runtime, macros: unify NaN-boxed value API under ValueVariant trait

Cargo.lock

@@ -513,6 +513,16 @@ dependencies = [
  "string-interner",
 ]
 
+[[package]]
+name = "fix-macros"
+version = "0.1.0"
+dependencies = [
+ "manyhow",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "fix-runtime"
 version = "0.1.0"
@@ -520,6 +530,7 @@ dependencies = [
  "fix-bytecode",
  "fix-error",
  "fix-lang",
+ "fix-macros",
  "gc-arena",
  "hashbrown 0.16.1",
  "smallvec",
@@ -747,6 +758,29 @@ version = "0.4.29"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5e5032e24019045c762d3c0f28f5b6b8bbf38563a65908389bf7978758920897"
 
+[[package]]
+name = "manyhow"
+version = "0.11.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b33efb3ca6d3b07393750d4030418d594ab1139cee518f0dc88db70fec873587"
+dependencies = [
+ "manyhow-macros",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "manyhow-macros"
+version = "0.11.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "46fce34d199b78b6e6073abf984c9cf5fd3e9330145a93ee0738a7443e371495"
+dependencies = [
+ "proc-macro-utils",
+ "proc-macro2",
+ "quote",
+]
+
 [[package]]
 name = "matchers"
 version = "0.2.0"
@@ -995,6 +1029,17 @@ dependencies = [
  "toml_edit",
 ]
 
+[[package]]
+name = "proc-macro-utils"
+version = "0.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "eeaf08a13de400bc215877b5bdc088f241b12eb42f0a548d3390dc1c56bb7071"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "smallvec",
+]
+
 [[package]]
 name = "proc-macro2"
 version = "1.0.106"
@@ -1006,9 +1051,9 @@ dependencies = [
 
 [[package]]
 name = "quote"
-version = "1.0.45"
+version = "1.0.46"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "41f2619966050689382d2b44f664f4bc593e129785a36d6ee376ddf37259b924"
+checksum = "dfbc457d0c7a0759a614551b11a6409e5951f6c7537be1f1b7682b9ae9230368"
 dependencies = [
  "proc-macro2",
 ]
@@ -1275,9 +1320,9 @@ checksum = "b7401a30af6cb5818bb64852270bb722533397edcfc7344954a38f420819ece2"
 
 [[package]]
 name = "syn"
-version = "2.0.117"
+version = "2.0.118"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e665b8803e7b1d2a727f4023456bbbbe74da67099c585258af0ad9c5013b9b99"
+checksum = "1b9ae57f904213ebb649ce6895b8a66c66f0203b9319718f69a5612a065b1422"
 dependencies = [
  "proc-macro2",
  "quote",

Cargo.toml

@@ -6,6 +6,7 @@ members = [
   "fix-compiler",
   "fix-error",
   "fix-lang",
+  "fix-macros",
   "fix-runtime",
   "fix-vm",
 ]

fix-bytecode/src/disassembler.rs

@@ -2,7 +2,7 @@ use std::fmt::Write;
 
 use colored::Colorize as _;
 
-use crate::{InstructionPtr, Op, OperandType, Continuation};
+use crate::{Continuation, InstructionPtr, Op, OperandType};
 
 pub trait DisassemblerContext {
     fn resolve_string(&self, id: u32) -> &str;

fix-compiler/src/context.rs

@@ -1,5 +1,5 @@
 use bumpalo::Bump;
-use fix_bytecode::{Const, InstructionPtr, Op, Continuation};
+use fix_bytecode::{Const, Continuation, InstructionPtr, Op};
 use fix_error::{Error, Result, Source};
 use fix_lang::{StringId, Symbol};
 use fix_runtime::{StaticValue, VmCode, VmRuntimeCtx};
@@ -148,16 +148,20 @@ impl<'a, R: VmRuntimeCtx> BytecodeContext for CompilerCtx<'a, R> {
     fn add_constant(&mut self, val: Const) -> u32 {
         use Const::*;
         let val = match val {
-            Smi(x) => StaticValue::new_inline(x),
+            Smi(x) => StaticValue::new(x),
-            Float(x) => StaticValue::new_float(x),
+            Float(x) => StaticValue::new(x),
-            Bool(x) => StaticValue::new_inline(x),
+            Bool(x) => StaticValue::new(x),
-            String(x) => StaticValue::new_inline(x),
+            String(x) => StaticValue::new(x),
-            Path(x) => StaticValue::new_inline(fix_runtime::Path(x)),
+            Path(x) => StaticValue::new(fix_runtime::Path(x)),
             PrimOp {
                 id,
                 arity,
                 dispatch_ip,
-            } => StaticValue::new_primop(id, arity, dispatch_ip),
+            } => StaticValue::new(fix_runtime::PrimOp {
+                id,
+                arity,
+                dispatch_ip,
+            }),
             Null => StaticValue::default(),
         };
         self.runtime.add_const(val)

