen))
                 .collect();
-            Value::List(fix_common::List::new(items))
+            Value::List(fix_lang::List::new(items))
         } else if val.is::<Closure>() {
             Value::Func
-        } else if let Some(thunk) = val.as_gc::<Thunk>() {
+        } else if let Some(thunk) = val.downcast::<Thunk>() {
             if let ThunkState::Evaluated(v) = *thunk.borrow() {
                 self.convert_value_with_seen(v.relax(), seen)
             } else {
                 Value::Thunk
             }
-        } else if let Some(primop) = val.as_inline::<PrimOp>() {
-            let name = fix_builtins::BUILTINS[primop.id as usize].0;
-            Value::PrimOp(name.strip_prefix("__").unwrap_or(name))
-        } else if let Some(app) = val.as_gc::<PrimOpApp>() {
-            let name = fix_builtins::BUILTINS[app.primop.id as usize].0;
-            Value::PrimOpApp(name.strip_prefix("__").unwrap_or(name))
+        } else if let Some(primop) = val.downcast::<PrimOp>() {
+            Value::PrimOp(primop.id.info().name)
+        } else if let Some(app) = val.downcast::<PrimOpApp>() {
+            Value::PrimOpApp(app.primop.id.info().name)
         } else {
             Value::Null
         }

fix-runtime/src/lib.rs

@@ -1,20 +1,23 @@
 mod boxing;
-mod bytecode_reader;
 mod forced;
 mod host;
 mod machine;
+mod macro_support;
 mod path_util;
 mod resolve;
+mod slot;
 mod state;
 mod string_context;
 mod value;
 
-pub use bytecode_reader::*;
+pub use fix_bytecode::{BytecodeReader, OperandData};
 pub use forced::*;
 pub use host::*;
 pub use machine::*;
+pub use macro_support::*;
 pub use path_util::*;
 pub use resolve::*;
+pub use slot::*;
 pub use state::*;
 pub use string_context::*;
 pub use value::*;

fix-runtime/src/machine.rs

@@ -1,13 +1,13 @@
 use std::ops::ControlFlow;
 use std::path::{Path, PathBuf};
 
-use fix_common::StringId;
 use fix_error::Error;
-use gc_arena::Mutation;
+use fix_lang::{self, StringId};
+use gc_arena::{Gc, Mutation};
 
 use crate::{
-    Break, BytecodeReader, CallFrame, ForceMode, Forced, GcEnv, NixType, PendingLoad, Step,
-    StrictValue, Value, VmError,
+    AttrSet, Break, BytecodeReader, CallFrame, ForceMode, Forced, GcEnv, NixType, PendingLoad,
+    Step, StrictValue, Value, VmError,
 };
 
 /// Abstract VM-side operations consumed by instruction handlers and primops.
@@ -26,11 +26,15 @@ use crate::{
 /// - Imports and scope slots (`import_cache_*` / `scope_slot*` / `set_pending_load`)
 pub trait Machine<'gc> {
     fn push(&mut self, val: Value<'gc>);
+    #[must_use]
     fn pop(&mut self) -> Value<'gc>;
+    #[must_use]
     fn peek(&self, depth: usize) -> Value<'gc>;
+    #[must_use]
     fn peek_forced(&self, depth: usize) -> StrictValue<'gc>;
     fn pop_forced(&mut self) -> StrictValue<'gc>;
     fn replace(&mut self, depth: usize, val: Value<'gc>);
+    fn drop_n(&mut self, depth: usize);
     fn stack_len(&self) -> usize;
 
     fn force_slot_to_pc(
@@ -61,12 +65,17 @@ pub trait Machine<'gc> {
     ) -> Step;
 
     #[inline(always)]
+    #[expect(
+        clippy::unreachable,
+        reason = "a primop only returns via `return_from_primop` while its call frame is still on the stack, so `pop_call_frame` is always `Some`"
+    )]
     fn return_from_primop(&mut self, val: Value<'gc>, reader: &mut BytecodeReader<'_>) -> Step {
         self.push(val);
         let Some(CallFrame {
             pc: ret_pc,
             thunk: _,
             env,
+            depth: None,
         }) = self.pop_call_frame()
         else {
             unreachable!()
@@ -87,6 +96,10 @@ pub trait Machine<'gc> {
     fn set_env(&mut self, env: GcEnv<'gc>);
 
     #[inline(always)]
+    #[expect(
+        clippy::indexing_slicing,
+        reason = "codegen guarantees the local index is within the resolved frame's `locals`"
+    )]
     fn local(&self, layer: u8, idx: u32) -> Value<'gc> {
         let mut cur = self.env();
         for _ in 0..layer {
@@ -96,7 +109,7 @@ pub trait Machine<'gc> {
         cur.borrow().locals[idx as usize]
     }
 
-    fn finish_ok(&mut self, val: fix_common::Value) -> Step;
+    fn finish_ok(&mut self, val: fix_lang::Value) -> Step;
     fn finish_err(&mut self, err: Box<Error>) -> Step;
     fn finish_type_err(&mut self, expected: NixType, got: NixType) -> Step;
 
@@ -105,7 +118,7 @@ pub trait Machine<'gc> {
         self.finish_err(err.into_error())
     }
 
-    fn builtins(&self) -> Value<'gc>;
+    fn builtins(&self) -> Gc<'gc, AttrSet<'gc>>;
     fn functor_sym(&self) -> StringId;
     fn empty_list(&self) -> Value<'gc>;
     fn empty_attrs(&self) -> Value<'gc>;

fix-runtime/src/macro_support.rs

@@ -0,0 +1,165 @@
+use std::ops::ControlFlow;
+
+use gc_arena::Mutation;
+
+use crate::{
+    Break, BytecodeReader, Forced, Machine, MachineExt, Slot, SlotContent, Step, StrictValue,
+    Value, ValueVariant,
+};
+
+pub trait UnwrapSlot {
+    type Unwrapped;
+}
+
+impl<T> UnwrapSlot for Slot<T> {
+    type Unwrapped = T;
+}
+
+/// Force-target protocol behind the `#[primop]` `force` form: `Value` only
+/// needs WHNF, `StrictValue` *is* WHNF, and content types are checked through
+/// [`Forced`] on their stored representation.
+pub trait ForceTarget<'gc>: SlotContent<'gc> {
+    /// Type-check the stack slot refined by the previous `force(slot)`; the
+    /// slot is already WHNF when this runs.
+    fn refine_check<M: Machine<'gc>>(
+        m: &mut M,
+        reader: &mut BytecodeReader<'_>,
+        mc: &Mutation<'gc>,
+        depth: usize,
+    ) -> Step;
+
+    /// Pop and convert the previous suspension's result into the annotated
+    /// binding's stored representation.
+    fn conv_force<M: Machine<'gc>>(
+        m: &mut M,
+        reader: &mut BytecodeReader<'_>,
+        mc: &Mutation<'gc>,
+    ) -> ControlFlow<Break, <Self as SlotContent<'gc>>::Ty>;
+}
+
+impl<'gc> ForceTarget<'gc> for Value<'gc> {
+    #[inline(always)]
+    fn refine_check<M: Machine<'gc>>(
+        _m: &mut M,
+        _reader: &mut BytecodeReader<'_>,
+        _mc: &Mutation<'gc>,
+        _depth: usize,
+    ) -> Step {
+        Step::Continue(())
+    }
+
+    #[inline(always)]
+    fn conv_force<M: Machine<'gc>>(
+        m: &mut M,
+        reader: &mut BytecodeReader<'_>,
+        mc: &Mutation<'gc>,
+    ) -> ControlFlow<Break, Value<'gc>> {
+        match m.force_and_retry::<StrictValue<'gc>>(reader, mc) {
+            ControlFlow::Continue(v) => ControlFlow::Continue(v.relax()),
+            ControlFlow::Break(b) => ControlFlow::Break(b),
+        }
+    }
+}
+
+impl<'gc> ForceTarget<'gc> for StrictValue<'gc> {
+    #[inline(always)]
+    fn refine_check<M: Machine<'gc>>(
+        _m: &mut M,
+        _reader: &mut BytecodeReader<'_>,
+        _mc: &Mutation<'gc>,
+        _depth: usize,
+    ) -> Step {
+        Step::Continue(())
+    }
+
+    #[inline(always)]
+    fn conv_force<M: Machine<'gc>>(
+        m: &mut M,
+        reader: &mut BytecodeReader<'_>,
+        mc: &Mutation<'gc>,
+    ) -> ControlFlow<Break, StrictValue<'gc>> {
+        m.force_and_retry::<StrictValue<'gc>>(reader, mc)
+    }
+}
+
+impl<'gc, T> ForceTarget<'gc> for T
+where
+    T: ValueVariant<'gc>,
+    <T as ValueVariant<'gc>>::Ty: Forced<'gc>,
+{
+    #[inline(always)]
+    fn refine_check<M: Machine<'gc>>(
+        m: &mut M,
+        reader: &mut BytecodeReader<'_>,
+        mc: &Mutation<'gc>,
+        depth: usize,
+    ) -> Step {
+        <<T as ValueVariant<'gc>>::Ty as Forced<'gc>>::force_and_check(
+            m,
+            reader,
+            mc,
+            depth,
+            reader.inst_start_pc(),
+        )
+    }
+
+    #[inline(always)]
+    fn conv_force<M: Machine<'gc>>(
+        m: &mut M,
+        reader: &mut BytecodeReader<'_>,
+        mc: &Mutation<'gc>,
+    ) -> ControlFlow<Break, <T as SlotContent<'gc>>::Ty> {
+        m.force_and_retry::<<T as ValueVariant<'gc>>::Ty>(reader, mc)
+    }
+}
+
+/// Callee protocol behind `call(&slot, ..)`: an unforced `Slot<Value>` is
+/// WHNF'd before the call; refined slots already hold strict values.
+pub trait CalleeReady<'gc> {
+    fn callee_ready<M: Machine<'gc>>(
+        &self,
+        m: &mut M,
+        reader: &mut BytecodeReader<'_>,
+        mc: &Mutation<'gc>,
+    ) -> ControlFlow<Break>;
+}
+
+impl<'gc> CalleeReady<'gc> for Slot<Value<'gc>> {
+    #[inline(always)]
+    fn callee_ready<M: Machine<'gc>>(
+        &self,
+        m: &mut M,
+        reader: &mut BytecodeReader<'_>,
+        mc: &Mutation<'gc>,
+    ) -> ControlFlow<Break> {
+        self.force::<StrictValue<'gc>, M>(m, reader, mc)?;
+        ControlFlow::Continue(())
+    }
+}
+
+impl<'gc> CalleeReady<'gc> for Slot<StrictValue<'gc>> {
+    #[inline(always)]
+    fn callee_ready<M: Machine<'gc>>(
+        &self,
+        _m: &mut M,
+        _reader: &mut BytecodeReader<'_>,
+        _mc: &Mutation<'gc>,
+    ) -> ControlFlow<Break> {
+        ControlFlow::Continue(())
+    }
+}
+
+impl<'gc, T> CalleeReady<'gc> for Slot<T>
+where
+    T: ValueVariant<'gc>,
+{
+    #[inline(always)]
+    fn callee_ready<M: Machine<'gc>>(
+        &self,
+        _m: &mut M,
+        _reader: &mut BytecodeReader<'_>,
+        _mc: &Mutation<'gc>,
+    ) -> ControlFlow<Break> {
+        ControlFlow::Continue(())
+    }
+}

fix-runtime/src/resolve.rs

@@ -1,6 +1,7 @@
+use fix_bytecode::OperandData;
 use gc_arena::{Gc, Mutation};
 
-use crate::{AttrSet, Machine, OperandData, Value};
+use crate::{AttrSet, Machine, Value, VmRuntimeCtx};
 
 /// Resolve a decoded operand into a runtime [`Value`].
 ///
@@ -11,22 +12,20 @@ use crate::{AttrSet, Machine, OperandData, Value};
 pub fn resolve_operand<'gc, M: Machine<'gc>>(
     op: &OperandData,
     mc: &Mutation<'gc>,
+    ctx: &impl VmRuntimeCtx,
     m: &M,
 ) -> Value<'gc> {
     use OperandData::*;
     match *op {
-        Const(sv) => sv.into(),
-        BigInt(val) => Value::new_gc(Gc::new(mc, val)),
+        Const(id) => ctx.get_const(id).into(),
+        BigInt(val) => Value::new(Gc::new(mc, val)),
         Local { layer, idx } => m.local(layer, idx),
-        #[allow(clippy::unwrap_used)]
-        BuiltinConst(id) => m.builtins().as_gc::<AttrSet>().unwrap().lookup(id).unwrap(),
-        Builtins => m.builtins(),
+        BuiltinConst(id) => m.builtins().lookup(id).expect("builtin const must exist"),
+        Builtins => m.builtins().into(),
         ReplBinding(_id) => todo!(),
         ScopedImportBinding { slot_id, name } => {
             let scope = m.scope_slot(slot_id);
-            #[allow(clippy::unwrap_used)]
-            let attrs = scope.as_gc::<AttrSet>().expect("scope must be attrset");
-            #[allow(clippy::unwrap_used)]
+            let attrs = scope.downcast::<AttrSet>().expect("scope must be attrset");
             attrs.lookup(name).expect("scoped binding not found")
         }
     }

fix-runtime/src/slot.rs

@@ -0,0 +1,86 @@
+use std::marker::PhantomData;
+use std::ops::ControlFlow;
+
+use fix_bytecode::BytecodeReader;
+use gc_arena::Mutation;
+
+use crate::{Break, Forced, Machine, NixType, Step, StrictValue, Value, ValueVariant};
+
+pub struct TypeError {
+    pub expected: NixType,
+    pub got: NixType,
+}
+
+pub trait SlotContent<'gc> {
+    type Ty: Into<Value<'gc>> + TryFrom<Value<'gc>> + 'gc;
+}
+
+impl<'gc> SlotContent<'gc> for Value<'gc> {
+    type Ty = Value<'gc>;
+}
+
+impl<'gc> SlotContent<'gc> for StrictValue<'gc> {
+    type Ty = StrictValue<'gc>;
+}
+
+impl<'gc, T> SlotContent<'gc> for T
+where
+    T: ValueVariant<'gc>,
+{
+    type Ty = T::Ty;
+}
+
+pub struct Slot<T> {
+    depth: u8,
+    _marker: PhantomData<T>,
+}
+
+impl<T> Slot<T> {
+    #[inline(always)]
+    pub const fn new(depth: u8) -> Self {
+        Self {
+            depth,
+            _marker: PhantomData,
+        }
+    }
+}
+
+impl<'gc, T> Slot<T>
+where
+    T: SlotContent<'gc>,
+    <T::Ty as TryFrom<Value<'gc>>>::Error: std::fmt::Debug,
+{
+    #[inline(always)]
+    pub fn read<M: Machine<'gc>>(&self, m: &M) -> T::Ty {
+        T::Ty::try_from(m.peek(self.depth as usize)).expect("slot held a value of the wrong type")
+    }
+
+    #[inline(always)]
+    pub fn write<M: Machine<'gc>>(&self, m: &mut M, val: T::Ty) {
+        m.replace(self.depth as usize, T::Ty::into(val));
+    }
+}
+
+impl<'gc> Slot<Value<'gc>> {
+    #[inline(always)]
+    pub fn force<T: Forced<'gc>, M: Machine<'gc>>(
+        &self,
+        m: &mut M,
+        reader: &mut BytecodeReader<'_>,
+        mc: &Mutation<'gc>,
+    ) -> ControlFlow<Break, Slot<T>> {
+        T::force_and_check(m, reader, mc, self.depth as usize, reader.inst_start_pc())?;
+        ControlFlow::Continue(Slot::new(self.depth))
+    }
+
+    #[inline(always)]
+    pub fn force_to_pc<M: Machine<'gc>>(
+        &self,
+        m: &mut M,
+        reader: &mut BytecodeReader<'_>,
+        mc: &Mutation<'gc>,
+        pc: usize,
+    ) -> Step {
+        m.force_slot_to_pc(self.depth as usize, reader, mc, pc)
+    }
+}

fix-runtime/src/state.rs

@@ -1,14 +1,13 @@
 use std::ops::ControlFlow;
 use std::path::PathBuf;
 
-use fix_common::StringId;
 use fix_error::Error;
+use fix_lang::StringId;
 use gc_arena::{Collect, Gc};
 use hashbrown::HashSet;
 
-use crate::{GcEnv, StaticValue, Thunk};
+use crate::{GcEnv, Thunk};
 
-#[allow(dead_code)]
 pub enum VmError {
     Catchable(String),
     Uncatchable(Box<Error>),
@@ -51,7 +50,6 @@ pub enum Break {
 
 pub type Step = ControlFlow<Break>;
 
-#[allow(dead_code)]
 pub struct ErrorFrame {
     pub span_id: u32,
     pub message: Option<String>,
@@ -61,8 +59,9 @@ pub struct ErrorFrame {
 #[collect(no_drop)]
 pub struct CallFrame<'gc> {
     pub pc: usize,
-    pub thunk: Option<Gc<'gc, Thunk<'gc>>>,
     pub env: GcEnv<'gc>,
+    pub thunk: Option<Gc<'gc, Thunk<'gc>>>,
+    pub depth: Option<usize>,
 }
 
 #[derive(Debug)]
@@ -87,13 +86,3 @@ pub enum ExtraScope {
         slot_id: u32,
     },
 }
-
-pub enum OperandData {
-    Const(StaticValue),
-    BigInt(i64),
-    Local { layer: u8, idx: u32 },
-    BuiltinConst(StringId),
-    Builtins,
-    ReplBinding(StringId),
-    ScopedImportBinding { slot_id: u32, name: StringId },
-}

fix-runtime/src/string_context.rs

@@ -31,10 +31,10 @@ impl StringContextElem {
                 drv_path: drv_path.into(),
             }
         } else if let Some(rest) = encoded.strip_prefix('!') {
-            if let Some(second_bang) = rest.find('!') {
+            if let Some((output, drv_path)) = rest.split_once('!') {
                 Self::Built {
-                    output: rest[..second_bang].into(),
-                    drv_path: rest[second_bang + 1..].into(),
+                    output: output.into(),
+                    drv_path: drv_path.into(),
                 }
             } else {
                 Self::Opaque {
@@ -89,7 +89,7 @@ impl<'a> IntoIterator for &'a mut StringContext {
 impl FromIterator<StringContextElem> for StringContext {
     fn from_iter<T: IntoIterator<Item = StringContextElem>>(iter: T) -> Self {
         Self {
-            data: iter.into_iter().collect()
+            data: iter.into_iter().collect(),
         }
     }
 }
@@ -117,6 +117,10 @@ impl StringContext {
         }
     }
 
+    #[expect(
+        clippy::indexing_slicing,
+        reason = "`i`/`j` stay strictly below their lengths inside the loop, and the trailing slices use those in-bounds cursors as start indices"
+    )]
     pub fn merge(&self, other: &Self) -> Self {
         if self.data.is_empty() {
             return other.clone();

fix-runtime/src/value.rs

@@ -1,17 +1,15 @@
-#![allow(dead_code)]
-
 use std::cell::RefCell;
 use std::fmt;
 use std::marker::PhantomData;
 use std::mem::size_of;
 use std::ops::Deref;
 
-use fix_builtins::BuiltinId;
-use fix_common::*;
+use fix_bytecode::Continuation;
+use fix_lang::*;
+use fix_macros::unelide_lifetimes;
 use gc_arena::barrier::Unlock;
 use gc_arena::collect::Trace;
 use gc_arena::{Collect, Gc, GcRefLock, Mutation, RefLock};
-use num_enum::TryFromPrimitive;
 use smallvec::SmallVec;
 use string_interner::Symbol;
 use string_interner::symbol::SymbolU32;
@@ -23,37 +21,99 @@ mod private {
     pub trait Cealed {}
 }
 
-/// # Safety
-///
-/// TAG must be unique among all implementors.
-#[allow(private_interfaces)]
-pub unsafe trait Storable: private::Cealed {
-    const TAG: RawTag;
+pub trait ValueVariant<'gc>: private::Cealed {
+    #[expect(
+        private_bounds,
+        reason = "Storable is a sealed implementation detail of the value system"
+    )]
+    type Ty: Storable<'gc>;
+    const TYPE: NixType;
+}
+
+trait Storable<'gc>: TryFrom<Value<'gc>> + Into<Value<'gc>> + private::Cealed + 'gc {
+    fn is(raw: &RawBox) -> bool;
+
+    fn to_raw_box(self) -> RawBox;
+    /// # Safety
+    ///
+    /// `raw` must represent a valid `Self`.
+    unsafe fn from_raw_box(raw: RawBox) -> Self;
 }
-#[allow(private_bounds)]
-pub trait InlineStorable: Storable + RawStore {}
-pub trait GcStorable: Storable {}
 
 macro_rules! define_value_types {
     (
-        inline { $($itype:ty => $itag:expr, $iname:literal;)* }
-        gc { $($gtype:ty => $gtag:expr, $gname:literal;)* }
+        inline { $($itype:ty => $itag:path, $ity:path, $iname:literal;)* }
+        gc { $($gtype:ty => $gtag:path, $gty:path, $gname:literal;)* }
     ) => {
         $(
-        #[allow(private_interfaces)]
-        unsafe impl Storable for $itype {
-            const TAG: RawTag = $itag;
+        impl Storable<'_> for $itype {
+            #[inline(always)]
+            fn is(value: &RawBox) -> bool {
+                value.tag() == Some($itag)
+            }
+            #[inline(always)]
+            fn to_raw_box(self) -> RawBox {
+                RawBox::from_value(RawValue::store($itag, self))
+            }
+            #[inline(always)]
+            unsafe fn from_raw_box(raw: RawBox) -> Self {
+                // SAFETY: the caller guarantees `raw` represents a valid
+                // `Self` of this inline type, so it holds a `Value` (making
+                // `value()` `Some`) whose payload decodes to this type.
+                unsafe { <Self as RawStore>::from_val(raw.value().unwrap_unchecked()) }
+            }
         }
-        impl InlineStorable for $itype {}
         impl private::Cealed for $itype {}
+        impl<'gc> ValueVariant<'gc> for $itype {
+            type Ty = $itype;
+            const TYPE: NixType = $ity;
+        }
+        impl<'gc> TryFrom<Value<'gc>> for $itype {
+            type Error = ();
+            fn try_from(val: Value<'gc>) -> Result<Self, Self::Error> {
+                <Self as Storable>::is(&val.raw)
+                    // SAFETY: `is` returned true, so `val.raw` represents a
+                    // valid `Self` of this GC type.
+                    .then(|| unsafe { <Self as Storable>::from_raw_box(val.raw) })
+                    .ok_or(())
+            }
+        }
         )*
         $(
-        #[allow(private_interfaces)]
-        unsafe impl Storable for $gtype {
-            const TAG: RawTag = $gtag;
+        impl<'gc> Storable<'gc> for Gc<'gc, unelide_lifetimes!('gc; $gtype)> {
+            #[inline(always)]
+            fn is(value: &RawBox) -> bool {
+                value.tag() == Some($gtag)
             }
-        impl GcStorable for $gtype {}
+            #[inline(always)]
+            fn to_raw_box(self) -> RawBox {
+                RawBox::from_value(RawValue::store($gtag, Gc::as_ptr(self)))
+            }
+            #[inline(always)]
+            unsafe fn from_raw_box(raw: RawBox) -> Self {
+                // SAFETY: the caller guarantees `raw` represents a valid
+                // `Self` of this GC type, so it holds a `Value` (making
+                // `value()` `Some`) whose payload is the pointer originally
+                // produced by `Gc::as_ptr` in `to_raw_box`.
+                unsafe { Gc::from_ptr(<*mut $gtype as RawStore>::from_val(raw.value().unwrap_unchecked())) }
+            }
+        }
+        impl<'gc> TryFrom<Value<'gc>> for Gc<'gc, unelide_lifetimes!('gc; $gtype)> {
+            type Error = ();
+            fn try_from(val: Value<'gc>) -> Result<Self, Self::Error> {
+                <Self as Storable>::is(&val.raw)
+                    // SAFETY: `is` returned true, so `val.raw` represents a
+                    // valid `Self` of this GC type.
+                    .then(|| unsafe { <Self as Storable>::from_raw_box(val.raw) })
+                    .ok_or(())
+            }
+        }
+        impl private::Cealed for Gc<'_, $gtype> {}
         impl private::Cealed for $gtype {}
+        impl<'gc> ValueVariant<'gc> for unelide_lifetimes!('gc; $gtype) {
+            type Ty = Gc<'gc, unelide_lifetimes!('gc; $gtype)>;
+            const TYPE: NixType = $gty;
+        }
         )*
 
         const _: () = assert!(size_of::<Value<'static>>() == 8);
@@ -65,6 +125,7 @@ macro_rules! define_value_types {
             let mut mask_true: u8 = 0;
             let mut i = 0;
             while i < tags.len() {
+                #[expect(clippy::indexing_slicing, reason = "loop condition guarantees `i < tags.len()`")]
                 let (neg, val) = tags[i];
                 let bit = 1 << val;
                 if neg {
@@ -78,15 +139,20 @@ macro_rules! define_value_types {
             }
         };
 
+        // SAFETY: `trace` visits every reachable `Gc` pointer: for each GC
+        // tag it downcasts to the concrete `Gc` type and forwards `trace`,
+        // while inline tags hold no GC pointers and need no tracing.
         unsafe impl<'gc> Collect<'gc> for Value<'gc> {
             const NEEDS_TRACE: bool = true;
             fn trace<T: Trace<'gc>>(&self, cc: &mut T) {
                 let Some(tag) = self.raw.tag() else { return };
                 match tag {
-                    $(<$gtype as Storable>::TAG => unsafe {
-                        self.load_gc::<$gtype>().trace(cc)
+                    $($gtag => unsafe {
+                        // SAFETY: `tag` matched `$gtag`, so `downcast` to the
+                        // corresponding GC type is guaranteed to be `Some`.
+                        self.downcast::<$gtype>().unwrap_unchecked().trace(cc)
                     },)*
-                    $(<$itype as Storable>::TAG => (),)*
+                    $($itag => (),)*
                     _ => unreachable!("invalid value tag"),
                 }
             }
@@ -95,13 +161,17 @@ macro_rules! define_value_types {
         impl fmt::Debug for Value<'_> {
             fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
                 match self.tag() {
+                    // SAFETY: `tag()` is `None`, meaning the `RawBox` holds a
+                    // float, so `float()` is guaranteed to be `Some`.
                     None => write!(f, "Float({:?})", unsafe {
                         self.raw.float().unwrap_unchecked()
                     }),
-                    $(Some(<$itype as Storable>::TAG) => write!(f, "{}({:?})", $iname, unsafe {
-                        self.as_inline::<$itype>().unwrap_unchecked()
+                    // SAFETY: `tag()` matched `$itag`, so `downcast` to the
+                    // corresponding inline type is guaranteed to be `Some`.
+                    $(Some($itag) => write!(f, "{}({:?})", $iname, unsafe {
+                        self.downcast::<$itype>().unwrap_unchecked()
                     }),)*
-                    $(Some(<$gtype as Storable>::TAG) =>
+                    $(Some($gtag) =>
                         write!(f, "{}(..)", $gname),)*
                     _ => unreachable!("invalid value tag"),
                 }
@@ -112,21 +182,58 @@ macro_rules! define_value_types {
 
 define_value_types! {
     inline {
-        i32 => RawTag::P1, "SmallInt";
-        bool => RawTag::P2, "Bool";
-        Null => RawTag::P3, "Null";
-        StringId => RawTag::P4, "SmallString";
-        PrimOp => RawTag::P5, "PrimOp";
-        Path => RawTag::N6, "Path";
+        i32 => RawTag::P1, NixType::Int, "SmallInt";
+        bool => RawTag::P2, NixType::Bool, "Bool";
+        Null => RawTag::P3, NixType::Null, "Null";
+        StringId => RawTag::P4, NixType::String, "SmallString";
+        PrimOp => RawTag::P5, NixType::PrimOp, "PrimOp";
+        Path => RawTag::P6, NixType::Path, "Path";
     }
     gc {
-        i64 => RawTag::P6, "BigInt";
-        NixString => RawTag::P7, "String";
-        AttrSet<'_> => RawTag::N1, "AttrSet";
-        List<'_> => RawTag::N2, "List";
-        Thunk<'_> => RawTag::N3, "Thunk";
-        Closure<'_> => RawTag::N4, "Closure";
-        PrimOpApp<'_> => RawTag::N5, "PrimOpApp";
+        i64 => RawTag::P7, NixType::Int, "BigInt";
+        NixString => RawTag::N1, NixType::String, "String";
+        AttrSet<'_> => RawTag::N2, NixType::AttrSet, "AttrSet";
+        List<'_> => RawTag::N3, NixType::List, "List";
+        Thunk<'_> => RawTag::N4, NixType::Thunk, "Thunk";
+        Closure<'_> => RawTag::N5, NixType::Closure, "Closure";
+        PrimOpApp<'_> => RawTag::N6, NixType::PrimOpApp, "PrimOpApp";
+    }
+}
+
+impl private::Cealed for f64 {}
+
+impl Storable<'_> for f64 {
+    #[inline(always)]
+    fn is(value: &RawBox) -> bool {
+        value.is_float()
+    }
+    #[inline(always)]
+    fn to_raw_box(self) -> RawBox {
+        RawBox::from_float(self)
+    }
+    #[inline(always)]
+    unsafe fn from_raw_box(raw: RawBox) -> Self {
+        // SAFETY: the caller guarantees `raw` represents a valid `f64`, so
+        // `float()` is guaranteed to be `Some`.
+        unsafe { raw.float().copied().unwrap_unchecked() }
+    }
+}
+
+impl<'gc> ValueVariant<'gc> for f64 {
+    type Ty = f64;
+    const TYPE: NixType = NixType::Float;
+}
+
+impl<'gc> TryFrom<Value<'gc>> for f64 {
+    type Error = ();
+    fn try_from(value: Value<'gc>) -> Result<Self, Self::Error> {
+        value.downcast::<f64>().ok_or(())
+    }
+}
+
+impl<'gc, T: Storable<'gc>> From<T> for Value<'gc> {
+    fn from(value: T) -> Self {
+        Value::new(value)
     }
 }
 
@@ -143,33 +250,11 @@ pub struct Value<'gc> {
 impl Default for Value<'_> {
     #[inline(always)]
     fn default() -> Self {
-        Self::new_inline(Null)
+        Self::new(Null)
     }
 }
 
 impl<'gc> Value<'gc> {
-    #[inline(always)]
-    fn from_raw_value(rv: RawValue) -> Self {
-        Self {
-            raw: RawBox::from_value(rv),
-            _marker: PhantomData,
-        }
-    }
-
-    /// Load a GC pointer from a value with a negative tag.
-    ///
-    /// # Safety
-    ///
-    /// The value must actually store a `Gc<'gc, T>` with the matching type.
-    #[inline(always)]
-    unsafe fn load_gc<T: GcStorable>(self) -> Gc<'gc, T> {
-        unsafe {
-            let rv = self.raw.value().unwrap_unchecked();
-            let ptr: *const T = <*const T as RawStore>::from_val(rv);
-            Gc::from_ptr(ptr)
-        }
-    }
-
     #[inline(always)]
     const fn tag(self) -> Option<RawTag> {
         self.raw.tag()
@@ -178,75 +263,37 @@ impl<'gc> Value<'gc> {
 
 impl<'gc> Value<'gc> {
     #[inline]
-    pub fn new_float(val: f64) -> Self {
+    #[expect(
+        private_bounds,
+        reason = "Storable is a sealed implementation detail of the value system"
+    )]
+    pub fn new<T: Storable<'gc>>(val: T) -> Self {
         Self {
-            raw: RawBox::from_float(val),
+            raw: val.to_raw_box(),
             _marker: PhantomData,
         }
     }
 
-    #[inline]
-    pub fn new_inline<T: InlineStorable>(val: T) -> Self {
-        Self::from_raw_value(RawValue::store(T::TAG, val))
-    }
-
-    #[inline]
-    pub fn new_gc<T: GcStorable>(gc: Gc<'gc, T>) -> Self {
-        let ptr = Gc::as_ptr(gc);
-        Self::from_raw_value(RawValue::store(T::TAG, ptr))
-    }
-
     #[inline]
     pub fn make_int(val: i64, mc: &Mutation<'gc>) -> Self {
         if val >= i32::MIN as i64 && val <= i32::MAX as i64 {
-            Value::new_inline(val as i32)
+            Value::new(val as i32)
         } else {
-            Value::new_gc(Gc::new(mc, val))
-        }
-    }
-}
-
-impl<'gc> Value<'gc> {
-    #[inline]
-    pub fn is_float(self) -> bool {
-        self.raw.is_float()
-    }
-
-    #[inline]
-    pub fn is<T: Storable>(self) -> bool {
-        self.tag() == Some(T::TAG)
-    }
-}
-
-impl<'gc> Value<'gc> {
-    #[inline]
-    pub fn as_float(self) -> Option<f64> {
-        self.raw.float().copied()
-    }
-
-    #[inline]
-    pub fn as_inline<T: InlineStorable>(self) -> Option<T> {
-        if self.is::<T>() {
-            Some(unsafe {
-                let rv = self.raw.value().unwrap_unchecked();
-                T::from_val(rv)
-            })
-        } else {
-            None
+            Value::new(Gc::new(mc, val))
         }
     }
 
     #[inline]
-    pub fn as_gc<T: GcStorable>(self) -> Option<Gc<'gc, T>> {
-        if self.is::<T>() {
-            Some(unsafe {
-                let rv = self.raw.value().unwrap_unchecked();
-                let ptr: *const T = <*const T as RawStore>::from_val(rv);
-                Gc::from_ptr(ptr)
-            })
-        } else {
-            None
+    pub fn is<T: ValueVariant<'gc>>(self) -> bool {
+        T::Ty::is(&self.raw)
     }
+
+    #[inline]
+    pub fn downcast<T: ValueVariant<'gc>>(self) -> Option<T::Ty> {
+        self.is::<T>()
+            // SAFETY: `is::<T>()` returned true, so `self.raw` represents a
+            // valid `T::Ty`.
+            .then(|| unsafe { T::Ty::from_raw_box(self.raw) })
     }
 
     #[inline]
@@ -255,19 +302,19 @@ impl<'gc> Value<'gc> {
     }
 
     #[inline]
-    pub fn as_num(self) -> Option<NixNum> {
-        if let Some(i) = self.as_inline::<i32>() {
+    pub fn downcast_num(self) -> Option<NixNum> {
+        if let Some(i) = self.downcast::<i32>() {
             Some(NixNum::Int(i as i64))
-        } else if let Some(gc_i) = self.as_gc::<i64>() {
+        } else if let Some(gc_i) = self.downcast::<i64>() {
             Some(NixNum::Int(*gc_i))
         } else {
-            self.as_float().map(NixNum::Float)
+            self.downcast::<f64>().map(NixNum::Float)
         }
     }
 
     #[inline]
     pub fn restrict(self) -> Result<StrictValue<'gc>, Gc<'gc, Thunk<'gc>>> {
-        if let Some(thunk) = self.as_gc::<Thunk<'gc>>() {
+        if let Some(thunk) = self.downcast::<Thunk>() {
             Err(thunk)
         } else {
             Ok(StrictValue(self))
@@ -275,8 +322,12 @@ impl<'gc> Value<'gc> {
     }
 
     #[inline]
+    #[expect(
+        clippy::unreachable,
+        reason = "the preceding `if`/`else if` chain exhausts every registered value tag"
+    )]
     pub fn ty(self) -> NixType {
-        if self.is_float() {
+        if self.is::<f64>() {
             NixType::Float
         } else if self.is::<i32>() || self.is::<i64>() {
             NixType::Int
@@ -308,28 +359,13 @@ impl<'gc> Value<'gc> {
     }
 
     #[inline]
-    pub fn expect_inline<T: InlineStorable>(self) -> Result<T, NixType> {
-        self.as_inline::<T>().ok_or_else(|| self.ty())
-    }
-
-    #[inline]
-    pub fn expect_gc<T: GcStorable>(self) -> Result<Gc<'gc, T>, NixType> {
-        self.as_gc::<T>().ok_or_else(|| self.ty())
+    pub fn expect<T: ValueVariant<'gc>>(self) -> Result<T::Ty, NixType> {
+        self.downcast::<T>().ok_or_else(|| self.ty())
     }
 
     #[inline]
     pub fn expect_num(self) -> Result<NixNum, NixType> {
-        self.as_num().ok_or_else(|| self.ty())
-    }
-
-    #[inline]
-    pub fn expect_bool(self) -> Result<bool, NixType> {
-        self.as_inline::<bool>().ok_or_else(|| self.ty())
-    }
-
-    #[inline]
-    pub fn expect_float(self) -> Result<f64, NixType> {
-        self.as_float().ok_or_else(|| self.ty())
+        self.downcast_num().ok_or_else(|| self.ty())
     }
 }
 
@@ -347,37 +383,24 @@ impl<'gc> From<StaticValue> for Value<'gc> {
 
 impl StaticValue {
     #[inline]
-    pub fn new_float(val: f64) -> Self {
-        Self(Value::new_float(val))
+    #[expect(
+        private_bounds,
+        reason = "Storable is a sealed implementation detail of the value system"
+    )]
+    pub fn new<T: Storable<'static>>(val: T) -> Self {
+        Self(Value::new(val))
     }
+
     #[inline]
-    pub fn new_inline<T: InlineStorable>(val: T) -> Self {
-        Self(Value::new_inline(val))
-    }
-    #[inline]
-    pub fn new_primop(id: BuiltinId, arity: u8, dispatch_ip: u32) -> Self {
-        Self(Value::new_inline(PrimOp {
-            id,
-            arity,
-            dispatch_ip,
-        }))
-    }
-    #[inline]
-    pub fn is_float(self) -> bool {
-        self.0.is_float()
-    }
-    #[inline]
-    pub fn is<T: InlineStorable>(self) -> bool {
+    pub fn is<T: ValueVariant<'static>>(self) -> bool {
         self.0.is::<T>()
     }
+
     #[inline]
-    pub fn as_float(self) -> Option<f64> {
-        self.0.as_float()
-    }
-    #[inline]
-    pub fn as_inline<T: InlineStorable>(self) -> Option<T> {
-        self.0.as_inline::<T>()
+    pub fn downcast<T: ValueVariant<'static>>(self) -> Option<T::Ty> {
+        self.0.downcast::<T>()
     }
+
     #[inline]
     pub fn to_bits(self) -> u64 {
         self.0.raw.to_bits()
@@ -476,6 +499,10 @@ impl<'gc> AttrSet<'gc> {
         Self { entries }
     }
 
+    #[expect(
+        clippy::indexing_slicing,
+        reason = "index comes from a successful `binary_search_by_key`, so it is a valid entry index"
+    )]
     pub fn lookup(&self, key: StringId) -> Option<Value<'gc>> {
         self.entries
             .binary_search_by_key(&key, |(k, _)| *k)
@@ -487,6 +514,10 @@ impl<'gc> AttrSet<'gc> {
         self.entries.binary_search_by_key(&key, |(k, _)| *k).is_ok()
     }
 
+    #[expect(
+        clippy::indexing_slicing,
+        reason = "`i`/`j` stay strictly below their lengths inside the loop, and the trailing slices use those in-bounds cursors as start indices"
+    )]
     pub fn merge(&self, other: &Self, mc: &Mutation<'gc>) -> Gc<'gc, Self> {
         use std::cmp::Ordering::*;
 
@@ -547,6 +578,9 @@ impl<'gc> List<'gc> {
 impl<'gc> Unlock for List<'gc> {
     type Unlocked = RefCell<SmallVec<[Value<'gc>; 4]>>;
     unsafe fn unlock_unchecked(&self) -> &Self::Unlocked {
+        // SAFETY: the caller upholds the `Unlock` contract (mutation happens
+        // behind a write barrier); we forward that obligation to the inner
+        // `RefLock`'s `unlock_unchecked`.
         unsafe { self.inner.unlock_unchecked() }
     }
 }
@@ -570,14 +604,6 @@ pub struct Env<'gc> {
 }
 pub type GcEnv<'gc> = GcRefLock<'gc, Env<'gc>>;
 
-#[derive(Collect, Debug)]
-#[collect(no_drop)]
-pub struct WithEnv<'gc> {
-    pub env: Value<'gc>,
-    pub prev: Option<GcWithEnv<'gc>>,
-}
-pub type GcWithEnv<'gc> = Gc<'gc, WithEnv<'gc>>;
-
 impl<'gc> Env<'gc> {
     pub fn empty() -> Self {
         Env {
@@ -586,6 +612,10 @@ impl<'gc> Env<'gc> {
         }
     }
 
+    #[expect(
+        clippy::indexing_slicing,
+        reason = "`locals` was just created with `1 + n_locals` elements, so index 0 is always valid"
+    )]
     pub fn with_arg(arg: Value<'gc>, n_locals: u32, prev: Gc<'gc, RefLock<Env<'gc>>>) -> Self {
         let mut locals = smallvec::smallvec![Value::default(); 1 + n_locals as usize];
         locals[0] = arg;
@@ -623,6 +653,18 @@ pub struct PrimOp {
     pub dispatch_ip: u32,
 }
 
+impl From<BuiltinId> for PrimOp {
+    fn from(id: BuiltinId) -> Self {
+        let BuiltinInfo { arity, .. } = id.info();
+        let dispatch_ip = Continuation::entry_for_builtin(id).ip();
+        Self {
+            id,
+            arity,
+            dispatch_ip,
+        }
+    }
+}
+
 impl RawStore for PrimOp {
     fn to_val(self, value: &mut RawValue) {
         let bytes = self.dispatch_ip.to_le_bytes();
@@ -638,7 +680,7 @@ impl RawStore for PrimOp {
     fn from_val(value: &RawValue) -> Self {
         let [id, arity, bytes @ ..] = *value.data();
         Self {
-            id: BuiltinId::try_from_primitive(id).expect("invalid BuiltinId"),
+            id: BuiltinId::try_from(id).expect("invalid BuiltinId"),
             arity,
             dispatch_ip: u32::from_le_bytes(bytes),
         }
@@ -673,6 +715,19 @@ impl<'gc> Deref for StrictValue<'gc> {
     }
 }
 
+impl<'gc> From<StrictValue<'gc>> for Value<'gc> {
+    fn from(value: StrictValue<'gc>) -> Self {
+        value.0
+    }
+}
+
+impl<'gc> TryFrom<Value<'gc>> for StrictValue<'gc> {
+    type Error = Gc<'gc, Thunk<'gc>>;
+    fn try_from(value: Value<'gc>) -> Result<Self, Self::Error> {
+        value.restrict()
+    }
+}
+
 impl fmt::Debug for StrictValue<'_> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         fmt::Debug::fmt(&self.0, f)

fix-vm/Cargo.toml

@@ -3,22 +3,20 @@ name = "fix-vm"
 version = "0.1.0"
 edition = "2024"
 
-[features]
-tailcall = []
-
 [dependencies]
 gc-arena = { workspace = true }
 hashbrown = { workspace = true }
-num_enum = { workspace = true }
 smallvec = { workspace = true }
-string-interner = { workspace = true }
-likely_stable = { workspace = true }
-sptr = "0.3"
-sysinfo = { version = "0.38", default-features = false, features = ["system"] }
+sysinfo = { version = "0.39", default-features = false, features = ["system"] }
 
-fix-builtins = { path = "../fix-builtins" }
-fix-codegen = { path = "../fix-codegen" }
-fix-common = { path = "../fix-common" }
+fix-bytecode = { path = "../fix-bytecode" }
 fix-error = { path = "../fix-error" }
-fix-abstract-vm = { path = "../fix-abstract-vm" }
-fix-primops = { path = "../fix-primops" }
+fix-lang = { path = "../fix-lang" }
+fix-macros = { path = "../fix-macros" }
+fix-runtime = { path = "../fix-runtime" }
+
+[features]
+tailcall = []
+
+[lints]
+workspace = true

fix-vm/src/dispatch_tailcall.rs

@@ -22,6 +22,7 @@ pub(crate) type OpFn<'gc, C> = extern "rust-preserve-none" fn(
 
 pub(crate) struct DispatchTable<'gc, C: VmRuntimeCtx>(pub(crate) [OpFn<'gc, C>; 256]);
 
+#[expect(clippy::panic, reason = "illegal opcode should panic")]
 extern "rust-preserve-none" fn op_illegal<'gc, C: VmRuntimeCtx>(
     _vm: &mut Vm<'gc>,
     _mc: &Mutation<'gc>,
@@ -61,7 +62,7 @@ macro_rules! tail_fn {
             pc: u32,
             fuel: u32,
         ) -> TailResult {
-            let result = vm.$name();
+            let result = crate::instructions::$name(vm);
             tail_dispatch_after!(result, pc + 1, vm, mc, ctx, bc, table, fuel)
         }
     };
@@ -76,7 +77,7 @@ macro_rules! tail_fn {
             fuel: u32,
         ) -> TailResult {
             let mut reader = BytecodeReader::from_after_op(bc, pc as usize);
-            let result = vm.$name(&mut reader);
+            let result = crate::instructions::$name(vm, &mut reader);
             tail_dispatch_after!(result, reader.pc() as u32, vm, mc, ctx, bc, table, fuel)
         }
     };
@@ -91,7 +92,7 @@ macro_rules! tail_fn {
             fuel: u32,
         ) -> TailResult {
             let mut reader = BytecodeReader::from_after_op(bc, pc as usize);
-            let result = vm.$name(&mut reader, mc);
+            let result = crate::instructions::$name(vm, &mut reader, mc);
             tail_dispatch_after!(result, reader.pc() as u32, vm, mc, ctx, bc, table, fuel)
         }
     };
@@ -106,7 +107,7 @@ macro_rules! tail_fn {
             fuel: u32,
         ) -> TailResult {
             let mut reader = BytecodeReader::from_after_op(bc, pc as usize);
-            let result = vm.$name(ctx, &mut reader, mc);
+            let result = crate::instructions::$name(vm, ctx, &mut reader, mc);
             tail_dispatch_after!(result, reader.pc() as u32, vm, mc, ctx, bc, table, fuel)
         }
     };
@@ -120,7 +121,7 @@ macro_rules! tail_fn {
             pc: u32,
             fuel: u32,
         ) -> TailResult {
-            let result = vm.$name(ctx);
+            let result = crate::instructions::$name(vm, ctx);
             tail_dispatch_after!(result, pc + 1, vm, mc, ctx, bc, table, fuel)
         }
     };
@@ -144,7 +145,7 @@ tail_fn!(op_make_closure, (reader, mc));
 tail_fn!(op_make_pattern_closure, (reader, mc));
 
 tail_fn!(op_call, (ctx, reader, mc));
-tail_fn!(op_dispatch_primop, (ctx, reader, mc));
+tail_fn!(op_dispatch_cont, (ctx, reader, mc));
 tail_fn!(op_return, (ctx, reader, mc));
 
 tail_fn!(op_make_attrs, (ctx, reader, mc));
@@ -200,18 +201,18 @@ tail_fn!(op_load_scoped_binding, (ctx, reader, mc));
 macro_rules! table {
     ($($variant:ident => $fn:ident),* $(,)?) => {
         impl<'gc, C: VmRuntimeCtx> DispatchTable<'gc, C> {
+            #[expect(clippy::indexing_slicing, reason = "Op is repr(u8)")]
             pub(crate) const NEW: Self = {
                 let mut arr: [OpFn<'gc, C>; 256] = [op_illegal; 256];
-                $( arr[fix_codegen::Op::$variant as usize] = $fn; )*
+                $( arr[fix_bytecode::Op::$variant as usize] = $fn; )*
                 DispatchTable(arr)
             };
         }
 
-        // Exhaustiveness check: fails to compile if `fix_codegen::Op` gains,
+        // Exhaustiveness check: fails to compile if `fix_bytecode::Op` gains,
         // loses, or renames a variant that isn't wired up above.
-        #[allow(dead_code)]
-        const _: fn(fix_codegen::Op) = |op| match op {
-            $( fix_codegen::Op::$variant => (), )*
+        const _: fn(fix_bytecode::Op) = |op| match op {
+            $( fix_bytecode::Op::$variant => (), )*
         };
     };
 }
@@ -235,7 +236,7 @@ table! {
     MakePatternClosure    => op_make_pattern_closure,
 
     Call                  => op_call,
-    DispatchPrimOp        => op_dispatch_primop,
+    DispatchCont          => op_dispatch_cont,
     Return                => op_return,
 
     MakeAttrs             => op_make_attrs,
@@ -291,6 +292,10 @@ table! {
     Illegal               => op_illegal,
 }
 
+#[expect(
+    clippy::indexing_slicing,
+    reason = "assume well-formed bytecode; Op is repr(u8)"
+)]
 pub(crate) fn run_tailcall<'gc, C: VmRuntimeCtx>(
     vm: &mut Vm<'gc>,
     mc: &Mutation<'gc>,

fix-vm/src/instructions/arithmetic.rs

@@ -1,19 +1,18 @@
 use std::cmp::Ordering;
 
-use fix_abstract_vm::*;
+use fix_runtime::*;
 use gc_arena::{Gc, Mutation, RefLock};
 
 use crate::{BytecodeReader, NixNum, Step, VmError, VmRuntimeCtx};
 
-impl<'gc> crate::Vm<'gc> {
-    #[inline(always)]
-    pub(crate) fn op_add(
-        &mut self,
+#[inline(always)]
+pub(crate) fn op_add<'gc, M: Machine<'gc>>(
+    m: &mut M,
     ctx: &mut impl VmRuntimeCtx,
     reader: &mut BytecodeReader<'_>,
     mc: &Mutation<'gc>,
-    ) -> Step {
-        let (lhs, rhs) = self.force_and_retry::<(StrictValue, StrictValue)>(reader, mc)?;
+) -> Step {
+    let (lhs, rhs) = m.force_and_retry::<(StrictValue, StrictValue)>(reader, mc)?;
     // if the LHS is a path, the result is a path obtained by
     // canonicalizing the concatenated string. RHS may be a path or a
     // string. (A `string + path` keeps the string-typed result, handled
@@ -21,7 +20,7 @@ impl<'gc> crate::Vm<'gc> {
     if lhs.is::<Path>() {
         let (Some(ls), Some(rs)) = (ctx.get_string_or_path(lhs), ctx.get_string_or_path(rhs))
         else {
-                return self.finish_err(fix_error::Error::eval_error(format!(
+            return m.finish_err(fix_error::Error::eval_error(format!(
                 "cannot append {} to a path",
                 rhs.ty()
             )));
@@ -29,7 +28,7 @@ impl<'gc> crate::Vm<'gc> {
         let combined = format!("{ls}{rs}");
         let canon = canon_path_str(&combined);
         let sid = ctx.intern_string(canon);
-            self.push(Value::new_inline(fix_abstract_vm::Path(sid)));
+        m.push(Value::new(fix_runtime::Path(sid)));
         return Step::Continue(());
     }
     if let (Some(ls), Some(rs)) = (ctx.get_string(lhs), ctx.get_string_or_path(rhs)) {
@@ -40,54 +39,66 @@ impl<'gc> crate::Vm<'gc> {
             mc,
             crate::NixString::with_context(format!("{ls}{rs}"), merged),
         );
-            self.push(Value::new_gc(ns));
+        m.push(Value::new(ns));
         return Step::Continue(());
     }
     let res = numeric_binop(lhs, rhs, mc, i64::wrapping_add, |a, b| a + b);
     match res {
         Ok(val) => {
-                self.push(val);
+            m.push(val);
             Step::Continue(())
         }
-            Err(e) => self.finish_vm_err(e),
-        }
+        Err(e) => m.finish_vm_err(e),
     }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_sub(&mut self, reader: &mut BytecodeReader<'_>, mc: &Mutation<'gc>) -> Step {
-        self.op_arith(reader, mc, i64::wrapping_sub, |a, b| a - b)
-    }
+#[inline(always)]
+pub(crate) fn op_sub<'gc, M: Machine<'gc>>(
+    m: &mut M,
+    reader: &mut BytecodeReader<'_>,
+    mc: &Mutation<'gc>,
+) -> Step {
+    op_arith(m, reader, mc, i64::wrapping_sub, |a, b| a - b)
+}
 
-    #[inline(always)]
-    pub(crate) fn op_mul(&mut self, reader: &mut BytecodeReader<'_>, mc: &Mutation<'gc>) -> Step {
-        self.op_arith(reader, mc, i64::wrapping_mul, |a, b| a * b)
-    }
+#[inline(always)]
+pub(crate) fn op_mul<'gc, M: Machine<'gc>>(
+    m: &mut M,
+    reader: &mut BytecodeReader<'_>,
+    mc: &Mutation<'gc>,
+) -> Step {
+    op_arith(m, reader, mc, i64::wrapping_mul, |a, b| a * b)
+}
 
-    #[inline(always)]
-    fn op_arith(
-        &mut self,
+#[inline(always)]
+fn op_arith<'gc, M: Machine<'gc>>(
+    m: &mut M,
     reader: &mut BytecodeReader<'_>,
     mc: &Mutation<'gc>,
     int_op: fn(i64, i64) -> i64,
     float_op: fn(f64, f64) -> f64,
-    ) -> Step {
-        let (lhs, rhs) = self.force_and_retry::<(StrictValue, StrictValue)>(reader, mc)?;
+) -> Step {
+    let (lhs, rhs) = m.force_and_retry::<(StrictValue, StrictValue)>(reader, mc)?;
     let res = numeric_binop(lhs, rhs, mc, int_op, float_op);
     match res {
         Ok(val) => {
-                self.push(val);
+            m.push(val);
             Step::Continue(())
         }
-            Err(e) => self.finish_vm_err(e),
-        }
+        Err(e) => m.finish_vm_err(e),
     }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_div(&mut self, reader: &mut BytecodeReader<'_>, mc: &Mutation<'gc>) -> Step {
-        let (lhs, rhs) = self.force_and_retry::<(StrictValue, StrictValue)>(reader, mc)?;
+#[inline(always)]
+pub(crate) fn op_div<'gc, M: Machine<'gc>>(
+    m: &mut M,
+    reader: &mut BytecodeReader<'_>,
+    mc: &Mutation<'gc>,
+) -> Step {
+    let (lhs, rhs) = m.force_and_retry::<(StrictValue, StrictValue)>(reader, mc)?;
     match (get_num(lhs), get_num(rhs)) {
         (_, Some(NixNum::Int(0))) | (_, Some(NixNum::Float(0.))) => {
-                return self.finish_vm_err(VmError::Uncatchable(fix_error::Error::eval_error(
+            return m.finish_vm_err(VmError::Uncatchable(fix_error::Error::eval_error(
                 "division by zero",
             )));
         }
@@ -96,143 +107,151 @@ impl<'gc> crate::Vm<'gc> {
     let res = numeric_binop(lhs, rhs, mc, |a, b| a / b, |a, b| a / b);
     match res {
         Ok(val) => {
-                self.push(val);
+            m.push(val);
             Step::Continue(())
         }
-            Err(e) => self.finish_vm_err(e),
-        }
+        Err(e) => m.finish_vm_err(e),
     }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_eq(
-        &mut self,
+#[inline(always)]
+pub(crate) fn op_eq<'gc, M: Machine<'gc>>(
+    m: &mut M,
     ctx: &mut impl VmRuntimeCtx,
     reader: &mut BytecodeReader<'_>,
     mc: &Mutation<'gc>,
-    ) -> Step {
-        let (lhs, rhs) = self.force_and_retry::<(StrictValue, StrictValue)>(reader, mc)?;
-        fix_primops::start_eq(self, ctx, reader, mc, lhs, rhs, false)
-    }
+) -> Step {
+    let (lhs, rhs) = m.force_and_retry::<(StrictValue, StrictValue)>(reader, mc)?;
+    crate::primops::start_eq(m, ctx, reader, mc, lhs, rhs, false)
+}
 
-    #[inline(always)]
-    pub(crate) fn op_neq(
-        &mut self,
+#[inline(always)]
+pub(crate) fn op_neq<'gc, M: Machine<'gc>>(
+    m: &mut M,
     ctx: &mut impl VmRuntimeCtx,
     reader: &mut BytecodeReader<'_>,
     mc: &Mutation<'gc>,
-    ) -> Step {
-        let (lhs, rhs) = self.force_and_retry::<(StrictValue, StrictValue)>(reader, mc)?;
-        fix_primops::start_eq(self, ctx, reader, mc, lhs, rhs, true)
-    }
+) -> Step {
+    let (lhs, rhs) = m.force_and_retry::<(StrictValue, StrictValue)>(reader, mc)?;
+    crate::primops::start_eq(m, ctx, reader, mc, lhs, rhs, true)
+}
 
-    #[inline(always)]
-    pub(crate) fn op_lt(
-        &mut self,
+#[inline(always)]
+pub(crate) fn op_lt<'gc, M: Machine<'gc>>(
+    m: &mut M,
     ctx: &mut impl VmRuntimeCtx,
     reader: &mut BytecodeReader<'_>,
     mc: &Mutation<'gc>,
-    ) -> Step {
-        self.compare_values(ctx, reader, mc, Ordering::is_lt)
-    }
+) -> Step {
+    compare_values(m, ctx, reader, mc, Ordering::is_lt)
+}
 
-    #[inline(always)]
-    pub(crate) fn op_gt(
-        &mut self,
+#[inline(always)]
+pub(crate) fn op_gt<'gc, M: Machine<'gc>>(
+    m: &mut M,
     ctx: &mut impl VmRuntimeCtx,
     reader: &mut BytecodeReader<'_>,
     mc: &Mutation<'gc>,
-    ) -> Step {
-        self.compare_values(ctx, reader, mc, Ordering::is_gt)
-    }
+) -> Step {
+    compare_values(m, ctx, reader, mc, Ordering::is_gt)
+}
 
-    #[inline(always)]
-    pub(crate) fn op_leq(
-        &mut self,
+#[inline(always)]
+pub(crate) fn op_leq<'gc, M: Machine<'gc>>(
+    m: &mut M,
     ctx: &mut impl VmRuntimeCtx,
     reader: &mut BytecodeReader<'_>,
     mc: &Mutation<'gc>,
-    ) -> Step {
-        self.compare_values(ctx, reader, mc, Ordering::is_le)
-    }
+) -> Step {
+    compare_values(m, ctx, reader, mc, Ordering::is_le)
+}
 
-    #[inline(always)]
-    pub(crate) fn op_geq(
-        &mut self,
+#[inline(always)]
+pub(crate) fn op_geq<'gc, M: Machine<'gc>>(
+    m: &mut M,
     ctx: &mut impl VmRuntimeCtx,
     reader: &mut BytecodeReader<'_>,
     mc: &Mutation<'gc>,
-    ) -> Step {
-        self.compare_values(ctx, reader, mc, Ordering::is_ge)
-    }
+) -> Step {
+    compare_values(m, ctx, reader, mc, Ordering::is_ge)
+}
 
-    fn compare_values(
-        &mut self,
+fn compare_values<'gc, M: Machine<'gc>>(
+    m: &mut M,
     ctx: &impl VmRuntimeCtx,
     reader: &mut BytecodeReader<'_>,
     mc: &Mutation<'gc>,
     pred: fn(Ordering) -> bool,
-    ) -> Step {
-        let (lhs, rhs) = self.force_and_retry::<(StrictValue, StrictValue)>(reader, mc)?;
-        match self.compare_values_inner(ctx, pred, lhs, rhs) {
+) -> Step {
+    let (lhs, rhs) = m.force_and_retry::<(StrictValue, StrictValue)>(reader, mc)?;
+    match compare_values_inner(m, ctx, pred, lhs, rhs) {
         Ok(()) => Step::Continue(()),
-            Err(e) => self.finish_vm_err(e),
-        }
+        Err(e) => m.finish_vm_err(e),
     }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_concat(
-        &mut self,
+#[inline(always)]
+pub(crate) fn op_concat<'gc, M: Machine<'gc>>(
+    m: &mut M,
     reader: &mut BytecodeReader<'_>,
     mc: &Mutation<'gc>,
-    ) -> Step {
-        let (l, r) = self.force_and_retry::<(Gc<List>, Gc<List>)>(reader, mc)?;
+) -> Step {
+    let (l, r) = m.force_and_retry::<(Gc<List>, Gc<List>)>(reader, mc)?;
     let mut items = smallvec::SmallVec::new();
     items.extend_from_slice(&l.inner.borrow());
     items.extend_from_slice(&r.inner.borrow());
-        self.push(Value::new_gc(Gc::new(
+    m.push(Value::new(Gc::new(
         mc,
         crate::List {
             inner: RefLock::new(items),
         },
     )));
     Step::Continue(())
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_update(
-        &mut self,
+#[inline(always)]
+pub(crate) fn op_update<'gc, M: Machine<'gc>>(
+    m: &mut M,
     reader: &mut BytecodeReader<'_>,
     mc: &Mutation<'gc>,
-    ) -> Step {
-        let (l, r) = self.force_and_retry::<(Gc<AttrSet>, Gc<AttrSet>)>(reader, mc)?;
-        self.push(Value::new_gc(l.merge(&r, mc)));
+) -> Step {
+    let (l, r) = m.force_and_retry::<(Gc<AttrSet>, Gc<AttrSet>)>(reader, mc)?;
+    m.push(Value::new(l.merge(&r, mc)));
     Step::Continue(())
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_neg(&mut self, reader: &mut BytecodeReader<'_>, mc: &Mutation<'gc>) -> Step {
-        let rhs = self.force_and_retry::<NixNum>(reader, mc)?;
+#[inline(always)]
+pub(crate) fn op_neg<'gc, M: Machine<'gc>>(
+    m: &mut M,
+    reader: &mut BytecodeReader<'_>,
+    mc: &Mutation<'gc>,
+) -> Step {
+    let rhs = m.force_and_retry::<NixNum>(reader, mc)?;
     match rhs {
-            NixNum::Int(int) => self.push(Value::make_int(-int, mc)),
-            NixNum::Float(float) => self.push(Value::new_float(-float)),
+        NixNum::Int(int) => m.push(Value::make_int(-int, mc)),
+        NixNum::Float(float) => m.push(Value::new(-float)),
     }
     Step::Continue(())
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_not(&mut self, reader: &mut BytecodeReader<'_>, mc: &Mutation<'gc>) -> Step {
-        let rhs = self.force_and_retry::<bool>(reader, mc)?;
-        self.push(Value::new_inline(!rhs));
+#[inline(always)]
+pub(crate) fn op_not<'gc, M: Machine<'gc>>(
+    m: &mut M,
+    reader: &mut BytecodeReader<'_>,
+    mc: &Mutation<'gc>,
+) -> Step {
+    let rhs = m.force_and_retry::<bool>(reader, mc)?;
+    m.push(Value::new(!rhs));
     Step::Continue(())
-    }
+}
 