fix-compiler/src/lib.rs

@@ -1,4 +1,4 @@
-use fix_bytecode::{Const, InstructionPtr, Op, OperandType, Continuation};
+use fix_bytecode::{Const, Continuation, InstructionPtr, Op, OperandType};
 use fix_lang::{BUILTINS, StringId};
 use hashbrown::HashMap;
 use rnix::TextRange;

fix-macros/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "fix-macros"
+version = "0.1.0"
+edition = "2024"
+
+[lib]
+proc-macro = true
+
+[dependencies]
+manyhow = "0.11"
+proc-macro2 = "1.0"
+quote = "1.0"
+syn = { version = "2.0", features = ["full", "visit"] }

fix-macros/src/lib.rs

@@ -0,0 +1,39 @@
+extern crate proc_macro;
+
+// 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-runtime/Cargo.toml

@@ -13,3 +13,4 @@ string-interner = { workspace = true }
 fix-bytecode = { path = "../fix-bytecode" }
 fix-error = { path = "../fix-error" }
 fix-lang = { path = "../fix-lang" }
+fix-macros = { path = "../fix-macros" }

fix-runtime/src/forced.rs

@@ -1,9 +1,9 @@
 use fix_lang::StringId;
-use gc_arena::{Gc, Mutation};
+use gc_arena::Mutation;
 
 use crate::{
     AttrSet, Break, BytecodeReader, Closure, List, Machine, NixNum, NixString, NixType, Null,
-    PrimOp, PrimOpApp, Step, StrictValue,
+    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 {
+macro_rules! impl_forced {
-    ($($ty:ty => $nix_ty:expr),* $(,)?) => {
+    ($($ty:ty),* $(,)?) => {
         $(
-        impl<'gc> Forced<'gc> for $ty {
+        impl<'gc> Forced<'gc> for <$ty as ValueVariant>::Ty<'gc> {
             const WIDTH: usize = 1;
 
             #[inline(always)]
@@ -63,8 +63,8 @@ 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::<$ty>().is_none() {
+                if v.downcast::<$ty>().is_none() {
-                    let _: Step = m.finish_type_err($nix_ty, v.ty());
+                    let _: Step = m.finish_type_err(<$ty as ValueVariant>::TYPE, v.ty());
                     return Step::Break(Break::Done);
                 }
                 Step::Continue(())
@@ -73,7 +73,7 @@ macro_rules! impl_forced_inline {
             #[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 {
+impl_forced! {
-    ($($ty:ty => $nix_ty:expr),* $(,)?) => {
+    i32,
-        $(
+    bool,
-        impl<'gc> Forced<'gc> for Gc<'gc, $ty> {
+    Null,
-            const WIDTH: usize = 1;
+    StringId,
-
+    PrimOp,
-            #[inline(always)]
+    i64,
-            fn force_and_check<M: Machine<'gc>>(
+    NixString,
-                m: &mut M,
+    AttrSet<'gc>,
-                reader: &mut BytecodeReader<'_>,
+    List<'gc>,
-                mc: &Mutation<'gc>,
+    Closure<'gc>,
-                base_depth: usize,
+    PrimOpApp<'gc>,
-                resume_pc: usize,
-            ) -> Step {
-                m.force_slot_to_pc(base_depth, reader, mc, resume_pc)?;
-                let v = m.peek_forced(base_depth);
-                if v.as_gc::<$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<'gc> Forced<'gc> for NixNum {
@@ -145,7 +108,7 @@ 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() {
+        if v.downcast_num().is_none() {
             let _: Step = m.finish_type_err(NixType::Int, v.ty());
             return Step::Break(Break::Done);
         }
@@ -155,7 +118,7 @@ impl<'gc> Forced<'gc> for NixNum {
     #[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")
     }
 }
@@ -173,7 +136,7 @@ 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() {
+        if v.downcast::<f64>().is_none() {
             let _: Step = m.finish_type_err(NixType::Float, v.ty());
             return Step::Break(Break::Done);
         }
@@ -183,7 +146,7 @@ impl<'gc> Forced<'gc> for f64 {
     #[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