-    fn compare_values_inner(
-        &mut self,
+fn compare_values_inner<'gc, M: Machine<'gc>>(
+    m: &mut M,
     ctx: &impl VmRuntimeCtx,
     pred: fn(Ordering) -> bool,
     lhs: StrictValue<'gc>,
     rhs: StrictValue<'gc>,
-    ) -> crate::VmResult<()> {
+) -> crate::VmResult<()> {
     if let (Some(a), Some(b)) = (get_num(lhs), get_num(rhs)) {
         let ord = match (a, b) {
             (NixNum::Int(a), NixNum::Int(b)) => a.cmp(&b),
@@ -244,31 +263,34 @@ impl<'gc> crate::Vm<'gc> {
                 a.partial_cmp(&(b as f64)).unwrap_or(Ordering::Less)
             }
         };
-            self.push(Value::new_inline(pred(ord)));
+        m.push(Value::new(pred(ord)));
         return Ok(());
     }
     if let (Some(a), Some(b)) = (ctx.get_string(lhs), ctx.get_string(rhs)) {
-            self.push(Value::new_inline(pred(a.cmp(b))));
+        m.push(Value::new(pred(a.cmp(b))));
         return Ok(());
     }
-        if let (Some(a), Some(b)) = (lhs.as_inline::<Path>(), rhs.as_inline::<Path>()) {
+    if let (Some(a), Some(b)) = (lhs.downcast::<Path>(), rhs.downcast::<Path>()) {
         let a = ctx.resolve_string(a.0);
         let b = ctx.resolve_string(b.0);
-            self.push(Value::new_inline(pred(a.cmp(b))));
+        m.push(Value::new(pred(a.cmp(b))));
         return Ok(());
     }
     // TODO: compare other types
-        Err(crate::vm_err("cannot compare these types"))
-    }
+    Err(crate::vm_err(format!(
+        "cannot compare {} with {}",
+        lhs.ty(),
+        rhs.ty()
+    )))
 }
 
 pub(crate) fn get_num(val: StrictValue<'_>) -> Option<NixNum> {
-    if let Some(i) = val.as_inline::<i32>() {
-        Some(NixNum::Int(i as i64))
-    } else if let Some(gc_i) = val.as_gc::<i64>() {
+    if let Some(i) = val.downcast::<i32>() {
+        Some(NixNum::Int(i64::from(i)))
+    } else if let Some(gc_i) = val.downcast::<i64>() {
         Some(NixNum::Int(*gc_i))
     } else {
-        val.as_float().map(NixNum::Float)
+        val.downcast::<f64>().map(NixNum::Float)
     }
 }
 
@@ -282,13 +304,9 @@ fn numeric_binop<'gc>(
 ) -> crate::VmResult<Value<'gc>> {
     match (get_num(lhs), get_num(rhs)) {
         (Some(NixNum::Int(a)), Some(NixNum::Int(b))) => Ok(Value::make_int(int_op(a, b), mc)),
-        (Some(NixNum::Float(a)), Some(NixNum::Float(b))) => Ok(Value::new_float(float_op(a, b))),
-        (Some(NixNum::Int(a)), Some(NixNum::Float(b))) => {
-            Ok(Value::new_float(float_op(a as f64, b)))
-        }
-        (Some(NixNum::Float(a)), Some(NixNum::Int(b))) => {
-            Ok(Value::new_float(float_op(a, b as f64)))
-        }
+        (Some(NixNum::Float(a)), Some(NixNum::Float(b))) => Ok(Value::new(float_op(a, b))),
+        (Some(NixNum::Int(a)), Some(NixNum::Float(b))) => Ok(Value::new(float_op(a as f64, b))),
+        (Some(NixNum::Float(a)), Some(NixNum::Int(b))) => Ok(Value::new(float_op(a, b as f64))),
         _ => Err(crate::vm_err(format!(
             "cannot perform arithmetic on non-numbers: {:?}",
             (lhs.ty(), rhs.ty())

fix-vm/src/instructions/calls.rs

@@ -1,6 +1,6 @@
-use fix_abstract_vm::{resolve_operand, *};
-use fix_builtins::PrimOpPhase;
+use fix_bytecode::Continuation;
 use fix_error::Error;
+use fix_runtime::{resolve_operand, *};
 use gc_arena::{Gc, Mutation, RefLock};
 
 use crate::{
@@ -8,31 +8,35 @@ use crate::{
     VmRuntimeCtxExt,
 };
 
-impl<'gc> crate::Vm<'gc> {
-    #[inline(always)]
-    pub(crate) fn call(
-        &mut self,
+#[inline(always)]
+#[expect(
+    clippy::indexing_slicing,
+    reason = "app.args is a fixed [Value; 3]; indices are bounded by primop arity (<= 3) validated at PrimOpApp construction"
+)]
+pub(crate) fn call<'gc, M: Machine<'gc>>(
+    m: &mut M,
     reader: &mut BytecodeReader<'_>,
     mc: &Mutation<'gc>,
     arg: Value<'gc>,
     resume_pc: usize,
-    ) -> Step {
-        let func = self.force_and_retry::<StrictValue>(reader, mc)?;
-        if self.call_depth > 10000 {
-            return self.finish_err(Error::eval_error("stack overflow; max-call-depth exceeded"));
+) -> Step {
+    let func = m.force_and_retry::<StrictValue>(reader, mc)?;
+    if m.call_depth() > 10000 {
+        return m.finish_err(Error::eval_error("stack overflow; max-call-depth exceeded"));
     }
-        self.call_depth += 1;
-        if let Some(closure) = func.as_gc::<Closure>() {
+    m.inc_call_depth();
+    if let Some(closure) = func.downcast::<Closure>() {
         if closure.pattern.is_some() {
             // FIXME: better DX...
-                self.push(func.relax());
-                self.push(arg);
-                self.call_stack.push(CallFrame {
+            m.push(func.relax());
+            m.push(arg);
+            m.push_call_frame(CallFrame {
                 pc: resume_pc,
                 thunk: None,
-                    env: self.env,
+                env: m.env(),
+                depth: None,
             });
-                reader.set_pc(PrimOpPhase::CallPattern.ip() as usize);
+            reader.set_pc(Continuation::CallPattern.ip() as usize);
             return Step::Continue(());
         }
 
@@ -40,20 +44,22 @@ impl<'gc> crate::Vm<'gc> {
         let n_locals = closure.n_locals;
         let env = closure.env;
         let new_env = Gc::new(mc, RefLock::new(Env::with_arg(arg, n_locals, env)));
-            self.call_stack.push(CallFrame {
+        m.push_call_frame(CallFrame {
             pc: resume_pc,
             thunk: None,
-                env: self.env,
+            env: m.env(),
+            depth: None,
         });
         reader.set_pc(ip as usize);
-            self.env = new_env;
-        } else if let Some(primop) = func.as_inline::<PrimOp>() {
+        m.set_env(new_env);
+    } else if let Some(primop) = func.downcast::<PrimOp>() {
         if primop.arity == 1 {
-                self.push(arg);
-                self.call_stack.push(CallFrame {
+            m.push(arg);
+            m.push_call_frame(CallFrame {
                 pc: resume_pc,
                 thunk: None,
-                    env: self.env,
+                env: m.env(),
+                depth: None,
             });
             reader.set_pc(primop.dispatch_ip as usize)
         } else {
@@ -62,18 +68,19 @@ impl<'gc> crate::Vm<'gc> {
                 arity: primop.arity - 1,
                 args: [arg, Value::default(), Value::default()],
             };
-                self.push(Value::new_gc(Gc::new(mc, app)));
+            m.push(Value::new(Gc::new(mc, app)));
         }
-        } else if let Some(app) = func.as_gc::<PrimOpApp>() {
+    } else if let Some(app) = func.downcast::<PrimOpApp>() {
         if app.arity == 1 {
             for i in 0..app.primop.arity - 1 {
-                    self.push(app.args[i as usize]);
+                m.push(app.args[i as usize]);
             }
-                self.push(arg);
-                self.call_stack.push(CallFrame {
+            m.push(arg);
+            m.push_call_frame(CallFrame {
                 pc: resume_pc,
                 thunk: None,
-                    env: self.env,
+                env: m.env(),
+                depth: None,
             });
             reader.set_pc(app.primop.dispatch_ip as usize)
         } else {
@@ -83,79 +90,82 @@ impl<'gc> crate::Vm<'gc> {
                 ..*app
             };
             new_app.args[position] = arg;
-                self.push(Value::new_gc(Gc::new(mc, new_app)))
+            m.push(Value::new(Gc::new(mc, new_app)))
         }
-        } else if let Some(attrs) = func.as_gc::<AttrSet>()
-            && let Some(functor) = attrs.lookup(self.functor_sym)
+    } else if let Some(attrs) = func.downcast::<AttrSet>()
+        && let Some(functor) = attrs.lookup(m.functor_sym())
     {
         // f arg  =>  (f.__functor f) arg
         //
         // Stage the work for `CallFunctor1` so retries during force are
         // safe: the stack invariant `[..., orig_arg, self, functor]`
         // holds every time control re-enters phase 1.
-            self.call_depth -= 1;
-            self.call_stack.push(CallFrame {
+        m.dec_call_depth();
+        m.push_call_frame(CallFrame {
             pc: resume_pc,
             thunk: None,
-                env: self.env,
+            env: m.env(),
+            depth: None,
         });
-            self.push(arg);
-            self.push(func.relax());
-            self.push(functor);
-            reader.set_pc(PrimOpPhase::CallFunctor1.ip() as usize);
+        m.push(arg);
+        m.push(func.relax());
+        m.push(functor);
+        reader.set_pc(Continuation::CallFunctor1.ip() as usize);
         return Step::Continue(());
     } else {
-            return self.finish_err(Error::eval_error(format!(
+        return m.finish_err(Error::eval_error(format!(
             "attempt to call something which is not a function but {}",
             func.ty()
         )));
     }
     Step::Continue(())
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_call(
-        &mut self,
+#[inline(always)]
+pub(crate) fn op_call<'gc, M: Machine<'gc>>(
+    m: &mut M,
     ctx: &impl VmRuntimeCtx,
     reader: &mut BytecodeReader<'_>,
     mc: &Mutation<'gc>,
-    ) -> Step {
-        let arg = resolve_operand(&reader.read_operand_data(ctx), mc, self);
+) -> Step {
+    let arg = resolve_operand(&reader.read_operand_data(), mc, ctx, m);
     let pc = reader.pc();
-        self.call(reader, mc, arg, pc)
-    }
+    m.call(reader, mc, arg, pc)
+}
 
-    #[inline(always)]
-    pub(crate) fn op_return(
-        &mut self,
+#[inline(always)]
+pub(crate) fn op_return<'gc, M: Machine<'gc>>(
+    m: &mut M,
     ctx: &mut impl VmRuntimeCtx,
     reader: &mut BytecodeReader<'_>,
     mc: &Mutation<'gc>,
-    ) -> Step {
-        let val = self.force_and_retry::<StrictValue>(reader, mc)?;
+) -> Step {
+    let val = m.force_and_retry::<StrictValue>(reader, mc)?;
     let Some(CallFrame {
         pc: ret_pc,
         thunk,
         env,
-        }) = self.call_stack.pop()
+        depth,
+    }) = m.pop_call_frame()
     else {
-            match self.force_mode {
-                ForceMode::AsIs => return self.finish_ok(ctx.convert_value(val.relax())),
+        match m.force_mode() {
+            ForceMode::AsIs => return m.finish_ok(ctx.convert_value(val.relax())),
             ForceMode::Shallow => {
-                    self.push(val.relax());
-                    reader.set_pc(PrimOpPhase::ForceResultShallow.ip() as usize);
+                m.push(val.relax());
+                reader.set_pc(Continuation::ForceResultShallow.ip() as usize);
                 return Step::Continue(());
             }
             ForceMode::Deep => {
-                    self.push(val.relax());
-                    self.push(val.relax());
-                    self.call_stack.push(CallFrame {
-                        pc: PrimOpPhase::ForceResultDeepFinish.ip() as usize,
+                m.push(val.relax());
+                m.push(val.relax());
+                m.push_call_frame(CallFrame {
+                    pc: Continuation::ForceResultDeepFinish.ip() as usize,
                     thunk: None,
-                        env: self.env,
+                    env: m.env(),
+                    depth: None,
                 });
-                    self.call_depth += 1;
-                    reader.set_pc(PrimOpPhase::DeepSeq.ip() as usize);
+                m.inc_call_depth();
+                reader.set_pc(Continuation::PDeepSeq0.ip() as usize);
                 return Step::Continue(());
             }
         }
@@ -163,21 +173,23 @@ impl<'gc> crate::Vm<'gc> {
     reader.set_pc(ret_pc);
     if let Some(outer_thunk) = thunk {
         *outer_thunk.borrow_mut(mc) = ThunkState::Evaluated(val);
+        if let Some(depth) = depth {
+            m.replace(depth, val.relax());
+        }
     } else {
-            self.call_depth -= 1;
-            self.push(val.relax())
+        m.dec_call_depth();
+        m.push(val.relax())
     }
-        self.env = env;
+    m.set_env(env);
     Step::Continue(())
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_dispatch_primop(
-        &mut self,
+#[inline(always)]
+pub(crate) fn op_dispatch_cont<'gc, M: Machine<'gc>>(
+    m: &mut M,
     ctx: &mut impl VmRuntimeCtx,
     reader: &mut BytecodeReader<'_>,
     mc: &Mutation<'gc>,
-    ) -> Step {
-        fix_primops::dispatch_primop(self, ctx, reader, mc)
-    }
+) -> Step {
+    crate::primops::dispatch_cont(m, ctx, reader, mc)
 }

fix-vm/src/instructions/closures.rs

@@ -1,32 +1,32 @@
+use fix_runtime::Machine;
 use gc_arena::{Gc, Mutation, RefLock};
 
 use crate::{BytecodeReader, Step, ThunkState, Value};
 
-impl<'gc> crate::Vm<'gc> {
-    #[inline(always)]
-    pub(crate) fn op_make_thunk(
-        &mut self,
+#[inline(always)]
+pub(crate) fn op_make_thunk<'gc, M: Machine<'gc>>(
+    m: &mut M,
     reader: &mut BytecodeReader<'_>,
     mc: &Mutation<'gc>,
-    ) -> Step {
+) -> Step {
     let entry_point = reader.read_u32();
     let thunk = Gc::new(
         mc,
         RefLock::new(ThunkState::Pending {
             ip: entry_point as usize,
-                env: self.env,
+            env: m.env(),
         }),
     );
-        self.push(Value::new_gc(thunk));
+    m.push(Value::new(thunk));
     Step::Continue(())
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_make_closure(
-        &mut self,
+#[inline(always)]
+pub(crate) fn op_make_closure<'gc, M: Machine<'gc>>(
+    m: &mut M,
     reader: &mut BytecodeReader<'_>,
     mc: &Mutation<'gc>,
-    ) -> Step {
+) -> Step {
     let entry_point = reader.read_u32();
     let n_locals = reader.read_u32();
     let closure = Gc::new(
@@ -34,20 +34,20 @@ impl<'gc> crate::Vm<'gc> {
         crate::Closure {
             ip: entry_point,
             n_locals,
-                env: self.env,
+            env: m.env(),
             pattern: None,
         },
     );
-        self.push(Value::new_gc(closure));
+    m.push(Value::new(closure));
     Step::Continue(())
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_make_pattern_closure(
-        &mut self,
+#[inline(always)]
+pub(crate) fn op_make_pattern_closure<'gc, M: Machine<'gc>>(
+    m: &mut M,
     reader: &mut BytecodeReader<'_>,
     mc: &Mutation<'gc>,
-    ) -> Step {
+) -> Step {
     let entry_point = reader.read_u32();
     let n_locals = reader.read_u32();
     let req_count = reader.read_u16() as usize;
@@ -84,11 +84,10 @@ impl<'gc> crate::Vm<'gc> {
         crate::Closure {
             ip: entry_point,
             n_locals,
-                env: self.env,
+            env: m.env(),
             pattern: Some(pattern),
         },
     );
-        self.push(Value::new_gc(closure));
+    m.push(Value::new(closure));
     Step::Continue(())
-    }
 }

fix-vm/src/instructions/collections.rs

@@ -1,6 +1,6 @@
-use fix_abstract_vm::{NixType, resolve_operand};
-use fix_common::StringId;
 use fix_error::Error;
+use fix_lang::StringId;
+use fix_runtime::{Machine, MachineExt, NixType, resolve_operand};
 use gc_arena::{Gc, RefLock};
 use smallvec::SmallVec;
 
@@ -8,48 +8,47 @@ use crate::{
     AttrSet, BytecodeReader, List, Step, StrictValue, Value, VmRuntimeCtx, VmRuntimeCtxExt,
 };
 
-impl<'gc> crate::Vm<'gc> {
-    #[inline(always)]
-    pub(crate) fn op_make_attrs(
-        &mut self,
+#[inline(always)]
+pub(crate) fn op_make_attrs<'gc, M: Machine<'gc>>(
+    m: &mut M,
     ctx: &mut impl VmRuntimeCtx,
     reader: &mut BytecodeReader<'_>,
     mc: &gc_arena::Mutation<'gc>,
-    ) -> Step {
+) -> Step {
     let static_count = reader.read_u32() as usize;
     let dynamic_count = reader.read_u32() as usize;
 
     for i in 0..dynamic_count {
         let depth = dynamic_count - 1 - i;
-            self.force_slot_to_pc(depth, reader, mc, reader.inst_start_pc())?;
+        m.force_slot_to_pc(depth, reader, mc, reader.inst_start_pc())?;
     }
 
     let mut dyn_keys: SmallVec<[_; 2]> = SmallVec::with_capacity(dynamic_count);
     for i in 0..dynamic_count {
         let depth = dynamic_count - 1 - i;
-            let key_val = self.peek_forced(depth);
+        let key_val = m.peek_forced(depth);
         let key_sid = match ctx.get_string_id(key_val) {
             Ok(id) => Some(id),
             Err(NixType::Null) => None,
-                Err(got) => return self.finish_type_err(NixType::String, got),
+            Err(got) => return m.finish_type_err(NixType::String, got),
         };
         dyn_keys.push(key_sid);
     }
 
-        self.stack.truncate(self.stack.len() - dynamic_count);
+    m.drop_n(dynamic_count);
 
     let mut kv: SmallVec<[(crate::StringId, Value); 4]> =
         SmallVec::with_capacity(static_count + dynamic_count);
 
     for _ in 0..static_count {
         let key = reader.read_string_id();
-            let val = resolve_operand(&reader.read_operand_data(ctx), mc, self);
+        let val = resolve_operand(&reader.read_operand_data(), mc, ctx, m);
         let _span_id = reader.read_u32();
         kv.push((key, val));
     }
 
     for key in dyn_keys {
-            let val = resolve_operand(&reader.read_operand_data(ctx), mc, self);
+        let val = resolve_operand(&reader.read_operand_data(), mc, ctx, m);
         let _span_id = reader.read_u32();
         if let Some(key) = key {
             kv.push((key, val))
@@ -58,75 +57,80 @@ impl<'gc> crate::Vm<'gc> {
 
     kv.sort_by_key(|(k, _)| *k);
     let attrs = Gc::new(mc, AttrSet::from_sorted_unchecked(kv));
-        self.push(Value::new_gc(attrs));
+    m.push(Value::new(attrs));
     Step::Continue(())
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_make_empty_attrs(&mut self) -> Step {
-        self.push(self.empty_attrs);
+#[inline(always)]
+pub(crate) fn op_make_empty_attrs<'gc, M: Machine<'gc>>(m: &mut M) -> Step {
+    m.push(m.empty_attrs());
     Step::Continue(())
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_select_static(
-        &mut self,
+#[inline(always)]
+pub(crate) fn op_select_static<'gc, M: Machine<'gc>>(
+    m: &mut M,
     ctx: &mut impl VmRuntimeCtx,
     reader: &mut BytecodeReader<'_>,
     mc: &gc_arena::Mutation<'gc>,
-    ) -> Step {
+) -> Step {
     let _span_id = reader.read_u32();
     let key = reader.read_string_id();
 
-        let attrset = self.force_and_retry::<Gc<AttrSet>>(reader, mc)?;
+    let attrset = m.force_and_retry::<Gc<AttrSet>>(reader, mc)?;
 
     match attrset.lookup(key) {
         Some(v) => {
-                self.push(v);
+            m.push(v);
         }
-            None => return self.select_skip(key, ctx, reader),
+        None => return select_skip(m, key, ctx, reader),
     }
     Step::Continue(())
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_select_dynamic(
-        &mut self,
+#[inline(always)]
+pub(crate) fn op_select_dynamic<'gc, M: Machine<'gc>>(
+    m: &mut M,
     ctx: &mut impl VmRuntimeCtx,
     reader: &mut BytecodeReader<'_>,
     mc: &gc_arena::Mutation<'gc>,
-    ) -> Step {
+) -> Step {
     let _span_id = reader.read_u32();
 
-        let (attrset, key_val) = self.force_and_retry::<(Gc<AttrSet>, StrictValue)>(reader, mc)?;
+    let (attrset, key_val) = m.force_and_retry::<(Gc<AttrSet>, StrictValue)>(reader, mc)?;
 
     let key_sid = match ctx.get_string_id(key_val) {
         Ok(id) => id,
-            Err(got) => return self.finish_type_err(NixType::String, got),
+        Err(got) => return m.finish_type_err(NixType::String, got),
     };
 
     match attrset.lookup(key_sid) {
         Some(v) => {
-                self.push(v);
+            m.push(v);
         }
-            None => return self.select_skip(key_sid, ctx, reader),
+        None => return select_skip(m, key_sid, ctx, reader),
     }
     Step::Continue(())
-    }
+}
 
-    /// Skip the rest of a **Select** attrpath after a missing attribute.
-    /// Only recognises Select opcodes and jumps; encountering any other
-    /// opcode means we've reached the end of the select sequence and
-    /// should report the missing-attribute error.
-    fn select_skip(
-        &mut self,
+/// Skip the rest of a **Select** attrpath after a missing attribute.
+/// Only recognises Select opcodes and jumps; encountering any other
+/// opcode means we've reached the end of the select sequence and
+/// should report the missing-attribute error.
+#[expect(
+    clippy::cast_sign_loss,
+    reason = "jump target = pc + offset is a non-negative bytecode address by codegen invariant"
+)]
+fn select_skip<'gc, M: Machine<'gc>>(
+    m: &mut M,
     key: StringId,
     ctx: &mut impl VmRuntimeCtx,
     reader: &mut BytecodeReader<'_>,
-    ) -> Step {
-        use fix_codegen::Op::*;
+) -> Step {
+    use fix_bytecode::Op::*;
     loop {
         match reader.read_op() {
+            // Skip rest of the attrpath
             SelectStatic => {
                 reader.set_pc(reader.pc() + 4 + 4);
             }
@@ -137,23 +141,34 @@ impl<'gc> crate::Vm<'gc> {
                 reader.set_pc(reader.pc() + 4);
                 break Step::Continue(());
             }
+
+            // Default (`a.b or c`)
             JumpIfSelectFailed => {
                 let offset = reader.read_i32();
                 reader.set_pc(((reader.pc() as isize) + (offset as isize)) as usize);
             }
+
+            // Report error
             _ => {
                 let name = ctx.resolve_string(key);
-                    return self
-                        .finish_err(Error::eval_error(format!("attribute '{name}' missing")));
-                }
+                return m.finish_err(Error::eval_error(format!("attribute '{name}' missing")));
             }
         }
     }
+}
 
-    /// Skip the rest of a **HasAttr** attrpath after an intermediate
-    /// lookup failed. Only recognises HasAttr opcodes and jumps.
-    fn has_attr_skip(&mut self, reader: &mut BytecodeReader<'_>) -> Step {
-        use fix_codegen::Op::*;
+/// Skip the rest of a **HasAttr** attrpath after an intermediate
+/// lookup failed. Only recognises HasAttr opcodes and jumps.
+#[expect(
+    clippy::cast_sign_loss,
+    reason = "jump target = pc + offset is a non-negative bytecode address by codegen invariant"
+)]
+#[expect(
+    clippy::unreachable,
+    reason = "has_attr_skip only runs over a codegen-produced HasAttr attrpath sequence; any other opcode is a codegen bug"
+)]
+fn has_attr_skip(reader: &mut BytecodeReader<'_>) -> Step {
+    use fix_bytecode::Op::*;
     loop {
         match reader.read_op() {
             HasAttrPathStatic => {
@@ -182,86 +197,96 @@ impl<'gc> crate::Vm<'gc> {
             }
         }
     }
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_has_attr_path_static(
-        &mut self,
+#[inline(always)]
+pub(crate) fn op_has_attr_path_static<'gc, M: Machine<'gc>>(
+    m: &mut M,
     _ctx: &mut impl VmRuntimeCtx,
     reader: &mut BytecodeReader<'_>,
     mc: &gc_arena::Mutation<'gc>,
-    ) -> Step {
+) -> Step {
     let _span_id = reader.read_u32();
     let key = reader.read_string_id();
 
-        let current = self.force_and_retry::<StrictValue>(reader, mc)?;
+    let current = m.force_and_retry::<StrictValue>(reader, mc)?;
 
     match current
-            .as_gc::<AttrSet>()
+        .downcast::<AttrSet>()
         .and_then(|attrs| attrs.lookup(key))
     {
         Some(v) => {
-                self.push(v);
+            m.push(v);
         }
-            None => return self.has_attr_skip(reader),
+        None => return has_attr_skip(reader),
     }
     Step::Continue(())
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_has_attr_path_dynamic(
-        &mut self,
+#[inline(always)]
+pub(crate) fn op_has_attr_path_dynamic<'gc, M: Machine<'gc>>(
+    m: &mut M,
     ctx: &mut impl VmRuntimeCtx,
     reader: &mut BytecodeReader<'_>,
     mc: &gc_arena::Mutation<'gc>,
-    ) -> Step {
+) -> Step {
     let _span_id = reader.read_u32();
 
-        let (current, key_val) = self.force_and_retry::<(StrictValue, StrictValue)>(reader, mc)?;
+    let (current, key_val) = m.force_and_retry::<(StrictValue, StrictValue)>(reader, mc)?;
 
     let key_sid = match ctx.get_string_id(key_val) {
         Ok(id) => id,
-            Err(got) => return self.finish_type_err(NixType::String, got),
+        Err(got) => return m.finish_type_err(NixType::String, got),
     };
 
     match current
-            .as_gc::<AttrSet>()
+        .downcast::<AttrSet>()
         .and_then(|attrs| attrs.lookup(key_sid))
     {
         Some(v) => {
-                self.push(v);
+            m.push(v);
         }
-            None => return self.has_attr_skip(reader),
+        None => return has_attr_skip(reader),
     }
     Step::Continue(())
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_jump_if_select_failed(&mut self, reader: &mut BytecodeReader<'_>) -> Step {
+#[inline(always)]
+pub(crate) fn op_jump_if_select_failed<'gc, M: Machine<'gc>>(
+    _m: &mut M,
+    reader: &mut BytecodeReader<'_>,
+) -> Step {
     // No-op
     let _offset = reader.read_i32();
     Step::Continue(())
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_jump_if_select_succeeded(&mut self, reader: &mut BytecodeReader<'_>) -> Step {
+#[inline(always)]
+#[expect(
+    clippy::cast_sign_loss,
+    reason = "jump target = pc + offset is a non-negative bytecode address by codegen invariant"
+)]
+pub(crate) fn op_jump_if_select_succeeded<'gc, M: Machine<'gc>>(
+    _m: &mut M,
+    reader: &mut BytecodeReader<'_>,
+) -> Step {
     let offset = reader.read_i32();
     reader.set_pc(((reader.pc() as isize) + (offset as isize)) as usize);
     Step::Continue(())
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_has_attr_static(
-        &mut self,
+#[inline(always)]
+pub(crate) fn op_has_attr_static<'gc, M: Machine<'gc>>(
+    m: &mut M,
     reader: &mut BytecodeReader<'_>,
     mc: &gc_arena::Mutation<'gc>,
-    ) -> Step {
+) -> Step {
     let key = reader.read_string_id();
-        let current = self.force_and_retry::<StrictValue>(reader, mc)?;
+    let current = m.force_and_retry::<StrictValue>(reader, mc)?;
 
-        self.push(Value::new_inline(
+    m.push(Value::new(
         current
-                .as_gc::<AttrSet>()
+            .downcast::<AttrSet>()
             .and_then(|attrs| attrs.lookup(key))
             .is_some(),
     ));
@@ -269,25 +294,25 @@ impl<'gc> crate::Vm<'gc> {
     reader.set_pc(reader.pc() + 1);
 
     Step::Continue(())
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_has_attr_dynamic(
-        &mut self,
+#[inline(always)]
+pub(crate) fn op_has_attr_dynamic<'gc, M: MachineExt<'gc>>(
+    m: &mut M,
     ctx: &mut impl VmRuntimeCtx,
     reader: &mut BytecodeReader<'_>,
     mc: &gc_arena::Mutation<'gc>,
-    ) -> Step {
-        let (current, dyn_key) = self.force_and_retry::<(StrictValue, StrictValue)>(reader, mc)?;
+) -> Step {
+    let (current, dyn_key) = m.force_and_retry::<(StrictValue, StrictValue)>(reader, mc)?;
 
     let key_sid = match ctx.get_string_id(dyn_key) {
         Ok(id) => id,
-            Err(got) => return self.finish_type_err(NixType::String, got),
+        Err(got) => return m.finish_type_err(NixType::String, got),
     };
 
-        self.push(Value::new_inline(
+    m.push(Value::new(
         current
-                .as_gc::<AttrSet>()
+            .downcast::<AttrSet>()
             .and_then(|attrs| attrs.lookup(key_sid))
             .is_some(),
     ));
@@ -295,26 +320,26 @@ impl<'gc> crate::Vm<'gc> {
     reader.set_pc(reader.pc() + 1);
 
     Step::Continue(())
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_has_attr_resolve(&mut self) -> Step {
+#[inline(always)]
+pub(crate) fn op_has_attr_resolve<'gc, M: Machine<'gc>>(m: &mut M) -> Step {
     // If we reach here, has_attr check has failed, push false (AttrSet is already popped)
-        self.push(Value::new_inline(false));
+    m.push(Value::new(false));
     Step::Continue(())
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_make_list(
-        &mut self,
+#[inline(always)]
+pub(crate) fn op_make_list<'gc, M: Machine<'gc>>(
+    m: &mut M,
     ctx: &mut impl VmRuntimeCtx,
     reader: &mut BytecodeReader<'_>,
     mc: &gc_arena::Mutation<'gc>,
-    ) -> Step {
+) -> Step {
     let count = reader.read_u32() as usize;
     let mut items: SmallVec<[Value; 4]> = SmallVec::with_capacity(count);
     for _ in 0..count {
-            items.push(resolve_operand(&reader.read_operand_data(ctx), mc, self));
+        items.push(resolve_operand(&reader.read_operand_data(), mc, ctx, m));
     }
     let list = Gc::new(
         mc,
@@ -322,13 +347,12 @@ impl<'gc> crate::Vm<'gc> {
             inner: RefLock::new(items),
         },
     );
-        self.push(Value::new_gc(list));
+    m.push(Value::new(list));
+    Step::Continue(())
+}
+
+#[inline(always)]
+pub(crate) fn op_make_empty_list<'gc, M: Machine<'gc>>(m: &mut M) -> Step {
+    m.push(m.empty_list());
     Step::Continue(())
-    }
-
-    #[inline(always)]
-    pub(crate) fn op_make_empty_list(&mut self) -> Step {
-        self.push(self.empty_list);
-        Step::Continue(())
-    }
 }

fix-vm/src/instructions/control.rs

@@ -1,60 +1,70 @@
-use fix_abstract_vm::*;
 use fix_error::Error;
+use fix_runtime::*;
 use gc_arena::Mutation;
 
 use crate::{BytecodeReader, Step, VmRuntimeCtx};
 
-impl<'gc> crate::Vm<'gc> {
-    #[inline(always)]
-    pub(crate) fn op_jump_if_false(
-        &mut self,
+#[inline(always)]
+#[expect(
+    clippy::cast_sign_loss,
+    reason = "jump target = pc + offset is a non-negative bytecode address by codegen invariant"
+)]
+pub(crate) fn op_jump_if_false<'gc, M: Machine<'gc>>(
+    m: &mut M,
     reader: &mut BytecodeReader<'_>,
     mc: &gc_arena::Mutation<'gc>,
-    ) -> Step {
+) -> Step {
     let offset = reader.read_i32();
-        let cond = self.force_and_retry::<StrictValue>(reader, mc)?;
-        if cond.as_inline::<bool>() == Some(false) {
+    let cond = m.force_and_retry::<StrictValue>(reader, mc)?;
+    if cond.downcast::<bool>() == Some(false) {
         reader.set_pc(((reader.pc() as isize) + (offset as isize)) as usize);
     }
     Step::Continue(())
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_jump_if_true(
-        &mut self,
+#[inline(always)]
+#[expect(
+    clippy::cast_sign_loss,
+    reason = "jump target = pc + offset is a non-negative bytecode address by codegen invariant"
+)]
+pub(crate) fn op_jump_if_true<'gc, M: Machine<'gc>>(
+    m: &mut M,
     reader: &mut BytecodeReader<'_>,
     mc: &Mutation<'gc>,
-    ) -> Step {
+) -> Step {
     let offset = reader.read_i32();
-        let cond = self.force_and_retry::<StrictValue>(reader, mc)?;
-        if cond.as_inline::<bool>() == Some(true) {
+    let cond = m.force_and_retry::<StrictValue>(reader, mc)?;
+    if cond.downcast::<bool>() == Some(true) {
         reader.set_pc(((reader.pc() as isize) + (offset as isize)) as usize);
     }
     Step::Continue(())
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_jump(&mut self, reader: &mut BytecodeReader<'_>) -> Step {
+#[inline(always)]
+#[expect(
+    clippy::cast_sign_loss,
+    reason = "jump target = pc + offset is a non-negative bytecode address by codegen invariant"
+)]
+pub(crate) fn op_jump<'gc, M: Machine<'gc>>(_m: &mut M, reader: &mut BytecodeReader<'_>) -> Step {
     let offset = reader.read_i32();
     reader.set_pc(((reader.pc() as isize) + (offset as isize)) as usize);
     Step::Continue(())
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_assert(
-        &mut self,
+#[inline(always)]
+pub(crate) fn op_assert<'gc, M: Machine<'gc>>(
+    m: &mut M,
     ctx: &mut impl VmRuntimeCtx,
     reader: &mut BytecodeReader<'_>,
     mc: &Mutation<'gc>,
-    ) -> Step {
+) -> Step {
     let raw_id = reader.read_string_id();
     let raw = ctx.resolve_string(raw_id);
     let _span_id = reader.read_u32();
-        let assertion = self.force_and_retry::<bool>(reader, mc)?;
+    let assertion = m.force_and_retry::<bool>(reader, mc)?;
     if !assertion {
         // FIXME: use catchable error
-            return self.finish_err(Error::eval_error(format!("assertion '{raw}' failed")));
+        return m.finish_err(Error::eval_error(format!("assertion '{raw}' failed")));
     }
     Step::Continue(())
-    }
 }

fix-vm/src/instructions/literals.rs

@@ -1,55 +1,63 @@
+use fix_runtime::Machine;
 use gc_arena::{Gc, Mutation};
 
 use crate::{BytecodeReader, Step, Value};
 
-impl<'gc> crate::Vm<'gc> {
-    #[inline(always)]
-    pub(crate) fn op_push_smi(&mut self, reader: &mut BytecodeReader<'_>) -> Step {
+#[inline(always)]
+pub(crate) fn op_push_smi<'gc, M: Machine<'gc>>(
+    m: &mut M,
+    reader: &mut BytecodeReader<'_>,
+) -> Step {
     let val = reader.read_i32();
-        self.push(Value::new_inline(val));
+    m.push(Value::new(val));
     Step::Continue(())
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_push_bigint(
-        &mut self,
+#[inline(always)]
+pub(crate) fn op_push_bigint<'gc, M: Machine<'gc>>(
+    m: &mut M,
     reader: &mut BytecodeReader<'_>,
     mc: &Mutation<'gc>,
-    ) -> Step {
+) -> Step {
     let val = reader.read_i64();
-        self.push(Value::new_gc(Gc::new(mc, val)));
+    m.push(Value::new(Gc::new(mc, val)));
+    Step::Continue(())
+}
+
+#[inline(always)]
+pub(crate) fn op_push_float<'gc, M: Machine<'gc>>(
+    m: &mut M,
+    reader: &mut BytecodeReader<'_>,
+) -> Step {
+    let val = reader.read_f64();
+    m.push(Value::new(val));
+    Step::Continue(())
+}
+
+#[inline(always)]
+pub(crate) fn op_push_string<'gc, M: Machine<'gc>>(
+    m: &mut M,
+    reader: &mut BytecodeReader<'_>,
+) -> Step {
+    let sid = reader.read_string_id();
+    m.push(Value::new(sid));
+    Step::Continue(())
+}
+
+#[inline(always)]
+pub(crate) fn op_push_null<'gc, M: Machine<'gc>>(m: &mut M) -> Step {
+    m.push(Value::new(crate::Null));
+    Step::Continue(())
+}
+
+#[inline(always)]
+pub(crate) fn op_push_true<'gc, M: Machine<'gc>>(m: &mut M) -> Step {
+    m.push(Value::new(true));
+    Step::Continue(())
+}
+
+#[inline(always)]
+pub(crate) fn op_push_false<'gc, M: Machine<'gc>>(m: &mut M) -> Step {
+    m.push(Value::new(false));
     Step::Continue(())
-    }
-
-    #[inline(always)]
-    pub(crate) fn op_push_float(&mut self, reader: &mut BytecodeReader<'_>) -> Step {
-        let val = reader.read_f64();
-        self.push(Value::new_float(val));
-        Step::Continue(())
-    }
-
-    #[inline(always)]
-    pub(crate) fn op_push_string(&mut self, reader: &mut BytecodeReader<'_>) -> Step {
-        let sid = reader.read_string_id();
-        self.push(Value::new_inline(sid));
-        Step::Continue(())
-    }
-
-    #[inline(always)]
-    pub(crate) fn op_push_null(&mut self) -> Step {
-        self.push(Value::new_inline(crate::Null));
-        Step::Continue(())
-    }
-
-    #[inline(always)]
-    pub(crate) fn op_push_true(&mut self) -> Step {
-        self.push(Value::new_inline(true));
-        Step::Continue(())
-    }
-
-    #[inline(always)]
-    pub(crate) fn op_push_false(&mut self) -> Step {
-        self.push(Value::new_inline(false));
-        Step::Continue(())
-    }
 }

fix-vm/src/instructions/misc.rs

@@ -1,105 +1,106 @@
 use std::path::PathBuf;
 
-use fix_abstract_vm::{
-    AttrSet, NixString, Path, StrictValue, StringContext, canon_path_str
-};
-use fix_builtins::BuiltinId;
-use fix_common::StringId;
+use fix_bytecode::Continuation;
 use fix_error::Error;
-use num_enum::TryFromPrimitive;
+use fix_lang::{BuiltinId, StringId};
+use fix_runtime::{
+    AttrSet, Machine, MachineExt, NixString, Path, StrictValue, StringContext, canon_path_str,
+};
 
 use crate::{BytecodeReader, PrimOp, Step, Value, VmRuntimeCtx, VmRuntimeCtxExt};
 
-impl<'gc> crate::Vm<'gc> {
-    #[inline(always)]
-    pub(crate) fn op_load_builtins(&mut self) -> Step {
-        self.push(self.builtins);
+#[inline(always)]
+pub(crate) fn op_load_builtins<'gc, M: Machine<'gc>>(m: &mut M) -> Step {
+    m.push(m.builtins().into());
     Step::Continue(())
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_load_builtin(&mut self, reader: &mut BytecodeReader<'_>) -> Step {
-        let Ok(id) = BuiltinId::try_from_primitive(reader.read_u8())
+#[inline(always)]
+#[expect(
+    clippy::panic,
+    reason = "codegen only emits LoadBuiltin with valid BuiltinId bytes; an unknown id is a codegen/bytecode-corruption bug"
+)]
+pub(crate) fn op_load_builtin<'gc, M: Machine<'gc>>(
+    m: &mut M,
+    reader: &mut BytecodeReader<'_>,
+) -> Step {
+    let Ok(id) = BuiltinId::try_from(reader.read_u8())
         .map_err(|err| panic!("unknown builtin id: {}", err.number));
-        self.push(Value::new_inline(PrimOp {
+    m.push(Value::new(PrimOp {
         id,
-            arity: fix_builtins::BUILTINS[id as usize].1,
-            dispatch_ip: id.entry_phase().ip(),
+        arity: id.info().arity,
+        dispatch_ip: Continuation::entry_for_builtin(id).ip(),
     }));
     Step::Continue(())
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_load_repl_binding(&mut self, reader: &mut BytecodeReader<'_>) -> Step {
+#[inline(always)]
+pub(crate) fn op_load_repl_binding<'gc, M: Machine<'gc>>(
+    _m: &mut M,
+    reader: &mut BytecodeReader<'_>,
+) -> Step {
     let _name = reader.read_string_id();
     todo!("LoadReplBinding");
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_load_scoped_binding(
-        &mut self,
+#[inline(always)]
+pub(crate) fn op_load_scoped_binding<'gc, M: Machine<'gc>>(
+    m: &mut M,
     ctx: &impl VmRuntimeCtx,
     reader: &mut BytecodeReader<'_>,
     _mc: &gc_arena::Mutation<'gc>,
-    ) -> Step {
+) -> Step {
     let slot_id = reader.read_u32();
     let name = reader.read_string_id();
-        let scope = match self.scope_slots.get(slot_id as usize).copied() {
-            Some(s) => s,
-            None => {
-                return self.finish_err(Error::eval_error(format!(
-                    "internal: invalid scope slot {slot_id}"
-                )));
-            }
-        };
-        let Some(attrs) = scope.as_gc::<AttrSet>() else {
-            return self.finish_err(Error::eval_error("internal: scope slot is not an attrset"));
+    let scope = m.scope_slot(slot_id);
+    let Some(attrs) = scope.downcast::<AttrSet>() else {
+        return m.finish_err(Error::eval_error("internal: scope slot is not an attrset"));
     };
     match attrs.lookup(name) {
         Some(val) => {
-                self.push(val);
+            m.push(val);
             Step::Continue(())
         }
-            None => self.finish_err(Error::eval_error(format!(
+        None => m.finish_err(Error::eval_error(format!(
             "scoped binding '{}' not found",
             ctx.resolve_string(name)
         ))),
     }
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_coerce_to_string(
-        &mut self,
+#[inline(always)]
+pub(crate) fn op_coerce_to_string<'gc, M: Machine<'gc>>(
+    m: &mut M,
     reader: &mut BytecodeReader<'_>,
     mc: &gc_arena::Mutation<'gc>,
-    ) -> Step {
-        let val = self.force_and_retry::<StrictValue>(reader, mc)?;
+) -> Step {
+    let val = m.force_and_retry::<StrictValue>(reader, mc)?;
     if val.is::<StringId>() || val.is::<NixString>() {
-            self.push(val.relax());
-        } else if let Some(p) = val.as_inline::<Path>() {
+        m.push(val.relax());
+    } else if let Some(p) = val.downcast::<Path>() {
         // Coercing a path to a string yields the canonical path text.
         // FIXME: copy to store
-            self.push(Value::new_inline(p.0));
+        m.push(Value::new(p.0));
     } else {
         todo!("coerce other types to string: {:?}", val.ty());
     }
     Step::Continue(())
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_concat_strings(
-        &mut self,
+#[inline(always)]
+pub(crate) fn op_concat_strings<'gc, M: Machine<'gc>>(
+    m: &mut M,
     ctx: &mut impl VmRuntimeCtx,
     reader: &mut BytecodeReader<'_>,
     mc: &gc_arena::Mutation<'gc>,
-    ) -> Step {
+) -> Step {
     let count = reader.read_u16() as usize;
     let _force_string = reader.read_u8() != 0;
 
     let mut total_len = 0;
     let mut has_any_context = false;
     for i in 0..count {
-            let val = self.peek_forced(count - 1 - i);
+        let val = m.peek_forced(count - 1 - i);
         let s = ctx.get_string(val).expect("coerced");
         total_len += s.len();
         if !ctx.get_string_context(val).is_empty() {
@@ -110,7 +111,7 @@ impl<'gc> crate::Vm<'gc> {
     let mut result = String::with_capacity(total_len);
     let mut merged = StringContext::new();
     for i in 0..count {
-            let val = self.peek_forced(count - 1 - i);
+        let val = m.peek_forced(count - 1 - i);
         let s = ctx.get_string(val).expect("coerced");
         result.push_str(s);
         if has_any_context {
@@ -121,36 +122,36 @@ impl<'gc> crate::Vm<'gc> {
         }
     }
 
-        self.stack.truncate(self.stack.len() - count);
+    m.drop_n(count);
 
     if merged.is_empty() {
         let sid = ctx.intern_string(result);
-            self.push(Value::new_inline(sid));
+        m.push(Value::new(sid));
     } else {
         let ns = gc_arena::Gc::new(mc, NixString::with_context(result, merged));
-            self.push(Value::new_gc(ns));
+        m.push(Value::new(ns));
     }
     Step::Continue(())
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_resolve_path(
-        &mut self,
+#[inline(always)]
+pub(crate) fn op_resolve_path<'gc, M: MachineExt<'gc>>(
+    m: &mut M,
     ctx: &mut impl VmRuntimeCtx,
     reader: &mut BytecodeReader<'_>,
     mc: &gc_arena::Mutation<'gc>,
-    ) -> Step {
-        let path_val = self.force_and_retry::<StrictValue>(reader, mc)?;
+) -> Step {
+    let path_val = m.force_and_retry::<StrictValue>(reader, mc)?;
     let dir_id = reader.read_string_id();
     // Already a path: keep as-is. ResolvePath is idempotent on paths.
-        if let Some(p) = path_val.as_inline::<Path>() {
-            self.push(Value::new_inline(p));
+    if let Some(p) = path_val.downcast::<Path>() {
+        m.push(Value::new(p));
         return Step::Continue(());
     }
     let path = match ctx.get_string(path_val) {
         Some(s) => s.to_owned(),
         None => {
-                return self.finish_err(Error::eval_error(format!(
+            return m.finish_err(Error::eval_error(format!(
                 "expected a string for path, got {}",
                 path_val.ty()
             )));
@@ -158,12 +159,11 @@ impl<'gc> crate::Vm<'gc> {
     };
     let resolved = match resolve_path_str(ctx.resolve_string(dir_id), &path) {
         Ok(s) => s,
-            Err(e) => return self.finish_err(e),
+        Err(e) => return m.finish_err(e),
     };
     let sid = ctx.intern_string(resolved);
-        self.push(Value::new_inline(Path(sid)));
+    m.push(Value::new(Path(sid)));
     Step::Continue(())
-    }
 }
 
 fn resolve_path_str(current_dir: &str, path: &str) -> Result<String, Box<Error>> {

fix-vm/src/instructions/mod.rs

@@ -7,3 +7,13 @@ pub(crate) mod literals;
 pub(crate) mod misc;
 pub(crate) mod variables;
 pub(crate) mod with_scope;
+
+pub(crate) use arithmetic::*;
+pub(crate) use calls::*;
+pub(crate) use closures::*;
+pub(crate) use collections::*;
+pub(crate) use control::*;
+pub(crate) use literals::*;
+pub(crate) use misc::*;
+pub(crate) use variables::*;
+pub(crate) use with_scope::*;

fix-vm/src/instructions/variables.rs

@@ -1,50 +1,68 @@
+use fix_runtime::Machine;
+
 use crate::{BytecodeReader, Mutation, Step, Value};
 
-impl<'gc> crate::Vm<'gc> {
-    #[inline(always)]
-    pub(crate) fn op_load_local(&mut self, reader: &mut BytecodeReader<'_>) -> Step {
+#[inline(always)]
+#[expect(
+    clippy::indexing_slicing,
+    reason = "local slot index is produced by codegen and bounded by the frame's AllocLocals count"
+)]
+pub(crate) fn op_load_local<'gc, M: Machine<'gc>>(
+    m: &mut M,
+    reader: &mut BytecodeReader<'_>,
+) -> Step {
     let idx = reader.read_u32() as usize;
-        self.push(self.env.borrow().locals[idx]);
+    m.push(m.env().borrow().locals[idx]);
     Step::Continue(())
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_load_outer(&mut self, reader: &mut BytecodeReader<'_>) -> Step {
+#[inline(always)]
+#[expect(
+    clippy::indexing_slicing,
+    reason = "local slot index is produced by codegen and bounded by the target frame's AllocLocals count"
+)]
+pub(crate) fn op_load_outer<'gc, M: Machine<'gc>>(
+    m: &mut M,
+    reader: &mut BytecodeReader<'_>,
+) -> Step {
     let layer = reader.read_u8();
     let idx = reader.read_u32() as usize;
-        let mut cur = self.env;
+    let mut cur = m.env();
     for _ in 0..layer {
         let prev = cur.borrow().prev.expect("LoadOuter: env chain too short");
         cur = prev;
     }
     let val = cur.borrow().locals[idx];
-        self.push(val);
+    m.push(val);
     Step::Continue(())
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_store_local(
-        &mut self,
+#[inline(always)]
+#[expect(
+    clippy::indexing_slicing,
+    reason = "local slot index is produced by codegen and bounded by the frame's AllocLocals count"
+)]
+pub(crate) fn op_store_local<'gc, M: Machine<'gc>>(
+    m: &mut M,
     reader: &mut BytecodeReader<'_>,
     mc: &Mutation<'gc>,
-    ) -> Step {
+) -> Step {
     let idx = reader.read_u32() as usize;
-        let val = self.pop();
-        self.env.borrow_mut(mc).locals[idx] = val;
+    let val = m.pop();
+    m.env().borrow_mut(mc).locals[idx] = val;
     Step::Continue(())
-    }
+}
 
-    #[inline(always)]
-    pub(crate) fn op_alloc_locals(
-        &mut self,
+#[inline(always)]
+pub(crate) fn op_alloc_locals<'gc, M: Machine<'gc>>(
+    m: &mut M,
     reader: &mut BytecodeReader<'_>,
     mc: &Mutation<'gc>,
-    ) -> Step {
+) -> Step {
     let count = reader.read_u32() as usize;
-        self.env
+    m.env()
         .borrow_mut(mc)
         .locals
         .extend(std::iter::repeat_n(Value::default(), count));
     Step::Continue(())
-    }
 }

fix-vm/src/instructions/with_scope.rs

@@ -1,26 +1,32 @@
-use fix_abstract_vm::{resolve_operand, *};
-use fix_common::Symbol;
 use fix_error::Error;
+use fix_lang::Symbol;
+use fix_runtime::{resolve_operand, *};
 use smallvec::SmallVec;
 
 use crate::{Break, BytecodeReader, CallFrame, Step, VmRuntimeCtx};
 
-impl<'gc> crate::Vm<'gc> {
-    #[inline(always)]
-    pub(crate) fn op_lookup_with(
-        &mut self,
+#[inline(always)]
+#[expect(
+    clippy::indexing_slicing,
+    clippy::cast_sign_loss,
+    reason = "counter is a non-negative with-scope index in 0..n, staying within the namespaces vec of length n"
+)]
+pub(crate) fn op_lookup_with<'gc, M: Machine<'gc>>(
+    m: &mut M,
     ctx: &mut impl VmRuntimeCtx,
     reader: &mut BytecodeReader<'_>,
     mc: &gc_arena::Mutation<'gc>,
-    ) -> Step {
-        #[allow(clippy::unwrap_used)]
-        let counter = self.peek_forced(0).as_inline::<i32>().unwrap();
+) -> Step {
+    let counter = m
+        .peek_forced(0)
+        .downcast::<i32>()
+        .expect("stack slot must be an integer");
 
     let name = reader.read_string_id();
     let n = reader.read_u8();
     let mut namespaces = SmallVec::<[_; 2]>::new();
     for _ in 0..n {
-            namespaces.push(resolve_operand(&reader.read_operand_data(ctx), mc, self));
+        namespaces.push(resolve_operand(&reader.read_operand_data(), mc, ctx, m));
     }
 
     let resume_pc = reader.inst_start_pc();
@@ -31,48 +37,48 @@ impl<'gc> crate::Vm<'gc> {
             match *state {
                 ThunkState::Pending { ip, env } => {
                     *state = ThunkState::Blackhole;
-                        self.call_stack.push(CallFrame {
+                    m.push_call_frame(CallFrame {
                         thunk: Some(thunk),
                         pc: resume_pc,
-                            env: self.env,
+                        env: m.env(),
+                        depth: None,
                     });
-                        self.env = env;
+                    m.set_env(env);
                     reader.set_pc(ip);
                     return Step::Break(Break::Force);
                 }
                 ThunkState::Evaluated(v) => v,
                 ThunkState::Apply { func, arg } => {
-                        self.call_stack.push(CallFrame {
+                    m.push_call_frame(CallFrame {
                         thunk: Some(thunk),
                         pc: resume_pc,
-                            env: self.env,
+                        env: m.env(),
+                        depth: None,
                     });
-                        self.push(func);
-                        return self.call(reader, mc, arg, resume_pc);
+                    m.push(func);
+                    return m.call(reader, mc, arg, resume_pc);
                 }
                 ThunkState::Blackhole => {
-                        return self
-                            .finish_err(Error::eval_error("infinite recursion encountered"));
+                    return m.finish_err(Error::eval_error("infinite recursion encountered"));
                 }
             }
         }
     };
 
     if let Some(val) = namespace
-            .as_gc::<AttrSet>()
+        .downcast::<AttrSet>()
         .and_then(|attrs| attrs.lookup(name))
     {
-            self.replace(0, val);
+        m.replace(0, val);
     } else if counter + 1 == n as i32 {
-            return self.finish_err(Error::eval_error(format!(
+        return m.finish_err(Error::eval_error(format!(
             "undefined variable '{}'",
             Symbol::from(ctx.resolve_string(name))
         )));
     } else {
-            self.replace(0, Value::new_inline(counter + 1));
+        m.replace(0, Value::new(counter + 1));
         reader.set_pc(resume_pc);
     }
 
     Step::Continue(())
-    }
 }

fix-vm/src/lib.rs

@@ -1,5 +1,7 @@
-#![warn(clippy::unwrap_used)]
-#![cfg_attr(feature = "tailcall", expect(incomplete_features))]
+#![cfg_attr(
+    feature = "tailcall",
+    expect(incomplete_features, reason = "for testing purpose only")
+)]
 #![cfg_attr(
     feature = "tailcall",
     feature(explicit_tail_calls, rust_preserve_none_cc)
@@ -7,20 +9,23 @@
 
 use std::path::PathBuf;
 
-use fix_builtins::{BUILTINS, BuiltinId};
-use fix_codegen::InstructionPtr;
-use fix_common::StringId;
+use fix_bytecode::{Continuation, InstructionPtr};
 use fix_error::{Error, Result, Source};
+use fix_lang::{BuiltinId, StringId};
 use gc_arena::metrics::Pacing;
 use gc_arena::{Arena, Collect, Gc, Mutation, RefLock, Rootable};
 use hashbrown::HashMap;
-use num_enum::TryFromPrimitive;
 use smallvec::SmallVec;
 
 #[cfg(feature = "tailcall")]
 mod dispatch_tailcall;
-pub use fix_abstract_vm::*;
+pub use fix_runtime::*;
+#[doc(hidden)]
+#[path = "macro_support.rs"]
+pub mod __macro_support;
 mod instructions;
+mod primops;
+extern crate self as fix_vm;
 
 type VmResult<T> = std::result::Result<T, VmError>;
 
@@ -30,7 +35,10 @@ pub struct Vm<'gc> {
     stack: Vec<Value<'gc>>,
     call_stack: Vec<CallFrame<'gc>>,
     call_depth: usize,
-    #[allow(dead_code)]
+    #[expect(
+        dead_code,
+        reason = "error_context is reserved for tryEval catch-frame tracking, not yet wired up"
+    )]
     #[collect(require_static)]
     error_context: Vec<ErrorFrame>,
 
@@ -39,14 +47,14 @@ pub struct Vm<'gc> {
     import_cache: HashMap<PathBuf, Value<'gc>>,
     scope_slots: Vec<Value<'gc>>,
 
-    builtins: Value<'gc>,
+    builtins: Gc<'gc, AttrSet<'gc>>,
     empty_list: Value<'gc>,
     empty_attrs: Value<'gc>,
 
     force_mode: ForceMode,
 
     #[collect(require_static)]
-    result: Option<Result<fix_common::Value>>,
+    result: Option<Result<fix_lang::Value>>,
 
     #[collect(require_static)]
     pending_load: Option<PendingLoad>,
@@ -54,17 +62,16 @@ pub struct Vm<'gc> {
     functor_sym: StringId,
 }
 
-fn init_builtins<'gc>(mc: &Mutation<'gc>, ctx: &mut impl VmRuntimeCtx) -> Value<'gc> {
-    let mut entries = SmallVec::with_capacity(BUILTINS.len());
+fn init_builtins<'gc>(mc: &Mutation<'gc>, ctx: &mut impl VmRuntimeCtx) -> Gc<'gc, AttrSet<'gc>> {
+    let mut entries = SmallVec::with_capacity(BuiltinId::TOTAL);
 
-    for (idx, &(name, arity)) in BUILTINS.iter().enumerate() {
-        let id = BuiltinId::try_from_primitive(idx as u8).expect("infallible");
-        let name = name.strip_prefix("__").unwrap_or(name);
-        let name = ctx.intern_string(name);
-        let dispatch_ip = id.entry_phase().ip();
+    for id in BuiltinId::ALL {
+        let arity = id.info().arity;
+        let name = ctx.intern_string(id.info().name);
+        let dispatch_ip = Continuation::entry_for_builtin(id).ip();
         entries.push((
             name,
-            Value::new_inline(PrimOp {
+            Value::new(PrimOp {
                 id,
                 arity,
                 dispatch_ip,
@@ -75,21 +82,15 @@ fn init_builtins<'gc>(mc: &Mutation<'gc>, ctx: &mut impl VmRuntimeCtx) -> Value<
     let consts = [
         (
             "__currentSystem",
-            Value::new_inline(ctx.intern_string("x86_64-linux")),
+            Value::new(ctx.intern_string("x86_64-linux")),
         ),
-        ("__langVersion", Value::new_inline(6i32)),
-        (
-            "__nixVersion",
-            Value::new_inline(ctx.intern_string("2.24.0")),
-        ),
-        (
-            "__storeDir",
-            Value::new_inline(ctx.intern_string("/nix/store")),
-        ),
-        ("__nixPath", Value::new_gc(Gc::new(mc, List::default()))),
-        ("null", Value::new_inline(Null)),
-        ("true", Value::new_inline(true)),
-        ("false", Value::new_inline(false)),
+        ("__langVersion", Value::new(6i32)),
+        ("__nixVersion", Value::new(ctx.intern_string("2.24.0"))),
+        ("__storeDir", Value::new(ctx.intern_string("/nix/store"))),
+        ("__nixPath", Value::new(Gc::new(mc, List::default()))),
+        ("null", Value::new(Null)),
+        ("true", Value::new(true)),
+        ("false", Value::new(false)),
     ];
 
     for (name, val) in consts {
@@ -100,15 +101,15 @@ fn init_builtins<'gc>(mc: &Mutation<'gc>, ctx: &mut impl VmRuntimeCtx) -> Value<
 
     let self_ref_thunk = Gc::new(mc, RefLock::new(ThunkState::Blackhole));
     let sym = ctx.intern_string("builtins");
-    entries.push((sym, Value::new_gc(self_ref_thunk)));
+    entries.push((sym, Value::new(self_ref_thunk)));
 
     entries.sort_by_key(|(k, _)| *k);
 
     let builtins_set = Gc::new(mc, AttrSet::from_sorted_unchecked(entries));
-    let builtins_value = Value::new_gc(builtins_set);
+    let builtins_value = Value::new(builtins_set);
     *self_ref_thunk.borrow_mut(mc) =
         ThunkState::Evaluated(builtins_value.restrict().expect("builtins is not a thunk"));
-    builtins_value
+    builtins_set
 }
 
 impl<'gc> Vm<'gc> {
@@ -126,8 +127,8 @@ impl<'gc> Vm<'gc> {
             scope_slots: Vec::new(),
 
             builtins,
-            empty_list: Value::new_gc(Gc::new(mc, List::default())),
-            empty_attrs: Value::new_gc(Gc::new(mc, AttrSet::default())),
+            empty_list: Value::new(Gc::new(mc, List::default())),
+            empty_attrs: Value::new(Gc::new(mc, AttrSet::default())),
 
             force_mode,
 
@@ -137,45 +138,20 @@ impl<'gc> Vm<'gc> {
             functor_sym: ctx.intern_string("__functor"),
         }
     }
+}
 
-    #[inline(always)]
-    fn finish_ok(&mut self, val: fix_common::Value) -> Step {
-        self.result = Some(Ok(val));
-        Step::Break(Break::Done)
-    }
-
-    #[inline(always)]
-    fn finish_err(&mut self, err: Box<Error>) -> Step {
-        self.result = Some(Err(err));
-        Step::Break(Break::Done)
-    }
-
-    #[inline(always)]
-    fn finish_type_err(&mut self, expected: NixType, got: NixType) -> Step {
-        self.result = Some(Err(Error::eval_error(format!(
-            "expected {expected}, got {got}"
-        ))));
-        Step::Break(Break::Done)
-    }
-
-    #[inline(always)]
-    fn finish_vm_err(&mut self, err: VmError) -> Step {
-        self.finish_err(err.into_error())
-    }
-
+impl<'gc> Machine<'gc> for Vm<'gc> {
     #[inline(always)]
     fn push(&mut self, val: Value<'gc>) {
         self.stack.push(val);
     }
 
     #[inline(always)]
-    #[must_use]
     fn pop(&mut self) -> Value<'gc> {
         self.stack.pop().expect("stack underflow")
     }
 
     #[inline(always)]
-    #[must_use]
     fn peek(&self, depth: usize) -> Value<'gc> {
         *self
             .stack
@@ -184,7 +160,6 @@ impl<'gc> Vm<'gc> {
     }
 
     #[inline(always)]
-    #[must_use]
     fn peek_forced(&self, depth: usize) -> StrictValue<'gc> {
         self.stack
             .get(self.stack.len() - depth - 1)
@@ -193,6 +168,15 @@ impl<'gc> Vm<'gc> {
             .expect("forced")
     }
 
+    #[inline(always)]
+    fn pop_forced(&mut self) -> StrictValue<'gc> {
+        self.stack
+            .pop()
+            .expect("stack underflow")
+            .restrict()
+            .expect("forced")
+    }
+
     #[inline(always)]
     fn replace(&mut self, depth: usize, val: Value<'gc>) {
         let len = self.stack.len();
@@ -203,147 +187,8 @@ impl<'gc> Vm<'gc> {
     }
 