@@ -44,10 +44,10 @@ pub trait VmRuntimeCtxExt: VmRuntimeCtx {
 
 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())
         }
     }
 
@@ -56,7 +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)
@@ -67,9 +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())
@@ -77,7 +77,7 @@ 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()
@@ -96,24 +96,24 @@ pub(crate) trait ConvertValueWithSeen: VmRuntimeCtx {
 impl<T: VmRuntimeCtx> ConvertValueWithSeen for T {
     fn convert_value_with_seen(&self, val: Value, seen: &mut HashSet<u64>) -> fix_lang::Value {
         use fix_lang::Value;
-        if let Some(i) = val.as_inline::<i32>() {
+        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());
@@ -128,7 +128,7 @@ impl<T: VmRuntimeCtx> ConvertValueWithSeen for T {
                 map.insert(fix_lang::Symbol::from(key), converted);
             }
             Value::AttrSet(fix_lang::AttrSet::new(map))
-        } else if let Some(list) = val.as_gc::<List>() {
+        } else if let Some(list) = val.downcast::<List>() {
             let bits = val.to_bits();
             if list.inner.borrow().is_empty() {
                 return Value::List(Default::default());
@@ -146,16 +146,16 @@ impl<T: VmRuntimeCtx> ConvertValueWithSeen for T {
             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>() {
+        } else if let Some(primop) = val.downcast::<PrimOp>() {
             let name = BUILTINS[primop.id as usize].0;
             Value::PrimOp(name.strip_prefix("__").unwrap_or(name))
-        } else if let Some(app) = val.as_gc::<PrimOpApp>() {
+        } else if let Some(app) = val.downcast::<PrimOpApp>() {
             let name = BUILTINS[app.primop.id as usize].0;
             Value::PrimOpApp(name.strip_prefix("__").unwrap_or(name))
         } else {

fix-runtime/src/resolve.rs

@@ -18,16 +18,21 @@ pub fn resolve_operand<'gc, M: Machine<'gc>>(
     use OperandData::*;
     match *op {
         Const(id) => ctx.get_const(id).into(),
-        BigInt(val) => Value::new_gc(Gc::new(mc, val)),
+        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(),
+        BuiltinConst(id) => m
+            .builtins()
+            .downcast::<AttrSet>()
+            .unwrap()
+            .lookup(id)
+            .unwrap(),
         Builtins => m.builtins(),
         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");
+            let attrs = scope.downcast::<AttrSet>().expect("scope must be attrset");
             #[allow(clippy::unwrap_used)]
             attrs.lookup(name).expect("scoped binding not found")
         }

fix-runtime/src/value.rs

@@ -19,33 +19,84 @@ mod private {
     pub trait Cealed {}
 }
 
+pub trait ValueVariant: private::Cealed {
+    type Ty<'gc>: 'gc;
+    const TYPE: NixType;
+    fn is_value(value: &Value<'_>) -> bool;
+    /// # Safety
+    ///
+    /// [`Self::is_value`] must hold for `value`.
+    unsafe fn from_raw<'gc>(value: &Value<'gc>) -> Self::Ty<'gc>;
+}
+
 /// # Safety
 ///
-/// [`Self::TAG`] must be unique among all implementors.
+/// Each implementor must round-trip through [`Self::to_raw_box`] /
-unsafe trait Storable: private::Cealed {
+/// [`Self::from_raw_box`] and must be the sole owner of its NaN-boxed
-    const TAG: RawTag;
+/// representation (tagged payload or float).
+pub(crate) unsafe trait Storable: private::Cealed {
+    fn to_raw_box(self) -> RawBox;
+    /// # Safety
+    ///
+    /// `raw` must represent a valid `Self`.
+    unsafe fn from_raw_box(raw: &RawBox) -> Self;
 }
-trait InlineStorable: Storable + RawStore {}
-trait GcStorable: Storable {}
 