     #[inline(always)]
-    #[cfg_attr(debug_assertions, track_caller)]
-    fn pop_forced(&mut self) -> StrictValue<'gc> {
-        self.stack
-            .pop()
-            .expect("stack underflow")
-            .restrict()
-            .expect("forced")
-    }
-
-    /// Force the top `T::WIDTH` stack slots and return them as `T`.
-    ///
-    /// If any slot holds a pending thunk, this method pushes a call frame
-    /// whose resume PC is the **start of the current instruction**
-    /// (`reader.inst_start_pc()`), enters the thunk, and returns
-    /// `Break::Force`.  When the thunk eventually returns, the VM will
-    /// **re-execute the entire opcode handler from the beginning**.
-    ///
-    /// # Invariants
-    ///
-    /// * **Do not call this method more than once in a single handler.**
-    ///   If you need to force multiple values, use a tuple type such as
-    ///   `(StrictValue, StrictValue)` so they are forced and popped in one
-    ///   atomic operation.  Calling `force_and_retry` twice (or more)
-    ///   means the handler will be re-run from the top after each retry;
-    ///   any stack modifications between the two calls would be duplicated
-    ///   and corrupt the stack layout.
-    ///
-    /// * The caller must ensure that the stack layout at the point of
-    ///   invocation is **identical** every time the handler is re-entered.
-    ///   In practice this means no pushes, pops, or local mutations may
-    ///   happen before the call, and the call must be the first thing
-    ///   that consumes the instruction's operand values.
-    ///
-    /// * The return value must be propagated with `?` so that
-    ///   `Break::Force` correctly unwinds to the dispatch loop.
-    #[inline(always)]
-    fn force_and_retry<T: Forced<'gc>>(
-        &mut self,
-        reader: &mut BytecodeReader<'_>,
-        mc: &Mutation<'gc>,
-    ) -> std::ops::ControlFlow<Break, T> {
-        self.force_and_retry_pc(reader, mc, reader.inst_start_pc())
-    }
-
-    /// Same as [`force_and_retry`](Self::force_and_retry) but allows
-    /// specifying a custom resume PC.
-    #[inline(always)]
-    fn force_and_retry_pc<T: Forced<'gc>>(
-        &mut self,
-        reader: &mut BytecodeReader<'_>,
-        mc: &Mutation<'gc>,
-        resume_pc: usize,
-    ) -> std::ops::ControlFlow<Break, T> {
-        T::force_and_check(self, reader, mc, 0, resume_pc)?;
-        std::ops::ControlFlow::Continue(T::pop_converted(self))
-    }
-
-    #[inline(always)]
-    #[allow(unused)]
-    fn force_slot(
-        &mut self,
-        depth: usize,
-        reader: &mut BytecodeReader<'_>,
-        mc: &Mutation<'gc>,
-    ) -> Step {
-        self.force_slot_to_pc(depth, reader, mc, reader.inst_start_pc())
-    }
-
-    #[inline(always)]
-    fn force_slot_to_pc(
-        &mut self,
-        depth: usize,
-        reader: &mut BytecodeReader<'_>,
-        mc: &Mutation<'gc>,
-        resume_pc: usize,
-    ) -> Step {
-        let Some(thunk) = self.peek(depth).as_gc::<Thunk>() else {
-            return Step::Continue(());
-        };
-        let mut state = thunk.borrow_mut(mc);
-        match *state {
-            ThunkState::Pending { ip, env } => {
-                *state = ThunkState::Blackhole;
-                self.call_stack.push(CallFrame {
-                    thunk: Some(thunk),
-                    pc: resume_pc,
-                    env: self.env,
-                });
-                self.env = env;
-                reader.set_pc(ip);
-                Step::Break(Break::Force)
-            }
-            ThunkState::Evaluated(v) => {
-                self.replace(depth, v.relax());
-                Step::Continue(())
-            }
-            ThunkState::Apply { func, arg } => {
-                self.call_stack.push(CallFrame {
-                    thunk: Some(thunk),
-                    pc: resume_pc,
-                    env: self.env,
-                });
-                self.push(func);
-                self.call(reader, mc, arg, resume_pc)
-            }
-            ThunkState::Blackhole => {
-                self.finish_err(Error::eval_error("infinite recursion encountered"))
-            }
-        }
-    }
-}
-
-impl<'gc> Machine<'gc> for Vm<'gc> {
-    #[inline(always)]
-    fn push(&mut self, val: Value<'gc>) {
-        self.push(val);
-    }
-
-    #[inline(always)]
-    fn pop(&mut self) -> Value<'gc> {
-        self.pop()
-    }
-
-    #[inline(always)]
-    fn peek(&self, depth: usize) -> Value<'gc> {
-        Vm::peek(self, depth)
-    }
-
-    #[inline(always)]
-    fn peek_forced(&self, depth: usize) -> StrictValue<'gc> {
-        Vm::peek_forced(self, depth)
-    }
-
-    #[inline(always)]
-    fn pop_forced(&mut self) -> StrictValue<'gc> {
-        self.pop_forced()
-    }
-
-    #[inline(always)]
-    fn replace(&mut self, depth: usize, val: Value<'gc>) {
-        self.replace(depth, val);
+    fn drop_n(&mut self, depth: usize) {
+        self.stack.truncate(self.stack.len() - depth);
     }
 
     #[inline(always)]
@@ -359,7 +204,41 @@ impl<'gc> Machine<'gc> for Vm<'gc> {
         mc: &Mutation<'gc>,
         resume_pc: usize,
     ) -> Step {
-        self.force_slot_to_pc(depth, reader, mc, resume_pc)
+        let Some(thunk) = self.peek(depth).downcast::<Thunk>() else {
+            return Step::Continue(());
+        };
+        let mut state = thunk.borrow_mut(mc);
+        match *state {
+            ThunkState::Pending { ip, env } => {
+                *state = ThunkState::Blackhole;
+                self.call_stack.push(CallFrame {
+                    thunk: Some(thunk),
+                    pc: resume_pc,
+                    env: self.env,
+                    depth: Some(depth),
+                });
+                self.env = env;
+                reader.set_pc(ip);
+                Step::Break(Break::Force)
+            }
+            ThunkState::Evaluated(v) => {
+                self.replace(depth, v.relax());
+                Step::Continue(())
+            }
+            ThunkState::Apply { func, arg } => {
+                self.call_stack.push(CallFrame {
+                    thunk: Some(thunk),
+                    pc: resume_pc,
+                    env: self.env,
+                    depth: Some(depth),
+                });
+                self.push(func);
+                self.call(reader, mc, arg, resume_pc)
+            }
+            ThunkState::Blackhole => {
+                self.finish_err(Error::eval_error("infinite recursion encountered"))
+            }
+        }
     }
 
     #[inline(always)]
@@ -370,7 +249,7 @@ impl<'gc> Machine<'gc> for Vm<'gc> {
         arg: Value<'gc>,
         resume_pc: usize,
     ) -> Step {
-        self.call(reader, mc, arg, resume_pc)
+        instructions::call(self, reader, mc, arg, resume_pc)
     }
 
     #[inline(always)]
@@ -409,22 +288,27 @@ impl<'gc> Machine<'gc> for Vm<'gc> {
     }
 
     #[inline(always)]
-    fn finish_ok(&mut self, val: fix_common::Value) -> Step {
-        self.finish_ok(val)
+    fn finish_ok(&mut self, val: fix_lang::Value) -> Step {
+        self.result = Some(Ok(val));
+        Step::Break(Break::Done)
     }
 
     #[inline(always)]
     fn finish_err(&mut self, err: Box<Error>) -> Step {
-        self.finish_err(err)
+        self.result = Some(Err(err));
+        Step::Break(Break::Done)
     }
 
     #[inline(always)]
     fn finish_type_err(&mut self, expected: NixType, got: NixType) -> Step {
-        self.finish_type_err(expected, got)
+        self.result = Some(Err(Error::eval_error(format!(
+            "expected {expected}, got {got}"
+        ))));
+        Step::Break(Break::Done)
     }
 
     #[inline(always)]
-    fn builtins(&self) -> Value<'gc> {
+    fn builtins(&self) -> Gc<'gc, AttrSet<'gc>> {
         self.builtins
     }
 
@@ -481,7 +365,7 @@ impl<'gc> Machine<'gc> for Vm<'gc> {
 
 enum Action {
     Continue { pc: usize },
-    Done(Result<fix_common::Value>),
+    Done(Result<fix_lang::Value>),
     LoadFile(PendingLoad),
 }
 
@@ -504,7 +388,7 @@ impl Vm<'_> {
         ctx: &mut C,
         ip: InstructionPtr,
         force_mode: ForceMode,
-    ) -> Result<fix_common::Value> {
+    ) -> Result<fix_lang::Value> {
         let (code, runtime) = ctx.split();
         let mut arena: Arena<Rootable![Vm<'_>]> = Arena::new(|mc| Vm::new(force_mode, mc, runtime));
         arena.metrics().set_pacing(Pacing {
@@ -582,6 +466,10 @@ impl<'gc> Vm<'gc> {
 
     #[inline(always)]
     #[cfg(not(feature = "tailcall"))]
+    #[expect(
+        clippy::unreachable,
+        reason = "Op::Illegal is a sentinel never emitted by codegen; reaching it is a codegen bug"
+    )]
     fn execute_batch(
         &mut self,
         bytecode: &[u8],
@@ -589,12 +477,15 @@ impl<'gc> Vm<'gc> {
         pc: usize,
         mc: &Mutation<'gc>,
     ) -> Action {
-        use fix_codegen::Op::*;
+        use fix_bytecode::Op::*;
+        use instructions::*;
 
         let mut reader = BytecodeReader::new(bytecode, pc);
         let mut fuel = Self::DEFAULT_FUEL_AMOUNT;
 
         loop {
+            use crate::instructions::op_dispatch_cont;
+
             if fuel == 0 {
                 return Action::Continue { pc: reader.pc() };
             }
@@ -603,75 +494,75 @@ impl<'gc> Vm<'gc> {
             let op = reader.read_op();
 
             let result = match op {
-                PushSmi => self.op_push_smi(&mut reader),
-                PushBigInt => self.op_push_bigint(&mut reader, mc),
-                PushFloat => self.op_push_float(&mut reader),
-                PushString => self.op_push_string(&mut reader),
-                PushNull => self.op_push_null(),
-                PushTrue => self.op_push_true(),
-                PushFalse => self.op_push_false(),
+                PushSmi => op_push_smi(self, &mut reader),
+                PushBigInt => op_push_bigint(self, &mut reader, mc),
+                PushFloat => op_push_float(self, &mut reader),
+                PushString => op_push_string(self, &mut reader),
+                PushNull => op_push_null(self),
+                PushTrue => op_push_true(self),
+                PushFalse => op_push_false(self),
 
-                LoadLocal => self.op_load_local(&mut reader),
-                LoadOuter => self.op_load_outer(&mut reader),
-                StoreLocal => self.op_store_local(&mut reader, mc),
-                AllocLocals => self.op_alloc_locals(&mut reader, mc),
+                LoadLocal => op_load_local(self, &mut reader),
+                LoadOuter => op_load_outer(self, &mut reader),
+                StoreLocal => op_store_local(self, &mut reader, mc),
+                AllocLocals => op_alloc_locals(self, &mut reader, mc),
 
-                MakeThunk => self.op_make_thunk(&mut reader, mc),
-                MakeClosure => self.op_make_closure(&mut reader, mc),
-                MakePatternClosure => self.op_make_pattern_closure(&mut reader, mc),
+                MakeThunk => op_make_thunk(self, &mut reader, mc),
+                MakeClosure => op_make_closure(self, &mut reader, mc),
+                MakePatternClosure => op_make_pattern_closure(self, &mut reader, mc),
 
-                Call => self.op_call(ctx, &mut reader, mc),
-                DispatchPrimOp => self.op_dispatch_primop(ctx, &mut reader, mc),
-                Return => self.op_return(ctx, &mut reader, mc),
+                Call => op_call(self, ctx, &mut reader, mc),
+                DispatchCont => op_dispatch_cont(self, ctx, &mut reader, mc),
+                Return => op_return(self, ctx, &mut reader, mc),
 
-                MakeAttrs => self.op_make_attrs(ctx, &mut reader, mc),
-                MakeEmptyAttrs => self.op_make_empty_attrs(),
-                SelectStatic => self.op_select_static(ctx, &mut reader, mc),
-                SelectDynamic => self.op_select_dynamic(ctx, &mut reader, mc),
-                HasAttrPathStatic => self.op_has_attr_path_static(ctx, &mut reader, mc),
-                HasAttrPathDynamic => self.op_has_attr_path_dynamic(ctx, &mut reader, mc),
-                HasAttrStatic => self.op_has_attr_static(&mut reader, mc),
-                HasAttrDynamic => self.op_has_attr_dynamic(ctx, &mut reader, mc),
-                HasAttrResolve => self.op_has_attr_resolve(),
-                JumpIfSelectFailed => self.op_jump_if_select_failed(&mut reader),
-                JumpIfSelectSucceeded => self.op_jump_if_select_succeeded(&mut reader),
+                MakeAttrs => op_make_attrs(self, ctx, &mut reader, mc),
+                MakeEmptyAttrs => op_make_empty_attrs(self),
+                SelectStatic => op_select_static(self, ctx, &mut reader, mc),
+                SelectDynamic => op_select_dynamic(self, ctx, &mut reader, mc),
+                HasAttrPathStatic => op_has_attr_path_static(self, ctx, &mut reader, mc),
+                HasAttrPathDynamic => op_has_attr_path_dynamic(self, ctx, &mut reader, mc),
+                HasAttrStatic => op_has_attr_static(self, &mut reader, mc),
+                HasAttrDynamic => op_has_attr_dynamic(self, ctx, &mut reader, mc),
+                HasAttrResolve => op_has_attr_resolve(self),
+                JumpIfSelectFailed => op_jump_if_select_failed(self, &mut reader),
+                JumpIfSelectSucceeded => op_jump_if_select_succeeded(self, &mut reader),
 
-                MakeList => self.op_make_list(ctx, &mut reader, mc),
-                MakeEmptyList => self.op_make_empty_list(),
+                MakeList => op_make_list(self, ctx, &mut reader, mc),
+                MakeEmptyList => op_make_empty_list(self),
 
-                OpAdd => self.op_add(ctx, &mut reader, mc),
-                OpSub => self.op_sub(&mut reader, mc),
-                OpMul => self.op_mul(&mut reader, mc),
-                OpDiv => self.op_div(&mut reader, mc),
-                OpEq => self.op_eq(ctx, &mut reader, mc),
-                OpNeq => self.op_neq(ctx, &mut reader, mc),
-                OpLt => self.op_lt(ctx, &mut reader, mc),
-                OpGt => self.op_gt(ctx, &mut reader, mc),
-                OpLeq => self.op_leq(ctx, &mut reader, mc),
-                OpGeq => self.op_geq(ctx, &mut reader, mc),
-                OpConcat => self.op_concat(&mut reader, mc),
-                OpUpdate => self.op_update(&mut reader, mc),
+                OpAdd => op_add(self, ctx, &mut reader, mc),
+                OpSub => op_sub(self, &mut reader, mc),
+                OpMul => op_mul(self, &mut reader, mc),
+                OpDiv => op_div(self, &mut reader, mc),
+                OpEq => op_eq(self, ctx, &mut reader, mc),
+                OpNeq => op_neq(self, ctx, &mut reader, mc),
+                OpLt => op_lt(self, ctx, &mut reader, mc),
+                OpGt => op_gt(self, ctx, &mut reader, mc),
+                OpLeq => op_leq(self, ctx, &mut reader, mc),
+                OpGeq => op_geq(self, ctx, &mut reader, mc),
+                OpConcat => op_concat(self, &mut reader, mc),
+                OpUpdate => op_update(self, &mut reader, mc),
 
-                OpNeg => self.op_neg(&mut reader, mc),
-                OpNot => self.op_not(&mut reader, mc),
+                OpNeg => op_neg(self, &mut reader, mc),
+                OpNot => op_not(self, &mut reader, mc),
 
-                JumpIfFalse => self.op_jump_if_false(&mut reader, mc),
-                JumpIfTrue => self.op_jump_if_true(&mut reader, mc),
-                Jump => self.op_jump(&mut reader),
+                JumpIfFalse => op_jump_if_false(self, &mut reader, mc),
+                JumpIfTrue => op_jump_if_true(self, &mut reader, mc),
+                Jump => op_jump(self, &mut reader),
 
-                ConcatStrings => self.op_concat_strings(ctx, &mut reader, mc),
-                CoerceToString => self.op_coerce_to_string(&mut reader, mc),
-                ResolvePath => self.op_resolve_path(ctx, &mut reader, mc),
+                ConcatStrings => op_concat_strings(self, ctx, &mut reader, mc),
+                CoerceToString => op_coerce_to_string(self, &mut reader, mc),
+                ResolvePath => op_resolve_path(self, ctx, &mut reader, mc),
 
-                Assert => self.op_assert(ctx, &mut reader, mc),
+                Assert => op_assert(self, ctx, &mut reader, mc),
 
-                LookupWith => self.op_lookup_with(ctx, &mut reader, mc),
+                LookupWith => op_lookup_with(self, ctx, &mut reader, mc),
 
-                LoadBuiltins => self.op_load_builtins(),
-                LoadBuiltin => self.op_load_builtin(&mut reader),
+                LoadBuiltins => op_load_builtins(self),
+                LoadBuiltin => op_load_builtin(self, &mut reader),
 
-                LoadReplBinding => self.op_load_repl_binding(&mut reader),
-                LoadScopedBinding => self.op_load_scoped_binding(ctx, &mut reader, mc),
+                LoadReplBinding => op_load_repl_binding(self, &mut reader),
+                LoadScopedBinding => op_load_scoped_binding(self, ctx, &mut reader, mc),
 
                 Illegal => unreachable!(),
             };

fix-vm/src/macro_support.rs

@@ -0,0 +1,36 @@
+//! Single macro-facing path for the `#[primop]` support surface: the traits
+//! generated code type-checks through (defined in `fix_runtime`, where the
+//! impl sets are coherent) and the stub trio that keeps un-expanded primop
+//! sources resolving in tooling.
+
+use std::future::Future;
+
+pub use fix_runtime::{CalleeReady, ForceTarget, UnwrapSlot};
+use fix_runtime::{Slot, Value};
+
+macro_rules! type_hint {
+    () => {
+        if false {
+            return async {
+                unreachable!();
+            };
+        }
+    };
+}
+
+#[expect(clippy::panic, reason = "deliberately panic when the stub is called")]
+pub fn force<T>(_: Slot<Value<'_>>) -> impl Future<Output = Slot<T>> {
+    type_hint!();
+    panic!("stub `force` called at runtime")
+}
+
+#[expect(clippy::panic, reason = "deliberately panic when the stub is called")]
+pub fn call<T, A, R>(_: &T, _: A) -> impl Future<Output = R> {
+    type_hint!();
+    panic!("stub `call` called at runtime")
+}
+
+#[expect(clippy::panic, reason = "deliberately panic when the stub is called")]
+pub fn spill<T>(_: T) -> Slot<T> {
+    panic!("stub `spill` called at runtime")
+}

fix-vm/src/primops/context.rs

@@ -2,16 +2,16 @@
 //! `builtins.unsafeDiscardStringContext`,
 //! `builtins.unsafeDiscardOutputDependency`.
 //!
-//! See `fix-abstract-vm/src/string_context.rs` for the
+//! See `fix-runtime/src/string_context.rs` for the
 //! `StringContextElem` type.
 
-use fix_abstract_vm::{
+use fix_bytecode::Continuation;
+use fix_error::Error;
+use fix_lang::StringId;
+use fix_runtime::{
     AttrSet, BytecodeReader, List as VmList, Machine, MachineExt, NixString, NixType, Step,
     StrictValue, StringContext, StringContextElem, Value, VmRuntimeCtx, VmRuntimeCtxExt,
 };
-use fix_builtins::PrimOpPhase;
-use fix_common::StringId;
-use fix_error::Error;
 use gc_arena::{Gc, Mutation};
 use smallvec::SmallVec;
 
@@ -22,11 +22,11 @@ pub fn has_context<'gc, M: Machine<'gc>>(
     mc: &Mutation<'gc>,
 ) -> Step {
     let val = m.force_and_retry::<StrictValue>(reader, mc)?;
-    if !val.is::<StringId>() && val.as_gc::<NixString>().is_none() {
+    if !val.is::<StringId>() && val.downcast::<NixString>().is_none() {
         return m.finish_type_err(NixType::String, val.ty());
     }
     let has_ctx = !ctx.get_string_context(val).is_empty();
-    m.return_from_primop(Value::new_inline(has_ctx), reader)
+    m.return_from_primop(Value::new(has_ctx), reader)
 }
 
 pub fn unsafe_discard_string_context<'gc, M: Machine<'gc>>(
@@ -36,14 +36,14 @@ pub fn unsafe_discard_string_context<'gc, M: Machine<'gc>>(
     mc: &Mutation<'gc>,
 ) -> Step {
     let val = m.force_and_retry::<StrictValue>(reader, mc)?;
-    if let Some(sid) = val.as_inline::<StringId>() {
-        return m.return_from_primop(Value::new_inline(sid), reader);
+    if let Some(sid) = val.downcast::<StringId>() {
+        return m.return_from_primop(Value::new(sid), reader);
     }
-    let Some(ns) = val.as_gc::<NixString>() else {
+    let Some(ns) = val.downcast::<NixString>() else {
         return m.finish_type_err(NixType::String, val.ty());
     };
     let sid = ctx.intern_string(ns.as_str());
-    m.return_from_primop(Value::new_inline(sid), reader)
+    m.return_from_primop(Value::new(sid), reader)
 }
 
 pub fn unsafe_discard_output_dependency<'gc, M: Machine<'gc>>(
@@ -53,15 +53,15 @@ pub fn unsafe_discard_output_dependency<'gc, M: Machine<'gc>>(
     mc: &Mutation<'gc>,
 ) -> Step {
     let val = m.force_and_retry::<StrictValue>(reader, mc)?;
-    if let Some(sid) = val.as_inline::<StringId>() {
-        return m.return_from_primop(Value::new_inline(sid), reader);
+    if let Some(sid) = val.downcast::<StringId>() {
+        return m.return_from_primop(Value::new(sid), reader);
     }
-    let Some(ns) = val.as_gc::<NixString>() else {
+    let Some(ns) = val.downcast::<NixString>() else {
         return m.finish_type_err(NixType::String, val.ty());
     };
     if ns.context().is_empty() {
         let sid = ctx.intern_string(ns.as_str());
-        return m.return_from_primop(Value::new_inline(sid), reader);
+        return m.return_from_primop(Value::new(sid), reader);
     }
 
     let mut new_ctx = StringContext::new();
@@ -77,7 +77,7 @@ pub fn unsafe_discard_output_dependency<'gc, M: Machine<'gc>>(
 
     let s: Box<str> = ns.as_str().into();
     let new_ns = Gc::new(mc, NixString::with_context(s, new_ctx));
-    m.return_from_primop(Value::new_gc(new_ns), reader)
+    m.return_from_primop(Value::new(new_ns), reader)
 }
 
 pub fn get_context<'gc, M: Machine<'gc>>(
@@ -87,7 +87,7 @@ pub fn get_context<'gc, M: Machine<'gc>>(
     mc: &Mutation<'gc>,
 ) -> Step {
     let val = m.force_and_retry::<StrictValue>(reader, mc)?;
-    if !val.is::<StringId>() && val.as_gc::<NixString>().is_none() {
+    if !val.is::<StringId>() && val.downcast::<NixString>().is_none() {
         return m.finish_type_err(NixType::String, val.ty());
     }
     let elems = ctx.get_string_context(val);
@@ -135,29 +135,29 @@ pub fn get_context<'gc, M: Machine<'gc>>(
 
         let mut sub: SmallVec<[(StringId, Value<'gc>); 4]> = SmallVec::new();
         if info.all_outputs {
-            sub.push((ctx.intern_string("allOutputs"), Value::new_inline(true)));
+            sub.push((ctx.intern_string("allOutputs"), Value::new(true)));
         }
         if !info.outputs.is_empty() {
             let items: smallvec::SmallVec<[Value<'gc>; 4]> = info
                 .outputs
                 .iter()
-                .map(|o| Value::new_inline(ctx.intern_string(o)))
+                .map(|o| Value::new(ctx.intern_string(o)))
                 .collect();
             let list = VmList::new(mc, items);
-            sub.push((ctx.intern_string("outputs"), Value::new_gc(list)));
+            sub.push((ctx.intern_string("outputs"), Value::new(list)));
         }
         if info.path {
-            sub.push((ctx.intern_string("path"), Value::new_inline(true)));
+            sub.push((ctx.intern_string("path"), Value::new(true)));
         }
         sub.sort_by_key(|(k, _)| *k);
         let sub_attrs = Gc::new(mc, AttrSet::from_sorted_unchecked(sub));
 
-        outer_entries.push((ctx.intern_string(&path), Value::new_gc(sub_attrs)));
+        outer_entries.push((ctx.intern_string(&path), Value::new(sub_attrs)));
     }
     outer_entries.sort_by_key(|(k, _)| *k);
 
     let outer = Gc::new(mc, AttrSet::from_sorted_unchecked(outer_entries));
-    m.return_from_primop(Value::new_gc(outer), reader)
+    m.return_from_primop(Value::new(outer), reader)
 }
 
 /// appendContext :: String -> AttrSet -> String
@@ -192,24 +192,33 @@ pub fn append_context<'gc, M: Machine<'gc>>(
     let acc = Gc::new(mc, NixString::with_context("", initial_ctx));
 
     m.push(str_val.relax());
-    m.push(Value::new_gc(attrs));
-    m.push(Value::new_inline(0i32));
-    m.push(Value::new_gc(acc));
+    m.push(Value::new(attrs));
+    m.push(Value::new(0i32));
+    m.push(Value::new(acc));
 
-    reader.set_pc(PrimOpPhase::AppendContextLoop.ip() as usize);
+    reader.set_pc(Continuation::PAppendContextLoop.ip() as usize);
     Step::Continue(())
 }
 
+#[expect(
+    clippy::indexing_slicing,
+    clippy::cast_sign_loss,
+    reason = "idx is a non-negative loop counter guarded by `idx as usize >= attrs.entries.len()`, so it indexes attrs.entries in bounds"
+)]
 pub fn append_context_loop<'gc, M: Machine<'gc>>(
     m: &mut M,
     ctx: &mut impl VmRuntimeCtx,
     reader: &mut BytecodeReader<'_>,
     mc: &Mutation<'gc>,
 ) -> Step {
-    #[allow(clippy::unwrap_used)]
-    let idx = m.peek(1).as_inline::<i32>().unwrap();
-    #[allow(clippy::unwrap_used)]
-    let attrs = m.peek_forced(2).as_gc::<AttrSet>().unwrap();
+    let idx = m
+        .peek(1)
+        .downcast::<i32>()
+        .expect("stack slot must be an integer");
+    let attrs = m
+        .peek_forced(2)
+        .downcast::<AttrSet>()
+        .expect("stack slot must be an attrset");
 
     if idx as usize >= attrs.entries.len() {
         return append_context_finalize(m, ctx, reader, mc);
@@ -221,12 +230,17 @@ pub fn append_context_loop<'gc, M: Machine<'gc>>(
         0,
         reader,
         mc,
-        PrimOpPhase::AppendContextEntryForced.ip() as usize,
+        Continuation::PAppendContextEntryForced.ip() as usize,
     )?;
-    reader.set_pc(PrimOpPhase::AppendContextEntryForced.ip() as usize);
+    reader.set_pc(Continuation::PAppendContextEntryForced.ip() as usize);
     Step::Continue(())
 }
 
+#[expect(
+    clippy::indexing_slicing,
+    clippy::cast_sign_loss,
+    reason = "idx is the same non-negative outer-loop counter, in range for outer.entries validated by append_context_loop"
+)]
 pub fn append_context_entry_forced<'gc, M: Machine<'gc>>(
     m: &mut M,
     ctx: &mut impl VmRuntimeCtx,
@@ -238,14 +252,18 @@ pub fn append_context_entry_forced<'gc, M: Machine<'gc>>(
     // Evaluated value into the slot.
     m.force_slot(0, reader, mc)?;
     let entry_val = m.peek_forced(0);
-    let Some(entry_attrs) = entry_val.as_gc::<AttrSet>() else {
+    let Some(entry_attrs) = entry_val.downcast::<AttrSet>() else {
         return m.finish_type_err(NixType::AttrSet, entry_val.ty());
     };
 
-    #[allow(clippy::unwrap_used)]
-    let idx = m.peek(2).as_inline::<i32>().unwrap();
-    #[allow(clippy::unwrap_used)]
-    let outer = m.peek_forced(3).as_gc::<AttrSet>().unwrap();
+    let idx = m
+        .peek(2)
+        .downcast::<i32>()
+        .expect("stack slot must be an integer");
+    let outer = m
+        .peek_forced(3)
+        .downcast::<AttrSet>()
+        .expect("stack slot must be an attrset");
     let path_key = outer.entries[idx as usize].0;
     let path_str_owned: Box<str> = ctx.resolve_string(path_key).into();
     if !path_str_owned.starts_with("/nix/store/") {
@@ -262,12 +280,14 @@ pub fn append_context_entry_forced<'gc, M: Machine<'gc>>(
     let all_outputs_id = ctx.intern_string("allOutputs");
     let outputs_id = ctx.intern_string("outputs");
 
-    #[allow(clippy::unwrap_used)]
-    let acc_gc = m.peek(1).as_gc::<NixString>().unwrap();
+    let acc_gc = m
+        .peek(1)
+        .downcast::<NixString>()
+        .expect("stack slot must be a string");
     let mut new_acc: StringContext = acc_gc.context().iter().cloned().collect();
 
     if let Some(v) = entry_attrs.lookup(path_id)
-        && v.as_inline::<bool>() == Some(true)
+        && v.downcast::<bool>() == Some(true)
     {
         new_acc.insert(StringContextElem::Opaque {
             path: path_str_owned.clone(),
@@ -275,7 +295,7 @@ pub fn append_context_entry_forced<'gc, M: Machine<'gc>>(
     }
 
     if let Some(v) = entry_attrs.lookup(all_outputs_id)
-        && v.as_inline::<bool>() == Some(true)
+        && v.downcast::<bool>() == Some(true)
     {
         if !path_str_owned.ends_with(".drv") {
             return m.finish_err(Error::eval_error(format!(
@@ -288,7 +308,7 @@ pub fn append_context_entry_forced<'gc, M: Machine<'gc>>(
     }
 
     let new_acc_gc = Gc::new(mc, NixString::with_context("", new_acc));
-    m.replace(1, Value::new_gc(new_acc_gc));
+    m.replace(1, Value::new(new_acc_gc));
 
     if let Some(outputs_val) = entry_attrs.lookup(outputs_id) {
         m.replace(0, outputs_val);
@@ -296,17 +316,19 @@ pub fn append_context_entry_forced<'gc, M: Machine<'gc>>(
             0,
             reader,
             mc,
-            PrimOpPhase::AppendContextOutputsForced.ip() as usize,
+            Continuation::PAppendContextOutputsForced.ip() as usize,
         )?;
-        reader.set_pc(PrimOpPhase::AppendContextOutputsForced.ip() as usize);
+        reader.set_pc(Continuation::PAppendContextOutputsForced.ip() as usize);
         return Step::Continue(());
     }
 
-    let _ = m.pop();
-    #[allow(clippy::unwrap_used)]
-    let idx_back = m.peek(1).as_inline::<i32>().unwrap();
-    m.replace(1, Value::new_inline(idx_back + 1));
-    reader.set_pc(PrimOpPhase::AppendContextLoop.ip() as usize);
+    m.drop_n(1);
+    let idx_back = m
+        .peek(1)
+        .downcast::<i32>()
+        .expect("stack slot must be an integer");
+    m.replace(1, Value::new(idx_back + 1));
+    reader.set_pc(Continuation::PAppendContextLoop.ip() as usize);
     Step::Continue(())
 }
 
@@ -318,44 +340,56 @@ pub fn append_context_outputs_forced<'gc, M: Machine<'gc>>(
 ) -> Step {
     m.force_slot(0, reader, mc)?;
     let list_val = m.peek_forced(0);
-    let Some(list) = list_val.as_gc::<VmList>() else {
+    let Some(list) = list_val.downcast::<VmList>() else {
         return m.finish_type_err(NixType::List, list_val.ty());
     };
     if list.inner.borrow().is_empty() {
         // Stack: [strVal, attrs, idx, acc, list] -> drop list, bump idx.
-        let _ = m.pop();
-        #[allow(clippy::unwrap_used)]
-        let idx_back = m.peek(1).as_inline::<i32>().unwrap();
-        m.replace(1, Value::new_inline(idx_back + 1));
-        reader.set_pc(PrimOpPhase::AppendContextLoop.ip() as usize);
+        m.drop_n(1);
+        let idx_back = m
+            .peek(1)
+            .downcast::<i32>()
+            .expect("stack slot must be an integer");
+        m.replace(1, Value::new(idx_back + 1));
+        reader.set_pc(Continuation::PAppendContextLoop.ip() as usize);
         return Step::Continue(());
     }
 
-    m.push(Value::new_inline(0i32));
-    reader.set_pc(PrimOpPhase::AppendContextOutputElementLoop.ip() as usize);
+    m.push(Value::new(0i32));
+    reader.set_pc(Continuation::PAppendContextOutputElementLoop.ip() as usize);
     Step::Continue(())
 }
 
+#[expect(
+    clippy::indexing_slicing,
+    clippy::cast_sign_loss,
+    reason = "oidx is a non-negative loop counter guarded by `oidx as usize >= len`, so it indexes the list in bounds"
+)]
 pub fn append_context_output_element_loop<'gc, M: Machine<'gc>>(
     m: &mut M,
     _ctx: &mut impl VmRuntimeCtx,
     reader: &mut BytecodeReader<'_>,
     mc: &Mutation<'gc>,
 ) -> Step {
-    #[allow(clippy::unwrap_used)]
-    let oidx = m.peek(0).as_inline::<i32>().unwrap();
-    #[allow(clippy::unwrap_used)]
-    let list = m.peek_forced(1).as_gc::<VmList>().unwrap();
+    let oidx = m
+        .peek(0)
+        .downcast::<i32>()
+        .expect("stack slot must be an integer");
+    let list = m
+        .peek_forced(1)
+        .downcast::<VmList>()
+        .expect("stack slot must be a list");
     let len = list.inner.borrow().len();
     if oidx as usize >= len {
         // Stack: [strVal, attrs, idx, acc, list, oidx] -> drop oidx & list,
         // bump idx in place.
-        let _ = m.pop();
-        let _ = m.pop();
-        #[allow(clippy::unwrap_used)]
-        let idx_back = m.peek(1).as_inline::<i32>().unwrap();
-        m.replace(1, Value::new_inline(idx_back + 1));
-        reader.set_pc(PrimOpPhase::AppendContextLoop.ip() as usize);
+        m.drop_n(2);
+        let idx_back = m
+            .peek(1)
+            .downcast::<i32>()
+            .expect("stack slot must be an integer");
+        m.replace(1, Value::new(idx_back + 1));
+        reader.set_pc(Continuation::PAppendContextLoop.ip() as usize);
         return Step::Continue(());
     }
 
@@ -365,12 +399,17 @@ pub fn append_context_output_element_loop<'gc, M: Machine<'gc>>(
         0,
         reader,
         mc,
-        PrimOpPhase::AppendContextOutputElementForced.ip() as usize,
+        Continuation::PAppendContextOutputElementForced.ip() as usize,
     )?;
-    reader.set_pc(PrimOpPhase::AppendContextOutputElementForced.ip() as usize);
+    reader.set_pc(Continuation::PAppendContextOutputElementForced.ip() as usize);
     Step::Continue(())
 }
 
+#[expect(
+    clippy::indexing_slicing,
+    clippy::cast_sign_loss,
+    reason = "idx is the non-negative outer-loop counter, in range for outer.entries validated by append_context_loop"
+)]
 pub fn append_context_output_element_forced<'gc, M: Machine<'gc>>(
     m: &mut M,
     ctx: &mut impl VmRuntimeCtx,
@@ -384,10 +423,14 @@ pub fn append_context_output_element_forced<'gc, M: Machine<'gc>>(
     };
     let output_name: Box<str> = output_name.into();
 
-    #[allow(clippy::unwrap_used)]
-    let idx = m.peek(4).as_inline::<i32>().unwrap();
-    #[allow(clippy::unwrap_used)]
-    let outer = m.peek_forced(5).as_gc::<AttrSet>().unwrap();
+    let idx = m
+        .peek(4)
+        .downcast::<i32>()
+        .expect("stack slot must be an integer");
+    let outer = m
+        .peek_forced(5)
+        .downcast::<AttrSet>()
+        .expect("stack slot must be an attrset");
     let path_key = outer.entries[idx as usize].0;
     let path_str: Box<str> = ctx.resolve_string(path_key).into();
     if !path_str.ends_with(".drv") {
@@ -396,26 +439,34 @@ pub fn append_context_output_element_forced<'gc, M: Machine<'gc>>(
         )));
     }
 
-    #[allow(clippy::unwrap_used)]
-    let acc_gc = m.peek(3).as_gc::<NixString>().unwrap();
+    let acc_gc = m
+        .peek(3)
+        .downcast::<NixString>()
+        .expect("stack slot must be a string");
     let mut new_acc: StringContext = acc_gc.context().iter().cloned().collect();
     new_acc.insert(StringContextElem::Built {
         drv_path: path_str,
         output: output_name,
     });
     let new_acc_gc = Gc::new(mc, NixString::with_context("", new_acc));
-    m.replace(3, Value::new_gc(new_acc_gc));
+    m.replace(3, Value::new(new_acc_gc));
 
     // Stack: [strVal, attrs, idx, acc, list, oidx, outElem] -> drop outElem,
     // bump oidx in place.
-    let _ = m.pop();
-    #[allow(clippy::unwrap_used)]
-    let oidx = m.peek(0).as_inline::<i32>().unwrap();
-    m.replace(0, Value::new_inline(oidx + 1));
-    reader.set_pc(PrimOpPhase::AppendContextOutputElementLoop.ip() as usize);
+    m.drop_n(1);
+    let oidx = m
+        .peek(0)
+        .downcast::<i32>()
+        .expect("stack slot must be an integer");
+    m.replace(0, Value::new(oidx + 1));
+    reader.set_pc(Continuation::PAppendContextOutputElementLoop.ip() as usize);
     Step::Continue(())
 }
 
+#[expect(
+    clippy::panic,
+    reason = "strVal was forced to WHNF at appendContext entry, so restrict() can never observe a thunk here"
+)]
 fn append_context_finalize<'gc, M: Machine<'gc>>(
     m: &mut M,
     ctx: &mut impl VmRuntimeCtx,
@@ -423,10 +474,11 @@ fn append_context_finalize<'gc, M: Machine<'gc>>(
     mc: &Mutation<'gc>,
 ) -> Step {
     // Stack: [strVal, attrs, idx, acc]
-    #[allow(clippy::unwrap_used)]
-    let acc_gc = m.pop().as_gc::<NixString>().unwrap();
-    let _ = m.pop(); // idx
-    let _ = m.pop(); // attrs
+    let acc_gc = m
+        .pop()
+        .downcast::<NixString>()
+        .expect("stack slot must be a string");
+    m.drop_n(2);
     let str_val_raw = m.pop();
 
     // The strVal was already forced at entry; restrict() is infallible here.
@@ -438,10 +490,10 @@ fn append_context_finalize<'gc, M: Machine<'gc>>(
     let context: StringContext = acc_gc.context().iter().cloned().collect();
     let result = if context.is_empty() {
         let sid = ctx.intern_string(s_str);
-        Value::new_inline(sid)
+        Value::new(sid)
     } else {
         let ns = Gc::new(mc, NixString::with_context(s_str, context));
-        Value::new_gc(ns)
+        Value::new(ns)
     };
     m.return_from_primop(result, reader)
 }

fix-vm/src/primops/control.rs

@@ -1,22 +1,89 @@
-use fix_abstract_vm::{
-    AttrSet, BytecodeReader, Closure, Env, List, Machine, MachineExt, Step, StrictValue, Value,
-    VmRuntimeCtx, VmRuntimeCtxExt,
+use fix_bytecode::Continuation;
+use fix_error::{Error, Result};
+use fix_macros::handler;
+use fix_runtime::{
+    AttrSet, BytecodeReader, Closure, Env, List, Machine, MachineExt, Slot, Step, StrictValue,
+    Value, VmRuntimeCtx, VmRuntimeCtxExt,
 };
-use fix_builtins::PrimOpPhase;
-use fix_error::Error;
 use gc_arena::{Gc, Mutation, RefLock};
 use smallvec::SmallVec;
 
-pub fn seq<'gc, M: Machine<'gc>>(
-    m: &mut M,
-    reader: &mut BytecodeReader<'_>,
+use crate::primops::stubs::*;
+
+#[handler(name = PSeq)]
+fn seq<'gc>(mc: &Mutation<'gc>, e1: Slot<Value<'gc>>, e2: Slot<Value<'gc>>) -> Result<Value<'gc>> {
+    let _e1: Slot<StrictValue<'gc>> = force(e1).await?;
+    Ok(e2.get())
+}
+
+#[handler(name = PDeepSeq)]
+fn deep_seq<'gc>(
     mc: &Mutation<'gc>,
-) -> Step {
-    // stack: [e1, e2] - force e1, return e2
-    m.force_slot(1, reader, mc)?;
-    let e2 = m.pop();
-    let _ = m.pop();
-    m.return_from_primop(e2, reader)
+    e1: Slot<Value<'gc>>,
+    e2: Slot<Value<'gc>>,
+) -> Result<Value<'gc>> {
+    let e1: Slot<StrictValue<'gc>> = force(e1).await?;
+    if collect_children(e1.get()).is_empty() {
+        return Ok(e2.get());
+    }
+    let seen: Slot<List<'gc>> = spill(Gc::new(mc, List::default()));
+    let worklist: Slot<List<'gc>> = spill(List::new(mc, collect_children(e1.get())));
+    let count: Slot<i32> = spill(worklist.get().inner.borrow().len() as i32);
+    loop {
+        if count.get() == 0 {
+            return Ok(e2.get());
+        }
+        let item = worklist
+            .get()
+            .unlock(mc)
+            .borrow_mut()
+            .pop()
+            .expect("worklist is non-empty while count > 0");
+        count.set(count.get() - 1);
+        let item: Slot<StrictValue<'gc>> = force(item).await?;
+        let added = push_children(mc, seen.get(), worklist.get(), item);
+        count.set(count.get() + added);
+    }
+}
+
+fn collect_children<'gc>(val: StrictValue<'gc>) -> SmallVec<[Value<'gc>; 4]> {
+    if let Some(attrs) = val.downcast::<AttrSet<'gc>>() {
+        attrs.entries.iter().map(|&(_, v)| v).collect()
+    } else if let Some(list) = val.downcast::<List<'gc>>() {
+        list.inner.borrow().iter().copied().collect()
+    } else {
+        SmallVec::new()
+    }
+}
+
+fn push_children<'gc>(
+    mc: &Mutation<'gc>,
+    seen: Gc<'gc, List<'gc>>,
+    worklist: Gc<'gc, List<'gc>>,
+    item: StrictValue<'gc>,
+) -> i32 {
+    let mut added = 0i32;
+    if let Some(attrs) = item.downcast::<AttrSet<'gc>>()
+        && !is_value_in_seen(seen, item.relax())
+    {
+        add_value_to_seen(seen, mc, item.relax());
+        let mut wl = worklist.unlock(mc).borrow_mut();
+        for &(_, v) in attrs.entries.iter() {
+            wl.push(v);
+        }
+        added = attrs.entries.len() as i32;
+    } else if let Some(list) = item.downcast::<List<'gc>>()
+        && !is_value_in_seen(seen, item.relax())
+    {
+        add_value_to_seen(seen, mc, item.relax());
+        let inner = list.inner.borrow();
+        let mut wl = worklist.unlock(mc).borrow_mut();
+        for &v in inner.iter() {
+            wl.push(v);
+        }
+        added = inner.len() as i32;
+    }
+    added
 }
 
 pub fn abort<'gc, M: Machine<'gc>>(
@@ -34,133 +101,6 @@ pub fn abort<'gc, M: Machine<'gc>>(
     )))
 }
 
-pub fn deep_seq_force_top<'gc, M: Machine<'gc>>(
-    m: &mut M,
-    reader: &mut BytecodeReader<'_>,
-    mc: &Mutation<'gc>,
-) -> Step {
-    // stack: [e1, e2] - force e1, return e2
-    m.force_slot(1, reader, mc)?;
-
-    let e1 = m.peek_forced(1);
-
-    let children: SmallVec<_> = if let Some(attrs) = e1.as_gc::<AttrSet>() {
-        let attrs = &attrs.entries;
-        if attrs.is_empty() {
-            SmallVec::new()
-        } else {
-            attrs.iter().map(|&(_, v)| v).collect()
-        }
-    } else if let Some(list) = e1.as_gc::<List<'gc>>() {
-        let inner = list.inner.borrow();
-        if inner.is_empty() {
-            SmallVec::new()
-        } else {
-            inner.iter().copied().collect()
-        }
-    } else {
-        SmallVec::new()
-    };
-
-    if children.is_empty() {
-        let e2 = m.pop();
-        let _ = m.pop();
-        return m.return_from_primop(e2, reader);
-    }
-
-    let count = children.len() as i32;
-    let seen: Gc<'gc, List<'gc>> = Gc::new(mc, List::default());
-    let worklist: Gc<'gc, List<'gc>> = List::new(mc, children);
-
-    let e2 = m.pop();
-    let _ = m.pop();
-    m.push(e2);
-    m.push(Value::new_gc(seen));
-    m.push(Value::new_gc(worklist));
-    m.push(Value::new_inline(count));
-    reader.set_pc(PrimOpPhase::DeepSeqPush.ip() as usize);
-    Step::Continue(())
-}
-
-pub fn deep_seq_push<'gc, M: Machine<'gc>>(
-    m: &mut M,
-    reader: &mut BytecodeReader<'_>,
-    mc: &Mutation<'gc>,
-) -> Step {
-    // stack: [e2, seen, worklist, counter]
-    #[allow(clippy::unwrap_used)]
-    let counter = m.peek(0).as_inline::<i32>().unwrap();
-    if counter == 0 {
-        let _ = m.pop(); // counter
-        let _ = m.pop(); // worklist
-        let _ = m.pop(); // seen
-        let val = m.pop();
-        return m.return_from_primop(val, reader);
-    }
-
-    #[allow(clippy::unwrap_used)]
-    let worklist = m.peek_forced(1).as_gc::<List<'gc>>().unwrap();
-    #[allow(clippy::unwrap_used)]
-    let item = worklist.unlock(mc).borrow_mut().pop().unwrap();
-    m.replace(0, Value::new_inline(counter - 1));
-    m.push(item);
-
-    // force item at TOS, resume at DeepSeqLoop after force
-    m.force_slot_to_pc(0, reader, mc, PrimOpPhase::DeepSeqLoop.ip() as usize)?;
-    reader.set_pc(PrimOpPhase::DeepSeqLoop.ip() as usize);
-    Step::Continue(())
-}
-
-pub fn deep_seq_loop<'gc, M: Machine<'gc>>(
-    m: &mut M,
-    reader: &mut BytecodeReader<'_>,
-    mc: &Mutation<'gc>,
-) -> Step {
-    // stack after pop: [e2, seen, worklist, counter]
-    let item = m.pop();
-    #[allow(clippy::unwrap_used)]
-    let counter = m.peek(0).as_inline::<i32>().unwrap();
-
-    let mut added: usize = 0;
-    if let Some(attrs) = item.as_gc::<AttrSet>() {
-        let attrs = &attrs.entries;
-        #[allow(clippy::unwrap_used)]
-        let seen = m.peek_forced(2).as_gc::<List<'gc>>().unwrap();
-        if !is_value_in_seen(seen, item) {
-            add_value_to_seen(seen, mc, item);
-            #[allow(clippy::unwrap_used)]
-            let worklist = m.peek_forced(1).as_gc::<List<'gc>>().unwrap();
-            {
-                let mut wl = worklist.unlock(mc).borrow_mut();
-                for &(_, v) in attrs.iter() {
-                    wl.push(v);
-                }
-                added = attrs.len();
-            }
-        }
-    } else if let Some(list) = item.as_gc::<List<'gc>>() {
-        #[allow(clippy::unwrap_used)]
-        let seen = m.peek_forced(2).as_gc::<List<'gc>>().unwrap();
-        if !is_value_in_seen(seen, item) {
-            add_value_to_seen(seen, mc, item);
-            #[allow(clippy::unwrap_used)]
-            let worklist = m.peek_forced(1).as_gc::<List<'gc>>().unwrap();
-            {
-                let inner = list.inner.borrow();
-                let mut wl = worklist.unlock(mc).borrow_mut();
-                for &v in inner.iter() {
-                    wl.push(v);
-                }
-                added = inner.len();
-            }
-        }
-    }
-
-    m.replace(0, Value::new_inline(counter + added as i32));
-    reader.set_pc(PrimOpPhase::DeepSeqPush.ip() as usize);
-    Step::Continue(())
-}
-
 pub fn force_result_shallow<'gc, M: Machine<'gc>>(
     m: &mut M,
     ctx: &mut impl VmRuntimeCtx,
@@ -170,10 +110,10 @@ pub fn force_result_shallow<'gc, M: Machine<'gc>>(
     m.force_slot(0, reader, mc)?;
     let val = m.peek_forced(0);
 
-    let (count, has_children) = if let Some(attrs) = val.as_gc::<AttrSet>() {
+    let (count, has_children) = if let Some(attrs) = val.downcast::<AttrSet>() {
         let len = attrs.entries.len();
         (len, len > 0)
-    } else if let Some(list) = val.as_gc::<List<'gc>>() {
+    } else if let Some(list) = val.downcast::<List>() {
         let len = list.inner.borrow().len();
         (len, len > 0)
     } else {
@@ -185,49 +125,56 @@ pub fn force_result_shallow<'gc, M: Machine<'gc>>(
         return m.finish_ok(ctx.convert_value(val));
     }
 
-    m.push(Value::new_inline(0i32));
-    m.push(Value::new_inline(count as i32));
-    reader.set_pc(PrimOpPhase::ForceResultShallowPush.ip() as usize);
+    m.push(Value::new(0i32));
+    m.push(Value::new(count as i32));
+    reader.set_pc(Continuation::ForceResultShallowPush.ip() as usize);
     Step::Continue(())
 }
 
+#[expect(
+    clippy::cast_sign_loss,
+    reason = "idx is a non-negative loop counter (0..=len); used only with .get(), so the cast is always a valid index or safely out of range"
+)]
 pub fn force_result_shallow_push<'gc, M: Machine<'gc>>(
     m: &mut M,
     ctx: &mut impl VmRuntimeCtx,
     reader: &mut BytecodeReader<'_>,
     mc: &Mutation<'gc>,
 ) -> Step {
-    #[allow(clippy::unwrap_used)]
-    let idx = m.peek(1).as_inline::<i32>().unwrap();
-    #[allow(clippy::unwrap_used)]
-    let len = m.peek(0).as_inline::<i32>().unwrap();
+    let idx = m
+        .peek(1)
+        .downcast::<i32>()
+        .expect("stack slot must be an integer");
+    let len = m
+        .peek(0)
+        .downcast::<i32>()
+        .expect("stack slot must be an integer");
 
     if idx == len {
-        let _ = m.pop(); // len
-        let _ = m.pop(); // idx
+        m.drop_n(2);
         let val = m.pop();
         return m.finish_ok(ctx.convert_value(val));
     }
 
     let val = m.peek_forced(2);
-    let child = if let Some(attrs) = val.as_gc::<AttrSet>() {
+    let child = if let Some(attrs) = val.downcast::<AttrSet>() {
         attrs.entries.get(idx as usize).map(|&(_, v)| v)
-    } else if let Some(list) = val.as_gc::<List<'gc>>() {
+    } else if let Some(list) = val.downcast::<List>() {
         list.inner.borrow().get(idx as usize).copied()
     } else {
         None
     };
 
     if let Some(child) = child {
-        m.replace(1, Value::new_inline(idx + 1));
+        m.replace(1, Value::new(idx + 1));
         m.push(child);
         m.force_slot_to_pc(
             0,
             reader,
             mc,
-            PrimOpPhase::ForceResultShallowLoop.ip() as usize,
+            Continuation::ForceResultShallowLoop.ip() as usize,
         )?;
-        reader.set_pc(PrimOpPhase::ForceResultShallowLoop.ip() as usize);
+        reader.set_pc(Continuation::ForceResultShallowLoop.ip() as usize);
     }
     Step::Continue(())
 }
@@ -237,8 +184,8 @@ pub fn force_result_shallow_loop<'gc, M: Machine<'gc>>(
     reader: &mut BytecodeReader<'_>,
     _mc: &Mutation<'gc>,
 ) -> Step {
-    let _ = m.pop(); // forced child
-    reader.set_pc(PrimOpPhase::ForceResultShallowPush.ip() as usize);
+    m.drop_n(1);
+    reader.set_pc(Continuation::ForceResultShallowPush.ip() as usize);
     Step::Continue(())
 }
 
@@ -288,7 +235,7 @@ pub fn call_functor_1<'gc, M: Machine<'gc>>(
         reader,
         mc,
         self_val,
-        PrimOpPhase::CallFunctor2.ip() as usize,
+        Continuation::CallFunctor2.ip() as usize,
     )
 }
 
@@ -308,6 +255,10 @@ pub fn call_functor_2<'gc, M: Machine<'gc>>(
     m.call(reader, mc, orig_arg, saved.pc)
 }
 
+#[expect(
+    clippy::unreachable,
+    reason = "CallPattern is only dispatched for closures whose pattern is Some, established when the Call opcode routed here"
+)]
 pub fn call_pattern<'gc, M: Machine<'gc>>(
     m: &mut M,
     ctx: &mut impl VmRuntimeCtx,
@@ -349,7 +300,7 @@ pub fn call_pattern<'gc, M: Machine<'gc>>(
 
     let new_env = Gc::new(
         mc,
-        RefLock::new(Env::with_arg(Value::new_gc(attrset), n_locals, env)),
+        RefLock::new(Env::with_arg(Value::new(attrset), n_locals, env)),
     );
     reader.set_pc(ip as usize);
     m.set_env(new_env);

fix-vm/src/primops/conv.rs

@@ -1,9 +1,9 @@
-use fix_abstract_vm::{
+use fix_error::Error;
+use fix_lang::StringId;
+use fix_runtime::{
     BytecodeReader, Machine, MachineExt, NixString, NixType, Path, Step, StrictValue, Value,
     VmRuntimeCtx,
 };
-use fix_common::StringId;
-use fix_error::Error;
 use gc_arena::Mutation;
 
 pub fn to_string<'gc, M: Machine<'gc>>(
@@ -16,8 +16,8 @@ pub fn to_string<'gc, M: Machine<'gc>>(
     if val.is::<StringId>() || val.is::<NixString>() {
         return m.return_from_primop(val.relax(), reader);
     }
-    if let Some(p) = val.as_inline::<Path>() {
-        return m.return_from_primop(Value::new_inline(p.0), reader);
+    if let Some(p) = val.downcast::<Path>() {
+        return m.return_from_primop(Value::new(p.0), reader);
     }
     //  TODO: derivations / `__toString` / `outPath`,
     //        numbers, lists.
@@ -27,6 +27,10 @@ pub fn to_string<'gc, M: Machine<'gc>>(
     )))
 }
 
+#[expect(
+    clippy::unreachable,
+    reason = "val was forced to WHNF by force_and_retry, so its type is never Thunk here"
+)]
 pub fn type_of<'gc, M: Machine<'gc>>(
     m: &mut M,
     ctx: &mut impl VmRuntimeCtx,
@@ -47,5 +51,5 @@ pub fn type_of<'gc, M: Machine<'gc>>(
         NixType::Thunk => unreachable!("forced"),
     };
     let sid = ctx.intern_string(name);
-    m.return_from_primop(Value::new_inline(sid), reader)
+    m.return_from_primop(Value::new(sid), reader)
 }

fix-vm/src/primops/eq.rs

@@ -1,8 +1,8 @@
-use fix_abstract_vm::{
+use fix_bytecode::Continuation;
+use fix_runtime::{
     AttrSet, BytecodeReader, CallFrame, List, Machine, MachineExt, NixNum, Null, Path, Step,
     StrictValue, Value, VmRuntimeCtx, VmRuntimeCtxExt,
 };
-use fix_builtins::PrimOpPhase;
 use gc_arena::{Gc, Mutation};
 use smallvec::SmallVec;
 
@@ -17,11 +17,11 @@ pub fn start_eq<'gc, M: Machine<'gc>>(
 ) -> Step {
     match shallow_eq(ctx, lhs, rhs) {
         ShallowEq::True => {
-            m.push(Value::new_inline(!negate));
+            m.push(Value::new(!negate));
             Step::Continue(())
         }
         ShallowEq::False => {
-            m.push(Value::new_inline(negate));
+            m.push(Value::new(negate));
             Step::Continue(())
         }
         ShallowEq::RecurseList(la, lb) => {
@@ -30,10 +30,8 @@ pub fn start_eq<'gc, M: Machine<'gc>>(
             enter_eq_machine(m, reader, mc, negate, lhs_init, rhs_init)
         }
         ShallowEq::RecurseAttrs(a, b) => {
-            let lhs_init: SmallVec<[Value<'gc>; 4]> =
-                a.entries.iter().map(|&(_, v)| v).collect();
-            let rhs_init: SmallVec<[Value<'gc>; 4]> =
-                b.entries.iter().map(|&(_, v)| v).collect();
+            let lhs_init: SmallVec<[Value<'gc>; 4]> = a.entries.iter().map(|&(_, v)| v).collect();
+            let rhs_init: SmallVec<[Value<'gc>; 4]> = b.entries.iter().map(|&(_, v)| v).collect();
             enter_eq_machine(m, reader, mc, negate, lhs_init, rhs_init)
         }
     }
@@ -46,15 +44,15 @@ pub fn eq_step<'gc, M: Machine<'gc>>(
 ) -> Step {
     let rhs_q = m
         .peek(0)
-        .as_gc::<List<'gc>>()
+        .downcast::<List>()
         .expect("eq state corrupted: rhs_queue");
     let lhs_q = m
         .peek(1)
-        .as_gc::<List<'gc>>()
+        .downcast::<List>()
         .expect("eq state corrupted: lhs_queue");
     let result = m
         .peek(2)
-        .as_inline::<bool>()
+        .downcast::<bool>()
         .expect("eq state corrupted: result");
 
     if !result || lhs_q.inner.borrow().is_empty() {
@@ -73,7 +71,7 @@ pub fn eq_step<'gc, M: Machine<'gc>>(
         .expect("non-empty rhs queue");
     m.push(lhs);
     m.push(rhs);
-    reader.set_pc(PrimOpPhase::EqForce.ip() as usize);
+    reader.set_pc(Continuation::EqForce.ip() as usize);
     Step::Continue(())
 }
 
@@ -85,22 +83,21 @@ pub fn eq_force<'gc, M: Machine<'gc>>(
 ) -> Step {
     let (lhs, rhs) = m.force_and_retry::<(StrictValue, StrictValue)>(reader, mc)?;
     apply_pair(m, ctx, mc, lhs, rhs);
-    reader.set_pc(PrimOpPhase::EqStep.ip() as usize);
+    reader.set_pc(Continuation::EqStep.ip() as usize);
     Step::Continue(())
 }
 
 fn finalize<'gc, M: Machine<'gc>>(m: &mut M, reader: &mut BytecodeReader<'_>) -> Step {
-    let _ = m.pop();
-    let _ = m.pop();
+    m.drop_n(2);
     let result = m
         .pop()
-        .as_inline::<bool>()
+        .downcast::<bool>()
         .expect("eq state corrupted: result");
     let negate = m
         .pop()
-        .as_inline::<bool>()
+        .downcast::<bool>()
         .expect("eq state corrupted: negate");
-    m.return_from_primop(Value::new_inline(result ^ negate), reader)
+    m.return_from_primop(Value::new(result ^ negate), reader)
 }
 
 fn apply_pair<'gc, M: Machine<'gc>>(
@@ -113,10 +110,15 @@ fn apply_pair<'gc, M: Machine<'gc>>(
     match shallow_eq(ctx, lhs, rhs) {
         ShallowEq::True => {}
         ShallowEq::False => {
-            m.replace(2, Value::new_inline(false));
+            m.replace(2, Value::new(false));
         }
         ShallowEq::RecurseList(la, lb) => {
-            extend_queues(m, mc, la.inner.borrow().iter().copied(), lb.inner.borrow().iter().copied());
+            extend_queues(
+                m,
+                mc,
+                la.inner.borrow().iter().copied(),
+                lb.inner.borrow().iter().copied(),
+            );
         }
         ShallowEq::RecurseAttrs(a, b) => {
             extend_queues(
@@ -137,11 +139,11 @@ where
 {
     let rhs_q = m
         .peek(0)
-        .as_gc::<List<'gc>>()
+        .downcast::<List>()
         .expect("eq state corrupted: rhs_queue");
     let lhs_q = m
         .peek(1)
-        .as_gc::<List<'gc>>()
+        .downcast::<List>()
         .expect("eq state corrupted: lhs_queue");
     let mut lq = lhs_q.unlock(mc).borrow_mut();
     let mut rq = rhs_q.unlock(mc).borrow_mut();
@@ -164,13 +166,14 @@ fn enter_eq_machine<'gc, M: Machine<'gc>>(
         pc: resume_pc,
         thunk: None,
         env: m.env(),
+        depth: None,
     });
     m.inc_call_depth();
-    m.push(Value::new_inline(negate));
-    m.push(Value::new_inline(true));
-    m.push(Value::new_gc(List::new(mc, lhs_init)));
-    m.push(Value::new_gc(List::new(mc, rhs_init)));
-    reader.set_pc(PrimOpPhase::EqStep.ip() as usize);
+    m.push(Value::new(negate));
+    m.push(Value::new(true));
+    m.push(Value::new(List::new(mc, lhs_init)));
+    m.push(Value::new(List::new(mc, rhs_init)));
+    reader.set_pc(Continuation::EqStep.ip() as usize);
     Step::Continue(())
 }
 
@@ -186,7 +189,7 @@ fn shallow_eq<'gc>(
     lhs: StrictValue<'gc>,
     rhs: StrictValue<'gc>,
 ) -> ShallowEq<'gc> {
-    if let (Some(a), Some(b)) = (lhs.as_num(), rhs.as_num()) {
+    if let (Some(a), Some(b)) = (lhs.downcast_num(), rhs.downcast_num()) {
         let eq = match (a, b) {
             (NixNum::Int(a), NixNum::Int(b)) => a == b,
             (NixNum::Float(a), NixNum::Float(b)) => a == b,
@@ -195,25 +198,28 @@ fn shallow_eq<'gc>(
         };
         return bool_outcome(eq);
     }
-    if let (Some(a), Some(b)) = (lhs.as_inline::<bool>(), rhs.as_inline::<bool>()) {
+    if let (Some(a), Some(b)) = (lhs.downcast::<bool>(), rhs.downcast::<bool>()) {
         return bool_outcome(a == b);
     }
     if lhs.is::<Null>() && rhs.is::<Null>() {
         return ShallowEq::True;
     }
-    if let (Some(a), Some(b)) = (lhs.as_inline::<Path>(), rhs.as_inline::<Path>()) {
+    if let (Some(a), Some(b)) = (lhs.downcast::<Path>(), rhs.downcast::<Path>()) {
         return bool_outcome(a.0 == b.0);
     }
     if let (Some(a), Some(b)) = (ctx.get_string(lhs), ctx.get_string(rhs)) {
         return bool_outcome(a == b);
     }
-    if let (Some(a), Some(b)) = (lhs.as_gc::<List<'gc>>(), rhs.as_gc::<List<'gc>>()) {
+    if let (Some(a), Some(b)) = (lhs.downcast::<List>(), rhs.downcast::<List>()) {
         if a.inner.borrow().len() != b.inner.borrow().len() {
             return ShallowEq::False;
         }
         return ShallowEq::RecurseList(a, b);
     }
-    if let (Some(a), Some(b)) = (lhs.as_gc::<AttrSet<'gc>>(), rhs.as_gc::<AttrSet<'gc>>()) {
+    if let (Some(a), Some(b)) = (
+        lhs.downcast::<AttrSet<'gc>>(),
+        rhs.downcast::<AttrSet<'gc>>(),
+    ) {
         let ae = &a.entries;
         let be = &b.entries;
         if ae.len() != be.len() {
@@ -230,9 +236,5 @@ fn shallow_eq<'gc>(
 }
 
 fn bool_outcome<'gc>(b: bool) -> ShallowEq<'gc> {
-    if b {
-        ShallowEq::True
-    } else {
-        ShallowEq::False
-    }
+    if b { ShallowEq::True } else { ShallowEq::False }
 }

fix-vm/src/primops/io.rs

@@ -1,12 +1,12 @@
 use std::path::PathBuf;
 
-use fix_abstract_vm::{
+use fix_bytecode::Continuation;
+use fix_error::Error;
+use fix_lang::StringId;
+use fix_runtime::{
     AttrSet, Break, BytecodeReader, CallFrame, Machine, MachineExt, Path, PendingLoad,
     PendingScope, Step, StrictValue, Value, VmRuntimeCtx, VmRuntimeCtxExt, canon_path_str,
 };
-use fix_builtins::PrimOpPhase;
-use fix_common::StringId;
-use fix_error::Error;
 use gc_arena::{Gc, Mutation};
 use hashbrown::HashSet;
 
@@ -40,12 +40,13 @@ pub fn import<'gc, M: Machine<'gc>>(
     // finalizer can use it as the cache key. The slot we pop here was
     // freed by `force_and_retry`, so we simply push.
     let path_sid = ctx.intern_string(abs.to_string_lossy());
-    m.push(Value::new_inline(path_sid));
+    m.push(Value::new(path_sid));
     let env = m.env();
     m.push_call_frame(CallFrame {
-        pc: PrimOpPhase::ImportFinalize.ip() as usize,
+        pc: Continuation::PImportFinalize.ip() as usize,
         thunk: None,
         env,
+        depth: None,
     });
 
     m.set_pending_load(PendingLoad {
@@ -55,6 +56,10 @@ pub fn import<'gc, M: Machine<'gc>>(
     Step::Break(Break::LoadFile)
 }
 
+#[expect(
+    clippy::unreachable,
+    reason = "import always pushes the PImportFinalize call frame before this runs, so pop_call_frame is always Some"
+)]
 pub fn import_finalize<'gc, M: Machine<'gc>>(
     m: &mut M,
     ctx: &mut impl VmRuntimeCtx,
@@ -62,8 +67,10 @@ pub fn import_finalize<'gc, M: Machine<'gc>>(
 ) -> Step {
     // stack: [path_sid, return_value]
     let val = m.pop();
-    #[allow(clippy::unwrap_used)]
-    let path_sid = m.pop().as_inline::<StringId>().unwrap();
+    let path_sid = m
+        .pop()
+        .downcast::<StringId>()
+        .expect("stack slot must be a string");
     // The cache key is keyed by the absolute path string we interned in
     // `import`. Resolve it back to the host PathBuf.
     let path_str = ctx.resolve_string(path_sid).to_owned();
@@ -73,6 +80,7 @@ pub fn import_finalize<'gc, M: Machine<'gc>>(
         pc: ret_pc,
         thunk: _,
         env,
+        depth: None,
     }) = m.pop_call_frame()
     else {
         unreachable!()
@@ -107,13 +115,14 @@ pub fn scoped_import<'gc, M: Machine<'gc>>(
     };
 
     let keys: HashSet<StringId> = scope_attrs.entries.iter().map(|&(k, _)| k).collect();
-    let slot_id = m.scope_slots_push(Value::new_gc(scope_attrs));
+    let slot_id = m.scope_slots_push(Value::new(scope_attrs));
 
     let env = m.env();
     m.push_call_frame(CallFrame {
-        pc: PrimOpPhase::ScopedImportFinalize.ip() as usize,
+        pc: Continuation::PScopedImportFinalize.ip() as usize,
         thunk: None,
         env,
+        depth: None,
     });
 
     m.set_pending_load(PendingLoad {
@@ -146,7 +155,7 @@ pub fn path_exists<'gc, M: Machine<'gc>>(
     let path_val = m.force_and_retry::<StrictValue>(reader, mc)?;
     // pathExists requires an absolute path. A `Path` value is
     // always absolute; a string is accepted only if it starts with `/`.
-    let (path, is_path_value) = if let Some(p) = path_val.as_inline::<Path>() {
+    let (path, is_path_value) = if let Some(p) = path_val.downcast::<Path>() {
         (ctx.resolve_string(p.0).to_owned(), true)
     } else if let Some(s) = ctx.get_string(path_val) {
         (s.to_owned(), false)
@@ -171,7 +180,7 @@ pub fn path_exists<'gc, M: Machine<'gc>>(
     } else {
         std::fs::symlink_metadata(p).is_ok()
     };
-    m.return_from_primop(Value::new_inline(exists), reader)
+    m.return_from_primop(Value::new(exists), reader)
 }
 
 /// Convert the user-supplied path string into an absolute, dotted-segment

fix-vm/src/primops/list.rs

@@ -0,0 +1,116 @@
+use fix_error::Result;
+use fix_macros::handler;
+use fix_runtime::{List, Slot, StrictValue, Value};
+use gc_arena::Mutation;
+
+use crate::primops::stubs::*;
+
+#[handler(name = PFilter)]
+fn filter<'gc>(
+    mc: &Mutation<'gc>,
+    pred: Slot<Value<'gc>>,
+    list: Slot<Value<'gc>>,
+) -> Result<Value<'gc>> {
+    let list: Slot<List<'gc>> = force(list).await?;
+    if list.get().inner.borrow().is_empty() {
+        return Ok(Value::new(list.get()));
+    }
+    let idx: Slot<i32> = spill(0i32);
+    let acc: Slot<List<'gc>> = spill(List::new_gc(mc));
+    loop {
+        #[expect(
+            clippy::indexing_slicing,
+            reason = "idx is a non-negative loop counter in 0..list.len(), so it indexes the list in bounds"
+        )]
+        let keep: bool = call(&pred, list.get().inner.borrow()[idx.get() as usize]).await?;
+        if keep {
+            #[expect(
+                clippy::indexing_slicing,
+                reason = "idx is a non-negative loop counter in 0..list.len(), so it indexes the list in bounds"
+            )]
+            let elem = list.get().inner.borrow()[idx.get() as usize];
+            acc.get().unlock(mc).borrow_mut().push(elem);
+        }
+        if idx.get() as usize == list.get().inner.borrow().len() - 1 {
+            return Ok(Value::new(acc.get()));
+        }
+        idx.set(idx.get() + 1);
+    }
+}
+
+#[handler(name = PAll)]
+fn all<'gc>(
+    mc: &Mutation<'gc>,
+    pred: Slot<Value<'gc>>,
+    list: Slot<Value<'gc>>,
+) -> Result<Value<'gc>> {
+    let list: Slot<List<'gc>> = force(list).await?;
+    if list.get().inner.borrow().is_empty() {
+        return Ok(Value::new(true));
+    }
+    let idx: Slot<i32> = spill(0i32);
+    loop {
+        #[expect(
+            clippy::indexing_slicing,
+            reason = "idx is a non-negative loop counter in 0..list.len(), so it indexes the list in bounds"
+        )]
+        let keep: bool = call(&pred, list.get().inner.borrow()[idx.get() as usize]).await?;
+        if !keep || idx.get() as usize + 1 == list.get().inner.borrow().len() {
+            return Ok(Value::new(keep));
+        }
+        idx.set(idx.get() + 1);
+    }
+}
+
+#[handler(name = PAny)]
+fn any<'gc>(
+    mc: &Mutation<'gc>,
+    pred: Slot<Value<'gc>>,
+    list: Slot<Value<'gc>>,
+) -> Result<Value<'gc>> {
+    let list: Slot<List<'gc>> = force(list).await?;
+    if list.get().inner.borrow().is_empty() {
+        return Ok(Value::new(false));
+    }
+    let idx: Slot<i32> = spill(0i32);
+    loop {
+        #[expect(
+            clippy::indexing_slicing,
+            reason = "idx is a non-negative loop counter in 0..list.len(), so it indexes the list in bounds"
+        )]
+        let keep: bool = call(&pred, list.get().inner.borrow()[idx.get() as usize]).await?;
+        if keep || idx.get() as usize + 1 == list.get().inner.borrow().len() {
+            return Ok(Value::new(keep));
+        }
+        idx.set(idx.get() + 1);
+    }
+}
+
+#[handler(name = PFoldlStrict)]
+fn foldl_strict<'gc>(
+    mc: &Mutation<'gc>,
+    op: Slot<Value<'gc>>,
+    nul: Slot<Value<'gc>>,
+    list: Slot<Value<'gc>>,
+) -> Result<Value<'gc>> {
+    let list: Slot<List<'gc>> = force(list).await?;
+    if list.get().inner.borrow().is_empty() {
+        return Ok(nul.get());
+    }
+    let idx: Slot<i32> = spill(0i32);
+    let acc = spill(nul.get());
+    loop {
+        let f = call(&op, acc.get()).await?;
+        #[expect(
+            clippy::indexing_slicing,
+            reason = "idx is a non-negative loop counter in 0..list.len(), so it indexes the list in bounds"
+        )]
+        let new_acc: StrictValue<'gc> =
+            call(&f, list.get().inner.borrow()[idx.get() as usize]).await?;
+        acc.set(new_acc.relax());
+        if idx.get() as usize + 1 == list.get().inner.borrow().len() {
+            return Ok(acc.get());
+        }
+        idx.set(idx.get() + 1);
+    }
+}

fix-vm/src/primops/mod.rs

@@ -0,0 +1,88 @@
+mod context;
+mod control;
+mod conv;
+mod eq;
+mod io;
+mod list;
+mod path;
+mod stubs;
+
+pub use context::*;
+pub use control::*;
+pub use conv::*;
+pub use eq::*;
+use fix_bytecode::Continuation;
+use fix_error::Error;
+use fix_runtime::{BytecodeReader, Machine, Step, VmRuntimeCtx};
+use gc_arena::Mutation;
+pub use io::*;
+pub use list::*;
+pub use path::*;
+
+pub fn dispatch_cont<'gc, M: Machine<'gc>>(
+    m: &mut M,
+    ctx: &mut impl VmRuntimeCtx,
+    reader: &mut BytecodeReader<'_>,
+    mc: &Mutation<'gc>,
+) -> Step {
+    use Continuation::*;
+    let cont = reader.read_u8();
+    let Ok(cont) = Continuation::try_from(cont) else {
+        return m.finish_err(Error::eval_error("invalid primop phase"));
+    };
+    match cont {
+        PAbort => abort(m, ctx, reader, mc),
+
+        PAll0 | PAll1 | PAll2 | PAll3 => all(m, reader, mc, cont),
+        PAny0 | PAny1 | PAny2 | PAny3 => any(m, reader, mc, cont),
+        PDeepSeq0 | PDeepSeq1 | PDeepSeq2 | PDeepSeq3 | PDeepSeq4 | PDeepSeq5 => {
+            deep_seq(m, reader, mc, cont)
+        }
+        PSeq0 | PSeq1 => seq(m, reader, mc, cont),
+
+        PFilter0 | PFilter1 | PFilter2 | PFilter3 | PFilter4 => filter(m, reader, mc, cont),
+
+        PFoldlStrict0 | PFoldlStrict1 | PFoldlStrict2 | PFoldlStrict3 | PFoldlStrict4 | PFoldlStrict5 => {
+            foldl_strict(m, reader, mc, cont)
+        }
+
+        ForceResultShallow => force_result_shallow(m, ctx, reader, mc),
+        ForceResultShallowPush => force_result_shallow_push(m, ctx, reader, mc),
+        ForceResultShallowLoop => force_result_shallow_loop(m, reader, mc),
+        ForceResultDeepFinish => force_result_deep_finish(m, ctx, reader, mc),
+
+        EqStep => eq_step(m, reader, mc),
+        EqForce => eq_force(m, ctx, reader, mc),
+
+        CallPattern => call_pattern(m, ctx, reader, mc),
+        CallFunctor1 => call_functor_1(m, reader, mc),
+        CallFunctor2 => call_functor_2(m, reader, mc),
+
+        PImport => import(m, ctx, reader, mc),
+        PImportFinalize => import_finalize(m, ctx, reader),
+        PScopedImport => scoped_import(m, ctx, reader, mc),
+        PScopedImportFinalize => scoped_import_finalize(m, ctx, reader, mc),
+
+        PPathExists => path_exists(m, ctx, reader, mc),
+        PToPath => to_path(m, ctx, reader, mc),
+        PIsPath => is_path(m, reader, mc),
+        PToString => to_string(m, ctx, reader, mc),
+        PTypeOf => type_of(m, ctx, reader, mc),
+
+        PHasContext => has_context(m, ctx, reader, mc),
+        PGetContext => get_context(m, ctx, reader, mc),
+        PAppendContext => append_context(m, ctx, reader, mc),
+        PAppendContextLoop => append_context_loop(m, ctx, reader, mc),
+        PAppendContextEntryForced => append_context_entry_forced(m, ctx, reader, mc),
+        PAppendContextOutputsForced => append_context_outputs_forced(m, ctx, reader, mc),
+        PAppendContextOutputElementLoop => append_context_output_element_loop(m, ctx, reader, mc),
+        PAppendContextOutputElementForced => {
+            append_context_output_element_forced(m, ctx, reader, mc)
+        }
+
+        PUnsafeDiscardStringContext => unsafe_discard_string_context(m, ctx, reader, mc),
+        PUnsafeDiscardOutputDependency => unsafe_discard_output_dependency(m, ctx, reader, mc),
+
+        phase => todo!("primop phase {phase:?}"),
+    }
+}

fix-vm/src/primops/path.rs

@@ -1,8 +1,8 @@
-use fix_abstract_vm::{
+use fix_error::Error;
+use fix_runtime::{
     BytecodeReader, Machine, MachineExt, Path, Step, StrictValue, Value, VmRuntimeCtx,
     VmRuntimeCtxExt, canon_path_str,
 };
-use fix_error::Error;
 use gc_arena::Mutation;
 
 pub fn to_path<'gc, M: Machine<'gc>>(
@@ -13,8 +13,8 @@ pub fn to_path<'gc, M: Machine<'gc>>(
 ) -> Step {
     // coerce to path THEN TO STRING
     let val = m.force_and_retry::<StrictValue>(reader, mc)?;
-    if let Some(Path(s)) = val.as_inline::<Path>() {
-        return m.return_from_primop(Value::new_inline(s), reader);
+    if let Some(Path(s)) = val.downcast::<Path>() {
+        return m.return_from_primop(Value::new(s), reader);
     }
     let Some(s) = ctx.get_string(val) else {
         return m.finish_err(Error::eval_error(format!(
@@ -29,7 +29,7 @@ pub fn to_path<'gc, M: Machine<'gc>>(
     }
     let canon = canon_path_str(s);
     let sid = ctx.intern_string(canon);
-    m.return_from_primop(Value::new_inline(sid), reader)
+    m.return_from_primop(Value::new(sid), reader)
 }
 
 pub fn is_path<'gc, M: Machine<'gc>>(
@@ -39,5 +39,5 @@ pub fn is_path<'gc, M: Machine<'gc>>(
 ) -> Step {
     let val = m.force_and_retry::<StrictValue>(reader, mc)?;
     let is_path = val.is::<Path>();
-    m.return_from_primop(Value::new_inline(is_path), reader)
+    m.return_from_primop(Value::new(is_path), reader)
 }

fix-vm/src/primops/stubs.rs

@@ -0,0 +1,9 @@
+//! Fallback definitions for the `#[primop]` surface syntax.
+//!
+//! `force`, `call`, and `spill` are recognized and rewritten by the
+//! `#[primop]` proc macro, so compiled code never calls them. They exist only
+//! so the un-expanded source name-resolves in tooling that does not run the
+//! macro (e.g. rust-analyzer while the macro crate is being rebuilt). Calling
+//! one for real is impossible: they never return.
+
+pub use crate::__macro_support::{call, force, spill};

fix/Cargo.toml

@@ -3,6 +3,18 @@ name = "fix"
 version = "0.1.0"
 edition = "2024"
 
+[[bench]]
+harness = false
+name = "basic_ops"
+
+[[bench]]
+harness = false
+name = "builtins"
+
+[[bench]]
+harness = false
+name = "thunk_scope"
+
 [dependencies]
 mimalloc = "0.1"
 
@@ -17,43 +29,28 @@ clap = { version = "4", features = ["derive"] }
 tracing = "0.1"
 tracing-subscriber = { version = "0.3", features = ["env-filter"] }
 
+miette = { version = "7.4", features = ["fancy"] }
 # Error Reporting
 thiserror = "2"
-miette = { version = "7.4", features = ["fancy"] }
 
 # Data Structure
 hashbrown = { workspace = true }
 string-interner = { workspace = true }
 
-# Memory Management
-bumpalo = { workspace = true }
-
-rnix = { workspace = true }
-
 ere = { workspace = true }
-ghost-cell = { workspace = true }
 
-fix-abstract-vm = { path = "../fix-abstract-vm" }
-fix-builtins = { path = "../fix-builtins" }
-fix-common = { path = "../fix-common" }
-fix-codegen = { path = "../fix-codegen" }
+fix-bytecode = { path = "../fix-bytecode" }
+fix-compiler = { path = "../fix-compiler" }
 fix-error = { path = "../fix-error" }
-fix-ir = { path = "../fix-ir" }
+fix-lang = { path = "../fix-lang" }
+fix-runtime = { path = "../fix-runtime" }
 fix-vm = { path = "../fix-vm" }
 
 [dev-dependencies]
 criterion = { version = "0.8", features = ["html_reports"] }
+serial_test = "4.0"
 tempfile = "3.24"
 test-log = { version = "0.2", features = ["trace"] }
 
-[[bench]]
-name = "basic_ops"
-harness = false
-
-[[bench]]
-name = "builtins"
-harness = false
-
-[[bench]]
-name = "thunk_scope"
-harness = false
+[lints]
+workspace = true

fix/benches/utils.rs

@@ -1,8 +1,9 @@
-#![allow(dead_code)]
+#![allow(clippy::allow_attributes_without_reason)]
+#![allow(dead_code, clippy::unwrap_used, clippy::unwrap_in_result)]
 
 use fix::Evaluator;
-use fix_common::Value;
 use fix_error::{Result, Source};
+use fix_lang::Value;
 
 pub fn eval(expr: &str) -> Value {
     Evaluator::new()

fix/src/lib.rs

@@ -1,24 +1,13 @@
-#![warn(clippy::unwrap_used)]
-#![allow(dead_code)]
-
-use bumpalo::Bump;
-use fix_abstract_vm::{ForceMode, StaticValue, VmCode, VmContext, VmRuntimeCtx};
-use fix_builtins::PrimOpPhase;
-use fix_codegen::disassembler::{Disassembler, DisassemblerContext};
-use fix_codegen::{BytecodeContext, InstructionPtr, Op};
-use fix_common::{StringId, Symbol};
-use fix_error::{Error, Result, Source};
-use fix_ir::downgrade::{Downgrade as _, DowngradeContext};
-use fix_ir::{
-    GhostMaybeThunkRef, GhostRoIrRef, GhostRoMaybeThunkRef, GhostRoRef, Ir, MaybeThunk, RawIrRef,
-    ThunkId,
-};
+use fix_bytecode::InstructionPtr;
+use fix_bytecode::disassembler::{Disassembler, DisassemblerContext};
+use fix_compiler::{CodeState, ExtraScope};
+use fix_error::{Result, Source};
+use fix_lang::StringId;
+use fix_runtime::{ForceMode, StaticValue, VmCode, VmContext, VmRuntimeCtx};
 use fix_vm::Vm;
-use ghost_cell::{GhostCell, GhostToken};
 use hashbrown::{HashMap, HashSet};
 use string_interner::{DefaultStringInterner, Symbol as _};
 
-mod derivation;
 pub mod logging;
 
 #[global_allocator]
@@ -29,15 +18,6 @@ pub struct RuntimeState {
     pub constants: Constants,
 }
 
-pub struct CodeState {
-    pub bytecode: Vec<u8>,
-    pub sources: Vec<Source>,
-    pub spans: Vec<(usize, rnix::TextRange)>,
-    pub thunk_count: usize,
-    pub global_env: HashMap<StringId, MaybeThunk>,
-    pub current_scope_slot: Option<u32>,
-}
-
 pub struct Evaluator {
     pub runtime: RuntimeState,
     pub code: CodeState,
@@ -52,37 +32,25 @@ impl Default for Evaluator {
 impl Evaluator {
     pub fn new() -> Self {
         let mut strings = DefaultStringInterner::new();
-        let global_env = fix_ir::new_global_env(&mut strings);
-        let mut bytecode = Vec::with_capacity(PrimOpPhase::Illegal as usize * 2);
-        for phase in 0..=PrimOpPhase::Illegal as u8 {
-            bytecode.push(Op::DispatchPrimOp as u8);
-            bytecode.push(phase);
-        }
+        let code = CodeState::new(&mut strings);
         Self {
             runtime: RuntimeState {
                 strings,
                 constants: Constants::default(),
             },
-            code: CodeState {
-                sources: Vec::new(),
-                spans: Vec::new(),
-                thunk_count: 0,
-                bytecode,
-                global_env,
-                current_scope_slot: None,
-            },
+            code,
         }
     }
 
-    pub fn eval(&mut self, source: Source) -> Result<fix_common::Value> {
+    pub fn eval(&mut self, source: Source) -> Result<fix_lang::Value> {
         self.do_eval(source, None, ForceMode::AsIs)
     }
 
-    pub fn eval_shallow(&mut self, source: Source) -> Result<fix_common::Value> {
+    pub fn eval_shallow(&mut self, source: Source) -> Result<fix_lang::Value> {
         self.do_eval(source, None, ForceMode::Shallow)
     }
 
-    pub fn eval_deep(&mut self, source: Source) -> Result<fix_common::Value> {
+    pub fn eval_deep(&mut self, source: Source) -> Result<fix_lang::Value> {
         self.do_eval(source, None, ForceMode::Deep)
     }
 
@@ -90,7 +58,7 @@ impl Evaluator {
         &mut self,
         source: Source,
         scope: &HashSet<StringId>,
-    ) -> Result<fix_common::Value> {
+    ) -> Result<fix_lang::Value> {
         self.do_eval(source, Some(ExtraScope::Repl(scope)), ForceMode::Shallow)
     }
 
@@ -99,14 +67,10 @@ impl Evaluator {
         source: Source,
         extra_scope: Option<ExtraScope<'ctx>>,
         force_mode: ForceMode,
-    ) -> Result<fix_common::Value> {
-        let ip = {
-            let mut compiler = CompilerCtx {
-                code: &mut self.code,
-                runtime: &mut self.runtime,
-            };
-            compiler.compile_bytecode(source, extra_scope)?
-        };
+    ) -> Result<fix_lang::Value> {
+        let ip = self
+            .code
+            .compile_bytecode(source, extra_scope, &mut self.runtime)?;
         Vm::run(self, ip, force_mode)
     }
 
@@ -115,16 +79,12 @@ impl Evaluator {
         _ident: &str,
         _expr: &str,
         _scope: &mut HashSet<StringId>,
-    ) -> Result<fix_common::Value> {
+    ) -> Result<fix_lang::Value> {
         todo!("add_binding")
     }
 
     pub fn compile_bytecode(&mut self, source: Source) -> Result<InstructionPtr> {
-        let mut compiler = CompilerCtx {
-            code: &mut self.code,
-            runtime: &mut self.runtime,
-        };
-        compiler.compile_bytecode(source, None)
+        self.code.compile_bytecode(source, None, &mut self.runtime)
     }
 
     pub fn disassemble_colored(&self, ip: InstructionPtr) -> String {
@@ -137,163 +97,24 @@ impl VmRuntimeCtx for RuntimeState {
         StringId(self.strings.get_or_intern(s))
     }
     fn resolve_string(&self, id: StringId) -> &str {
-        #[allow(clippy::unwrap_used)]
-        self.strings.resolve(id.0).unwrap()
+        self.strings
+            .resolve(id.0)
+            .expect("interned string id must resolve")
     }
     fn get_const(&self, id: u32) -> StaticValue {
-        #[allow(clippy::unwrap_used)]
-        self.constants.get(id).unwrap()
+        self.constants.get(id).expect("const id must be valid")
     }
     fn add_const(&mut self, val: StaticValue) -> u32 {
         self.constants.insert(val)
     }
 }
 
-impl VmCode for CodeState {
-    fn bytecode(&self) -> &[u8] {
-        &self.bytecode
-    }
-    fn compile_with_scope(
-        &mut self,
-        source: Source,
-        extra_scope: Option<fix_abstract_vm::ExtraScope>,
-        runtime: &mut impl VmRuntimeCtx,
-    ) -> Result<InstructionPtr> {
-        let mut compiler = CompilerCtx {
-            code: self,
-            runtime,
-        };
-        let extra = extra_scope.map(|s| match s {
-            fix_abstract_vm::ExtraScope::ScopedImport { keys, slot_id } => {
-                ExtraScope::ScopedImport { keys, slot_id }
-            }
-        });
-        compiler.compile_bytecode(source, extra)
-    }
-}
-
 impl VmContext for Evaluator {
     fn split(&mut self) -> (&mut impl VmCode, &mut impl VmRuntimeCtx) {
         (&mut self.code, &mut self.runtime)
     }
 }
 
-struct CompilerCtx<'a, R: VmRuntimeCtx> {
-    code: &'a mut CodeState,
-    runtime: &'a mut R,
-}
-
-impl<'a, R: VmRuntimeCtx> CompilerCtx<'a, R> {
-    fn compile_bytecode(
-        &mut self,
-        source: Source,
-        extra_scope: Option<ExtraScope>,
-    ) -> Result<InstructionPtr> {
-        let prev_scope_slot = self.code.current_scope_slot;
-        self.code.current_scope_slot = match &extra_scope {
-            Some(ExtraScope::ScopedImport { slot_id, .. }) => Some(*slot_id),
-            _ => None,
-        };
-        let result = (|| -> Result<InstructionPtr> {
-            let root = self.downgrade(source, extra_scope)?;
-            let ip = fix_codegen::compile_bytecode(root.as_ref(), self);
-            Ok(ip)
-        })();
-        self.code.current_scope_slot = prev_scope_slot;
-        result
-    }
-
-    fn downgrade(&mut self, source: Source, extra_scope: Option<ExtraScope>) -> Result<OwnedIr> {
-        tracing::debug!("Parsing Nix expression");
-
-        self.code.sources.push(source.clone());
-
-        let root = rnix::Root::parse(&source.src);
-        handle_parse_error(root.errors(), source.clone()).map_or(Ok(()), Err)?;
-
-        tracing::debug!("Downgrading Nix expression");
-        let expr = root
-            .tree()
-            .expr()
-            .ok_or_else(|| Error::parse_error("unexpected EOF".into()))?;
-        let bump = Bump::new();
-        GhostToken::new(|token| {
-            let downgrade_ctx = DowngradeCtx::new(
-                &bump,
-                token,
-                self.runtime,
-                &self.code.global_env,
-                extra_scope.map(Into::into),
-                &mut self.code.thunk_count,
-                source,
-            );
-            let ir = downgrade_ctx.downgrade_toplevel(expr)?;
-            let ir = unsafe { std::mem::transmute::<RawIrRef<'_>, RawIrRef<'static>>(ir) };
-            Ok(OwnedIr { _bump: bump, ir })
-        })
-    }
-}
-
-impl<'a, R: VmRuntimeCtx> BytecodeContext for CompilerCtx<'a, R> {
-    fn intern_string(&mut self, s: &str) -> StringId {
-        self.runtime.intern_string(s)
-    }
-
-    fn register_span(&mut self, range: rnix::TextRange) -> u32 {
-        let id = self.code.spans.len();
-        let source_id = self
-            .code
-            .sources
-            .len()
-            .checked_sub(1)
-            .expect("current_source not set");
-        self.code.spans.push((source_id, range));
-        id as u32
-    }
-
-    fn get_code(&self) -> &[u8] {
-        &self.code.bytecode
-    }
-
-    fn get_code_mut(&mut self) -> &mut Vec<u8> {
-        &mut self.code.bytecode
-    }
-
-    fn add_constant(&mut self, val: fix_codegen::Const) -> u32 {
-        use fix_codegen::Const::*;
-        let val = match val {
-            Smi(x) => StaticValue::new_inline(x),
-            Float(x) => StaticValue::new_float(x),
-            Bool(x) => StaticValue::new_inline(x),
-            String(x) => StaticValue::new_inline(x),
-            Path(_) => todo!("path value type"),
-            PrimOp {
-                id,
-                arity,
-                dispatch_ip,
-            } => StaticValue::new_primop(id, arity, dispatch_ip),
-            Null => StaticValue::default(),
-        };
-        self.runtime.add_const(val)
-    }
-
-    fn current_source_dir(&mut self) -> StringId {
-        let dir = self
-            .code
-            .sources
-            .last()
-            .expect("current_source not set")
-            .get_dir()
-            .to_string_lossy()
-            .into_owned();
-        self.runtime.intern_string(dir)
-    }
-
-    fn current_scope_slot(&self) -> Option<u32> {
-        self.code.current_scope_slot
-    }
-}
-
 #[derive(Default)]
 pub struct Constants {
     data: Vec<StaticValue>,
@@ -315,410 +136,14 @@ impl Constants {
     }
 }
 
-fn parse_error_span(error: &rnix::ParseError) -> Option<rnix::TextRange> {
-    use rnix::ParseError::*;
-    match error {
-        Unexpected(range)
-        | UnexpectedExtra(range)
-        | UnexpectedWanted(_, range, _)
-        | UnexpectedDoubleBind(range)
-        | DuplicatedArgs(range, _) => Some(*range),
-        _ => None,
-    }
-}
-
-fn handle_parse_error<'a>(
-    errors: impl IntoIterator<Item = &'a rnix::ParseError>,
-    source: Source,
-) -> Option<Box<Error>> {
-    for err in errors {
-        if let Some(span) = parse_error_span(err) {
-            return Some(
-                Error::parse_error(err.to_string())
-                    .with_source(source)
-                    .with_span(span),
-            );
-        }
-    }
-    None
-}
-
-struct DowngradeCtx<'ctx, 'id, 'ir, R: VmRuntimeCtx> {
-    bump: &'ir Bump,
-    token: GhostToken<'id>,
-    runtime: &'ctx mut R,
-    source: Source,
-    scopes: Vec<Scope<'ctx, 'id, 'ir>>,
-    with_stack: Vec<GhostRoMaybeThunkRef<'id, 'ir>>,
-    arg_count: u32,
-    thunk_count: &'ctx mut usize,
-    thunk_scopes: Vec<ThunkScope<'id, 'ir>>,
-}
-
-impl<'ctx, 'id, 'ir, R: VmRuntimeCtx> DowngradeCtx<'ctx, 'id, 'ir, R> {
-    fn new(
-        bump: &'ir Bump,
-        token: GhostToken<'id>,
-        runtime: &'ctx mut R,
-        global: &'ctx HashMap<StringId, MaybeThunk>,
-        extra_scope: Option<Scope<'ctx, 'id, 'ir>>,
-        thunk_count: &'ctx mut usize,
-        source: Source,
-    ) -> Self {
-        Self {
-            bump,
-            token,
-            runtime,
-            source,
-            scopes: std::iter::once(Scope::Global(global))
-                .chain(extra_scope)
-                .collect(),
-            thunk_count,
-            arg_count: 0,
-            with_stack: Vec::new(),
-            thunk_scopes: vec![ThunkScope::new_in(bump)],
-        }
-    }
-}
-
-impl<'ctx: 'ir, 'id, 'ir, R: VmRuntimeCtx> DowngradeContext<'id, 'ir>
-    for DowngradeCtx<'ctx, 'id, 'ir, R>
-{
-    fn new_expr(&self, expr: Ir<'ir, GhostRoRef<'id, 'ir>>) -> GhostRoIrRef<'id, 'ir> {
-        self.bump.alloc(GhostCell::new(expr).into())
-    }
-
-    fn maybe_thunk(&mut self, ir: GhostRoIrRef<'id, 'ir>) -> GhostRoMaybeThunkRef<'id, 'ir> {
-        use MaybeThunk::*;
-        let expr = (|| {
-            let expr = match *ir.borrow(&self.token) {
-                Ir::Builtin(x) => Builtin(x),
-                Ir::Int(x) => Int(x),
-                Ir::Float(x) => Float(x),
-                Ir::Bool(x) => Bool(x),
-                Ir::Str(x) => Str(x),
-                Ir::Arg { layer } => Arg { layer },
-                Ir::Builtins => Builtins,
-                Ir::Null => Null,
-                Ir::MaybeThunk(thunk) => return Some(thunk),
-                _ => return None,
-            };
-            Some(self.bump.alloc(GhostCell::new(expr).into()))
-        })();
-        if let Some(thunk) = expr {
-            return thunk;
-        }
-        let id = ThunkId(*self.thunk_count);
-        *self.thunk_count = self.thunk_count.checked_add(1).expect("thunk id overflow");
-        self.thunk_scopes
-            .last_mut()
-            .expect("no active cache scope")
-            .add_binding(id, ir);
-        self.bump.alloc(GhostCell::new(Thunk(id)).into())
-    }
-
-    fn intern_string(&mut self, sym: impl AsRef<str>) -> StringId {
-        self.runtime.intern_string(sym)
-    }
-
-    fn resolve_sym(&self, id: StringId) -> Symbol<'_> {
-        self.runtime.resolve_string(id).into()
-    }
-
-    fn lookup(
-        &mut self,
-        sym: StringId,
-        span: rnix::TextRange,
-    ) -> Result<GhostRoMaybeThunkRef<'id, 'ir>> {
-        for scope in self.scopes.iter().rev() {
-            match scope {
-                &Scope::Global(global_scope) => {
-                    if let Some(expr) = global_scope.get(&sym) {
-                        return Ok(expr.into());
-                    }
-                }
-                &Scope::Repl(repl_bindings) => {
-                    if repl_bindings.contains(&sym) {
-                        return Ok(self
-                            .bump
-                            .alloc(GhostCell::new(MaybeThunk::ReplBinding(sym)).into()));
-                    }
-                }
-                Scope::ScopedImport { keys, .. } => {
-                    if keys.contains(&sym) {
-                        return Ok(self
-                            .bump
-                            .alloc(GhostCell::new(MaybeThunk::ScopedImportBinding(sym)).into()));
-                    }
-                }
-                Scope::Let(let_scope) => {
-                    if let Some(&expr) = let_scope.get(&sym) {
-                        return Ok(expr.into());
-                    }
-                }
-                &Scope::Param {
-                    sym: param_sym,
-                    abs_layer,
-                } => {
-                    if param_sym == sym {
-                        let layers: u8 =
-                            self.thunk_scopes.len().try_into().expect("scope too deep!");
-                        let layer = layers - abs_layer;
-                        return Ok(self
-                            .bump
-                            .alloc(GhostCell::new(MaybeThunk::Arg { layer }).into()));
-                    }
-                }
-            }
-        }
-
-        if !self.with_stack.is_empty() {
-            let id = ThunkId(*self.thunk_count);
-            *self.thunk_count = self.thunk_count.checked_add(1).expect("thunk id overflow");
-            let mut namespaces =
-                bumpalo::collections::Vec::with_capacity_in(self.with_stack.len(), self.bump);
-            namespaces.extend(self.with_stack.iter().rev().copied());
-            let body = self
-                .bump
-                .alloc(GhostCell::new(Ir::WithLookup { sym, namespaces }).into());
-            self.thunk_scopes
-                .last_mut()
-                .expect("no active thunk scope")
-                .add_binding(id, body);
-            Ok(self
-                .bump
-                .alloc(GhostCell::new(MaybeThunk::Thunk(id)).into()))
-        } else {
-            Err(Error::downgrade_error(
-                format!("'{}' not found", self.resolve_sym(sym)),
-                self.get_current_source(),
-                span,
-            ))
-        }
-    }
-
-    fn get_current_source(&self) -> Source {
-        self.source.clone()
-    }
-
-    fn with_let_scope<F, Ret>(&mut self, keys: &[StringId], f: F) -> Result<Ret>
-    where
-        F: FnOnce(
-            &mut Self,
-        ) -> Result<(
-            bumpalo::collections::Vec<'ir, GhostRoMaybeThunkRef<'id, 'ir>>,
-            Ret,
-        )>,
-    {
-        let base = *self.thunk_count;
-        *self.thunk_count = self
-            .thunk_count
-            .checked_add(keys.len())
-            .expect("thunk id overflow");
-        let handles = (base..base + keys.len())
-            .map(|id| {
-                &*self
-                    .bump
-                    .alloc(GhostCell::new(MaybeThunk::Thunk(ThunkId(id))))
-            })
-            .collect::<Vec<_>>();
-        let scope = keys.iter().copied().zip(handles.iter().copied()).collect();
-        self.scopes.push(Scope::Let(scope));
-        let (vals, ret) = { f(self)? };
-        self.scopes.pop();
-        assert_eq!(keys.len(), vals.len());
-        let scope = self.thunk_scopes.last_mut().expect("no active thunk scope");
-        for (i, (val, handle)) in vals.into_iter().zip(handles).enumerate() {
-            let thunk = *val.borrow(&self.token);
-            *handle.borrow_mut(&mut self.token) = thunk;
-            let id = ThunkId(base + i);
-            let ir_ref = self
-                .bump
-                .alloc(GhostCell::new(Ir::MaybeThunk(handle.into())).into());
-            scope.add_binding(id, ir_ref);
-        }
-        Ok(ret)
-    }
-
-    fn with_param_scope<F, Ret>(&mut self, sym: StringId, f: F) -> Ret
-    where
-        F: FnOnce(&mut Self) -> Ret,
-    {
-        self.scopes.push(Scope::Param {
-            sym,
-            abs_layer: self.thunk_scopes.len().try_into().expect("scope too deep!"),
-        });
-        let mut guard = ScopeGuard { ctx: self };
-        f(guard.as_ctx())
-    }
-
-    fn with_with_scope<F, Ret>(&mut self, namespace: GhostRoMaybeThunkRef<'id, 'ir>, f: F) -> Ret
-    where
-        F: FnOnce(&mut Self) -> Ret,
-    {
-        self.with_stack.push(namespace);
-        let ret = f(self);
-        self.with_stack.pop();
-        ret
-    }
-
-    fn with_thunk_scope<F, Ret>(
-        &mut self,
-        f: F,
-    ) -> (
-        Ret,
-        bumpalo::collections::Vec<'ir, (ThunkId, GhostRoIrRef<'id, 'ir>)>,
-    )
-    where
-        F: FnOnce(&mut Self) -> Ret,
-    {
-        if self.thunk_scopes.len() == u8::MAX as usize {
-            panic!("scope too deep!");
-        }
-        self.thunk_scopes.push(ThunkScope::new_in(self.bump));
-        let ret = f(self);
-        (
-            ret,
-            self.thunk_scopes
-                .pop()
-                .expect("no thunk scope left???")
-                .bindings,
-        )
-    }
-
-    fn bump(&self) -> &'ir bumpalo::Bump {
-        self.bump
-    }
-}
-
-impl<'id, 'ir, 'ctx: 'ir, R: VmRuntimeCtx> DowngradeCtx<'ctx, 'id, 'ir, R> {
-    fn downgrade_toplevel(mut self, root: rnix::ast::Expr) -> Result<RawIrRef<'ir>> {
-        let body = root.downgrade(&mut self)?;
-        let thunks = self
-            .thunk_scopes
-            .pop()
-            .expect("no thunk scope left???")
-            .bindings;
-        Ok(Ir::freeze(
-            self.new_expr(Ir::TopLevel { body, thunks }),
-            self.token,
-        ))
-    }
-}
-
-struct ThunkScope<'id, 'ir> {
-    bindings: bumpalo::collections::Vec<'ir, (ThunkId, GhostRoIrRef<'id, 'ir>)>,
-}
-
-impl<'id, 'ir> ThunkScope<'id, 'ir> {
-    fn new_in(bump: &'ir Bump) -> Self {
-        Self {
-            bindings: bumpalo::collections::Vec::new_in(bump),
-        }
-    }
-
-    fn add_binding(&mut self, id: ThunkId, ir: GhostRoIrRef<'id, 'ir>) {
-        self.bindings.push((id, ir));
-    }
-
-    fn extend_bindings(
-        &mut self,
-        iter: impl IntoIterator<Item = (ThunkId, GhostRoIrRef<'id, 'ir>)>,
-    ) {
-        self.bindings.extend(iter);
-    }
-}
-
-enum Scope<'ctx, 'id, 'ir> {
-    Global(&'ctx HashMap<StringId, MaybeThunk>),
-    Repl(&'ctx HashSet<StringId>),
-    ScopedImport {
-        keys: HashSet<StringId>,
-        slot_id: u32,
-    },
-    Let(HashMap<StringId, GhostMaybeThunkRef<'id, 'ir>>),
-    Param {
-        sym: StringId,
-        abs_layer: u8,
-    },
-}
-
-pub enum ExtraScope<'ctx> {
-    Repl(&'ctx HashSet<StringId>),
-    ScopedImport {
-        keys: HashSet<StringId>,
-        slot_id: u32,
-    },
-}
-
-impl<'ctx> From<ExtraScope<'ctx>> for Scope<'ctx, '_, '_> {
-    fn from(value: ExtraScope<'ctx>) -> Self {
-        use ExtraScope::*;
-        match value {
-            ScopedImport { keys, slot_id } => Scope::ScopedImport { keys, slot_id },
-            Repl(scope) => Scope::Repl(scope),
-        }
-    }
-}
-
-struct ScopeGuard<'a, 'ctx, 'id, 'ir, R: VmRuntimeCtx> {
-    ctx: &'a mut DowngradeCtx<'ctx, 'id, 'ir, R>,
-}
-
-impl<'a, 'ctx, 'id, 'ir, R: VmRuntimeCtx> Drop for ScopeGuard<'a, 'ctx, 'id, 'ir, R> {
-    fn drop(&mut self) {
-        self.ctx.scopes.pop();
-    }
-}
-
-impl<'a, 'ctx, 'id, 'ir, R: VmRuntimeCtx> ScopeGuard<'a, 'ctx, 'id, 'ir, R> {
-    fn as_ctx(&mut self) -> &mut DowngradeCtx<'ctx, 'id, 'ir, R> {
-        self.ctx
-    }
-}
-
-struct OwnedIr {
-    _bump: Bump,
-    ir: RawIrRef<'static>,
-}
-
-impl OwnedIr {
-    /// # Safety
-    /// `ir` must be an allocation backed by `bump`. The reference's
-    /// lifetime is extended to `'static` as a placeholder; the stored IR
-    /// must only be re-borrowed via [`OwnedIr::as_ref`], which narrows
-    /// the lifetime back to that of the `&self` borrow. Moving `bump`
-    /// into the struct keeps the underlying allocation live for the
-    /// lifetime of the `OwnedIr`.
-    unsafe fn new(ir: RawIrRef<'_>, bump: Bump) -> Self {
-        Self {
-            _bump: bump,
-            // SAFETY: see function docs - caller guarantees `ir` is in `bump`,
-            // and the `'static` lifetime is a placeholder narrowed by `as_ref`.
-            ir: unsafe { std::mem::transmute::<RawIrRef<'_>, RawIrRef<'static>>(ir) },
-        }
-    }
-
-    fn as_ref<'ir>(&'ir self) -> RawIrRef<'ir> {
-        // SAFETY: narrows the placeholder `'static` lifetime stored in
-        // `self.ir` down to `'ir = &'ir self`. Lifetime shortening is
-        // logically sound for covariant positions; the transmute is only
-        // needed because `RawRef<'ir>` carries `'ir` through a GAT
-        // (`Ref::Ref<T>`), which prevents the compiler from inferring
-        // covariance automatically. The bump arena that backs the IR is
-        // owned by `self._bump`, so the data is live for at least `'ir`.
-        unsafe { std::mem::transmute::<RawIrRef<'static>, RawIrRef<'ir>>(self.ir) }
-    }
-}
-
 impl DisassemblerContext for Evaluator {
     fn get_code(&self) -> &[u8] {
         &self.code.bytecode
     }
 
-    #[allow(clippy::unwrap_used)]
     fn resolve_string(&self, id: u32) -> &str {
-        let id = string_interner::symbol::SymbolU32::try_from_usize(id as usize).unwrap();
-        self.runtime.strings.resolve(id).unwrap()
+        let id = string_interner::symbol::SymbolU32::try_from_usize(id as usize)
+            .expect("invalid string id");
+        self.runtime.strings.resolve(id).expect("invalid string id")
     }
 }

fix/src/logging.rs

@@ -5,7 +5,7 @@ use tracing_subscriber::layer::SubscriberExt;
 use tracing_subscriber::util::SubscriberInitExt;
 use tracing_subscriber::{EnvFilter, Layer, fmt};
 
-pub fn init_logging() {
+pub fn init_logging() -> Result<(), miette::InstallError> {
     let is_terminal = std::io::stderr().is_terminal();
     let show_time = env::var("NIX_JS_LOG_TIME")
         .map(|v| v == "1" || v.to_lowercase() == "true")
@@ -32,10 +32,10 @@ pub fn init_logging() {
         .with(fmt_layer)
         .init();
 
-    init_miette_handler();
+    init_miette_handler()
 }
 
-fn init_miette_handler() {
+fn init_miette_handler() -> Result<(), miette::InstallError> {
     let is_terminal = std::io::stderr().is_terminal();
     miette::set_hook(Box::new(move |_| {
         Box::new(
@@ -46,5 +46,4 @@ fn init_miette_handler() {
                 .build(),
         )
     }))
-    .ok();
 }

fix/src/main.rs

@@ -20,33 +20,49 @@ struct Cli {
 enum Command {
     Compile {
         #[clap(flatten)]
-        source: ExprSource,
+        source: ExprSourceArgs,
         #[arg(long)]
         silent: bool,
     },
     Eval {
         #[clap(flatten)]
-        source: ExprSource,
+        source: ExprSourceArgs,
     },
     Repl,
 }
 
 #[derive(Args)]
 #[group(required = true, multiple = false)]
-struct ExprSource {
+struct ExprSourceArgs {
     #[clap(short, long)]
     expr: Option<String>,
     #[clap(short, long)]
     file: Option<PathBuf>,
 }
 
+enum ExprSource {
+    Expr(String),
+    File(PathBuf),
+}
+
+#[expect(
+    clippy::unreachable,
+    reason = "clap's arg group guarantees exactly one of --expr/--file is set"
+)]
+impl From<ExprSourceArgs> for ExprSource {
+    fn from(args: ExprSourceArgs) -> Self {
+        match (args.expr, args.file) {
+            (Some(expr), None) => ExprSource::Expr(expr),
+            (None, Some(file)) => ExprSource::File(file),
+            _ => unreachable!(),
+        }
+    }
+}
+
 fn run_compile(eval: &mut Evaluator, src: ExprSource, silent: bool) -> Result<()> {
-    let src = if let Some(expr) = src.expr {
-        Source::new_eval(expr)?
-    } else if let Some(file) = src.file {
-        Source::new_file(file)?
-    } else {
-        unreachable!()
+    let src = match src {
+        ExprSource::Expr(expr) => Source::new_eval(expr)?,
+        ExprSource::File(file) => Source::new_file(file)?,
     };
     match eval.compile_bytecode(src) {
         Ok(ip) => {
@@ -63,12 +79,9 @@ fn run_compile(eval: &mut Evaluator, src: ExprSource, silent: bool) -> Result<()
 }
 
 fn run_eval(eval: &mut Evaluator, src: ExprSource) -> Result<()> {
-    let src = if let Some(expr) = src.expr {
-        Source::new_eval(expr)?
-    } else if let Some(file) = src.file {
-        Source::new_file(file)?
-    } else {
-        unreachable!()
+    let src = match src {
+        ExprSource::Expr(expr) => Source::new_eval(expr)?,
+        ExprSource::File(file) => Source::new_file(file)?,
     };
     match eval.eval_deep(src) {
         Ok(value) => {
@@ -93,7 +106,9 @@ fn run_repl(eval: &mut Evaluator) -> Result<()> {
                 if line.trim().is_empty() {
                     continue;
                 }
-                let _ = rl.add_history_entry(line.as_str());
+                if let Err(err) = rl.add_history_entry(line.as_str()) {
+                    eprintln!("[WARN] Failed to add history entry: {err}");
+                }
                 if let Some([Some(_), Some(ident), Some(rest)]) = RE.exec(&line) {
                     if let Some(expr) = rest.strip_prefix('=') {
                         let expr = expr.trim_start();
@@ -137,15 +152,15 @@ fn run_repl(eval: &mut Evaluator) -> Result<()> {
 }
 
 fn main() -> Result<()> {
-    fix::logging::init_logging();
+    fix::logging::init_logging()?;
 
     let cli = Cli::parse();
 
     let mut eval = Evaluator::new();
 
     match cli.command {
-        Command::Compile { source, silent } => run_compile(&mut eval, source, silent),
-        Command::Eval { source } => run_eval(&mut eval, source),
+        Command::Compile { source, silent } => run_compile(&mut eval, source.into(), silent),
+        Command::Eval { source } => run_eval(&mut eval, source.into()),
         Command::Repl => run_repl(&mut eval),
     }
 }

fix/tests/tests/derivation.rs

@@ -1,4 +1,4 @@
-use fix_common::Value;
+use fix_lang::Value;
 
 use crate::utils::{eval_deep, eval_deep_result};
 
@@ -402,7 +402,6 @@ fn fixed_output_sha256_flat() {
 
 #[test_log::test]
 fn fixed_output_missing_hashalgo() {
-    assert!(
     eval_deep_result(
         r#"derivation {
             name = "default";
@@ -411,8 +410,7 @@ fn fixed_output_missing_hashalgo() {
             outputHash = "0000000000000000000000000000000000000000000000000000000000000000";
         }"#,
     )
-        .is_err()
-    );
+    .unwrap_err();
 }
 
 #[test_log::test]

fix/tests/tests/io_operations.rs

@@ -1,6 +1,6 @@
 use fix::Evaluator;
-use fix_common::Value;
 use fix_error::Source;
+use fix_lang::Value;
 
 use crate::utils::{eval, eval_result};
 
@@ -350,7 +350,7 @@ fn read_dir_nonexistent_fails() {
     let expr = r#"builtins.readDir "/nonexistent/directory""#;
     let result = eval_result(expr);
 
-    assert!(result.is_err());
+    result.unwrap_err();
 }
 
 #[test_log::test]

fix/tests/tests/lang.rs

@@ -3,8 +3,9 @@
 use std::path::PathBuf;
 
 use fix::Evaluator;
-use fix_common::Value;
 use fix_error::{Source, SourceType};
+use fix_lang::Value;
+use serial_test::serial;
 
 fn get_lang_dir() -> PathBuf {
     PathBuf::from(env!("CARGO_MANIFEST_DIR")).join("tests/tests/lang")
@@ -160,9 +161,14 @@ mod okay {
     eval_okay_test!(getattrpos);
     eval_okay_test!(getattrpos_functionargs);
     eval_okay_test!(getattrpos_undefined);
-    eval_okay_test!(getenv, || {
+    eval_okay_test!(
+        #[serial(env)]
+        getenv,
+        || {
+            // SAFETY: guarded with #[serial_test::serial]
             unsafe { std::env::set_var("TEST_VAR", "foo") };
-    });
+        }
+    );
     eval_okay_test!(groupBy);
     eval_okay_test!(r#if);
     eval_okay_test!(ind_string);
@@ -194,11 +200,16 @@ mod okay {
     eval_okay_test!(partition);
     eval_okay_test!(path);
     eval_okay_test!(pathexists);
-    eval_okay_test!(path_string_interpolation, || {
+    eval_okay_test!(
+        #[serial(env)]
+        path_string_interpolation,
+        || {
+            // SAFETY: guarded with #[serial_test::serial]
             unsafe {
                 std::env::set_var("HOME", "/fake-home");
             }
-    });
+        }
+    );
     eval_okay_test!(patterns);
     eval_okay_test!(print);
     eval_okay_test!(readDir);

fix/tests/tests/main.rs

@@ -1,3 +1,11 @@
+#![allow(clippy::allow_attributes_without_reason)]
+#![allow(
+    dead_code,
+    clippy::unwrap_used,
+    clippy::unwrap_in_result,
+    clippy::panic
+)]
+
 mod derivation;
 mod findfile;
 mod io_operations;

fix/tests/tests/string_context.rs

@@ -1,5 +1,5 @@
 use fix::Evaluator;
-use fix_common::Value;
+use fix_lang::Value;
 
 use crate::utils::eval_result;
 
@@ -348,7 +348,7 @@ fn substring_zero_length_empty_value() {
 }
 
 #[test_log::test]
-#[allow(non_snake_case)]
+#[expect(non_snake_case)]
 fn concatStringsSep_preserves_context() {
     let result = eval(
         r#"
@@ -365,7 +365,7 @@ fn concatStringsSep_preserves_context() {
 }
 
 #[test_log::test]
-#[allow(non_snake_case)]
+#[expect(non_snake_case)]
 fn concatStringsSep_merges_contexts() {
     let result = eval(
         r#"
@@ -383,7 +383,7 @@ fn concatStringsSep_merges_contexts() {
 }
 
 #[test_log::test]
-#[allow(non_snake_case)]
+#[expect(non_snake_case)]
 fn concatStringsSep_separator_has_context() {
     let result = eval(
         r#"
@@ -398,7 +398,7 @@ fn concatStringsSep_separator_has_context() {
 }
 
 #[test_log::test]
-#[allow(non_snake_case)]
+#[expect(non_snake_case)]
 fn replaceStrings_input_context_preserved() {
     let result = eval(
         r#"
@@ -413,7 +413,7 @@ fn replaceStrings_input_context_preserved() {
 }
 
 #[test_log::test]
-#[allow(non_snake_case)]
+#[expect(non_snake_case)]
 fn replaceStrings_replacement_context_collected() {
     let result = eval(
         r#"
@@ -428,7 +428,7 @@ fn replaceStrings_replacement_context_collected() {
 }
 
 #[test_log::test]
-#[allow(non_snake_case)]
+#[expect(non_snake_case)]
 fn replaceStrings_merges_contexts() {
     let result = eval(
         r#"
@@ -446,7 +446,7 @@ fn replaceStrings_merges_contexts() {
 }
 
 #[test_log::test]
-#[allow(non_snake_case)]
+#[expect(non_snake_case)]
 fn replaceStrings_lazy_evaluation_context() {
     let result = eval(
         r#"
@@ -461,7 +461,7 @@ fn replaceStrings_lazy_evaluation_context() {
 }
 
 #[test_log::test]
-#[allow(non_snake_case)]
+#[expect(non_snake_case)]
 fn baseNameOf_preserves_context() {
     let result = eval(
         r#"

fix/tests/tests/utils.rs

@@ -1,8 +1,6 @@
-#![allow(dead_code)]
-
 use fix::Evaluator;
-use fix_common::Value;
 use fix_error::{Result, Source};
+use fix_lang::Value;
 
 pub fn eval(expr: &str) -> Value {
     Evaluator::new()

flake.lock

@@ -1,64 +1,5 @@
 {
   "nodes": {
-    "blueprint": {
-      "inputs": {
-        "nixpkgs": [
-          "llm-agents",
-          "nixpkgs"
-        ],
-        "systems": [
-          "llm-agents",
-          "systems"
-        ]
-      },
-      "locked": {
-        "lastModified": 1776249299,
-        "narHash": "sha256-Dt9t1TGRmJFc0xVYhttNBD6QsAgHOHCArqGa0AyjrJY=",
-        "owner": "numtide",
-        "repo": "blueprint",
-        "rev": "56131e8628f173d24a27f6d27c0215eff57e40dd",
-        "type": "github"
-      },
-      "original": {
-        "owner": "numtide",
-        "repo": "blueprint",
-        "type": "github"
-      }
-    },
-    "bun2nix": {
-      "inputs": {
-        "flake-parts": [
-          "llm-agents",
-          "flake-parts"
-        ],
-        "nixpkgs": [
-          "llm-agents",
-          "nixpkgs"
-        ],
-        "systems": [
-          "llm-agents",
-          "systems"
-        ],
-        "treefmt-nix": [
-          "llm-agents",
-          "treefmt-nix"
-        ]
-      },
-      "locked": {
-        "lastModified": 1778445566,
-        "narHash": "sha256-oQvcadh2BCkrog+SGrG6YffKJrveYpjj3TdQJWaKhaM=",
-        "owner": "nix-community",
-        "repo": "bun2nix",
-        "rev": "2499dedd70744dba1815875b854818a3019e9e4c",
-        "type": "github"
-      },
-      "original": {
-        "owner": "nix-community",
-        "ref": "staging-2.1.0",
-        "repo": "bun2nix",
-        "type": "github"
-      }
-    },
     "fenix": {
       "inputs": {
         "nixpkgs": [
@@ -67,11 +8,11 @@
         "rust-analyzer-src": "rust-analyzer-src"
       },
       "locked": {
-        "lastModified": 1778919578,
-        "narHash": "sha256-+z+jgTly48gsAiX8rOe/vs8C/2G4vdCpcEtqMJUpFqw=",
+        "lastModified": 1784017020,
+        "narHash": "sha256-49WO85egjNtN1vMgJ3zUjDh5IqO+ou4zZY80WQ6EKGg=",
         "owner": "nix-community",
         "repo": "fenix",
-        "rev": "ecd6d4ff22cfdb1339b2915455a2ff4dc85bf52e",
+        "rev": "fa2a0be0f712d7147d1677d33d15ea7b0589cdb4",
         "type": "github"
       },
       "original": {
@@ -94,59 +35,13 @@
         "url": "https://git.lix.systems/lix-project/flake-compat/archive/main.tar.gz"
       }
     },
-    "flake-parts": {
-      "inputs": {
-        "nixpkgs-lib": [
-          "llm-agents",
-          "nixpkgs"
-        ]
-      },
-      "locked": {
-        "lastModified": 1778716662,
-        "narHash": "sha256-m1Yf0wZ8j1OHjTc2UwHwyQRSnNeSgLJOd7q5Y45hzi4=",
-        "owner": "hercules-ci",
-        "repo": "flake-parts",
-        "rev": "f7c1a2d347e4c52d5fb8d10cb4d94b5884e546fb",
-        "type": "github"
-      },
-      "original": {
-        "owner": "hercules-ci",
-        "repo": "flake-parts",
-        "type": "github"
-      }
-    },
-    "llm-agents": {
-      "inputs": {
-        "blueprint": "blueprint",
-        "bun2nix": "bun2nix",
-        "flake-parts": "flake-parts",
-        "nixpkgs": [
-          "nixpkgs"
-        ],
-        "systems": "systems",
-        "treefmt-nix": "treefmt-nix"
-      },
-      "locked": {
-        "lastModified": 1778929997,
-        "narHash": "sha256-iAfbBUHBbR0N4DFqFWr4Jtmpc1YcOK7kpVM4f0MK1V8=",
-        "owner": "numtide",
-        "repo": "llm-agents.nix",
-        "rev": "0da8f0313c9f68c155e0932f880fc1913e7be846",
-        "type": "github"
-      },
-      "original": {
-        "owner": "numtide",
-        "repo": "llm-agents.nix",
-        "type": "github"
-      }
-    },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1778443072,
-        "narHash": "sha256-zi7/fsqM/kFdNuED//4WOCUtezGtKKqRNORjMvfwjnA=",
+        "lastModified": 1784007870,
+        "narHash": "sha256-djcLt/JJphyNt4eDY9XTly+/WbCK5lqWq9lSgCmJkkQ=",
         "owner": "nixos",
         "repo": "nixpkgs",
-        "rev": "da5ad661ba4e5ef59ba743f0d112cbc30e474f32",
+        "rev": "18b9261cb3294b6d2a06d03f96872827b8fe2698",
         "type": "github"
       },
       "original": {
@@ -160,18 +55,17 @@
       "inputs": {
         "fenix": "fenix",
         "flake-compat": "flake-compat",
-        "llm-agents": "llm-agents",
         "nixpkgs": "nixpkgs"
       }
     },
     "rust-analyzer-src": {
       "flake": false,
       "locked": {
-        "lastModified": 1778854817,
-        "narHash": "sha256-iG+VuMy8W585geVVCUd7pR025WsY3ZkgSv5Yt5bxDmQ=",
+        "lastModified": 1783975201,
+        "narHash": "sha256-oyHWTfKWk06nTynCO8ByEAx/KEARvOOyTVnwinOmK3Q=",
         "owner": "rust-lang",
         "repo": "rust-analyzer",
-        "rev": "1a68212c5683555ad80f0eab71db9715c6d52145",
+        "rev": "63a6f0d4bcfd3bbcf36383fcbcbcd93456ed1653",
         "type": "github"
       },
       "original": {
@@ -180,42 +74,6 @@
         "repo": "rust-analyzer",
         "type": "github"
       }
-    },
-    "systems": {
-      "locked": {
-        "lastModified": 1681028828,
-        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
-        "owner": "nix-systems",
-        "repo": "default",
-        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
-        "type": "github"
-      },
-      "original": {
-        "owner": "nix-systems",
-        "repo": "default",
-        "type": "github"
-      }
-    },
-    "treefmt-nix": {
-      "inputs": {
-        "nixpkgs": [
-          "llm-agents",
-          "nixpkgs"
-        ]
-      },
-      "locked": {
-        "lastModified": 1775636079,
-        "narHash": "sha256-pc20NRoMdiar8oPQceQT47UUZMBTiMdUuWrYu2obUP0=",
-        "owner": "numtide",
-        "repo": "treefmt-nix",
-        "rev": "790751ff7fd3801feeaf96d7dc416a8d581265ba",
-        "type": "github"
-      },
-      "original": {
-        "owner": "numtide",
-        "repo": "treefmt-nix",
-        "type": "github"
-      }
     }
   },
   "root": "root",

flake.nix

@@ -3,17 +3,13 @@
     nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
     fenix.url = "github:nix-community/fenix";
     fenix.inputs.nixpkgs.follows = "nixpkgs";
-    llm-agents = {
-      url = "github:numtide/llm-agents.nix";
-      inputs.nixpkgs.follows = "nixpkgs";
-    };
     flake-compat = {
       url = "https://git.lix.systems/lix-project/flake-compat/archive/main.tar.gz";
       flake = false;
     };
   };
   outputs =
-    inputs@{ nixpkgs, fenix, ... }:
+    { nixpkgs, fenix, ... }:
     let
       forAllSystems = nixpkgs.lib.genAttrs nixpkgs.lib.systems.flakeExposed;
     in
@@ -24,36 +20,11 @@
           pkgs = import nixpkgs {
             inherit system;
             config.allowUnfree = true;
+            overlays = [ fenix.overlays.default ];
           };
-          llm-agents = inputs.llm-agents.packages.${pkgs.stdenv.hostPlatform.system};
         in
         {
-          default = pkgs.mkShell {
-            packages = with pkgs; [
-              (fenix.packages.${system}.latest.withComponents [
-                "cargo"
-                "clippy"
-                "rust-src"
-                "rustc"
-                "rustfmt"
-                "rust-analyzer"
-              ])
-              cargo-machete
-              cargo-bloat
-              lldb
-              valgrind
-              kdePackages.kcachegrind
-              hyperfine
-              just
-              samply
-              tokei
-
-              llm-agents.codex
-              llm-agents.claude-code
-              llm-agents.opencode
-              llm-agents.forge
-            ];
-          };
+          default = import ./devShell.nix { inherit pkgs; };
         }
       );
     };

shell.nix

@@ -1,16 +0,0 @@
-let
-  lockFile = builtins.fromJSON (builtins.readFile ./flake.lock);
-  flake-compat-node = lockFile.nodes.${lockFile.nodes.root.inputs.flake-compat};
-  flake-compat = builtins.fetchTarball {
-    inherit (flake-compat-node.locked) url;
-    sha256 = flake-compat-node.locked.narHash;
-  };
-
-  flake = (
-    import flake-compat {
-      src = ./.;
-      copySourceTreeToStore = false;
-    }
-  );
-in
-  flake.shellNix