 macro_rules! define_value_types {
     (
-        inline { $($itype:ty => $itag:expr, $iname:literal;)* }
+        inline { $($itype:ty => $itag:path, $ity:path, $iname:literal;)* }
-        gc { $($gtype:ty => $gtag:expr, $gname:literal;)* }
+        gc { $($gtype:ty => $gtag:path, $gty:path, $gname:literal;)* }
     ) => {
         $(
         unsafe impl Storable for $itype {
-            const TAG: RawTag = $itag;
+            fn to_raw_box(self) -> RawBox {
+                RawBox::from_value(RawValue::store($itag, self))
+            }
+            unsafe fn from_raw_box(raw: &RawBox) -> Self {
+                unsafe { <Self as RawStore>::from_val(raw.value().unwrap_unchecked()) }
+            }
         }
-        impl InlineStorable for $itype {}
         impl private::Cealed for $itype {}
+        impl ValueVariant for $itype {
+            type Ty<'gc> = $itype;
+            const TYPE: NixType = $ity;
+            #[inline(always)]
+            fn is_value(value: &Value<'_>) -> bool {
+                value.raw.tag() == Some($itag)
+            }
+            #[inline(always)]
+            unsafe fn from_raw<'gc>(value: &Value<'gc>) -> Self::Ty<'gc> {
+                unsafe { <$itype as Storable>::from_raw_box(&value.raw) }
+            }
+        }
         )*
         $(
-        unsafe impl Storable for $gtype {
+        unsafe impl Storable for Gc<'_, $gtype> {
-            const TAG: RawTag = $gtag;
+            fn to_raw_box(self) -> RawBox {
+                RawBox::from_value(RawValue::store($gtag, Gc::as_ptr(self)))
             }
-        impl GcStorable for $gtype {}
+            unsafe fn from_raw_box(raw: &RawBox) -> Self {
+                unsafe { Gc::from_ptr(<*mut $gtype as RawStore>::from_val(raw.value().unwrap_unchecked())) }
+            }
+        }
+        impl private::Cealed for Gc<'_, $gtype> {}
         impl private::Cealed for $gtype {}
+        impl ValueVariant for $gtype {
+            type Ty<'gc> = Gc<'gc, fix_macros::unelide_lifetimes!('gc; $gtype)>;
+            const TYPE: NixType = $gty;
+            #[inline(always)]
+            fn is_value(value: &Value<'_>) -> bool {
+                value.raw.tag() == Some($gtag)
+            }
+            #[inline(always)]
+            unsafe fn from_raw<'gc>(value: &Value<'gc>) -> Self::Ty<'gc> {
+                unsafe {
+                    <Gc<'gc, fix_macros::unelide_lifetimes!('gc; $gtype)> as Storable>::from_raw_box(
+                        &value.raw,
+                    )
+                }
+            }
+        }
         )*
 
         const _: () = assert!(size_of::<Value<'static>>() == 8);
@@ -75,10 +126,10 @@ macro_rules! define_value_types {
             fn trace<T: Trace<'gc>>(&self, cc: &mut T) {
                 let Some(tag) = self.raw.tag() else { return };
                 match tag {
-                    $(<$gtype as Storable>::TAG => unsafe {
+                    $($gtag => unsafe {
-                        self.load_gc::<$gtype>().trace(cc)
+                        self.downcast::<$gtype>().unwrap_unchecked().trace(cc)
                     },)*
-                    $(<$itype as Storable>::TAG => (),)*
+                    $($itag => (),)*
                     _ => unreachable!("invalid value tag"),
                 }
             }
@@ -90,10 +141,10 @@ macro_rules! define_value_types {
                     None => write!(f, "Float({:?})", unsafe {
                         self.raw.float().unwrap_unchecked()
                     }),
-                    $(Some(<$itype as Storable>::TAG) => write!(f, "{}({:?})", $iname, unsafe {
+                    $(Some($itag) => write!(f, "{}({:?})", $iname, unsafe {
-                        self.as_inline::<$itype>().unwrap_unchecked()
+                        self.downcast::<$itype>().unwrap_unchecked()
                     }),)*
-                    $(Some(<$gtype as Storable>::TAG) =>
+                    $(Some($gtag) =>
                         write!(f, "{}(..)", $gname),)*
                     _ => unreachable!("invalid value tag"),
                 }
@@ -104,21 +155,45 @@ macro_rules! define_value_types {
 
 define_value_types! {
     inline {
-        i32 => RawTag::P1, "SmallInt";
+        i32 => RawTag::P1, NixType::Int, "SmallInt";
-        bool => RawTag::P2, "Bool";
+        bool => RawTag::P2, NixType::Bool, "Bool";
-        Null => RawTag::P3, "Null";
+        Null => RawTag::P3, NixType::Null, "Null";
-        StringId => RawTag::P4, "SmallString";
+        StringId => RawTag::P4, NixType::String, "SmallString";
-        PrimOp => RawTag::P5, "PrimOp";
+        PrimOp => RawTag::P5, NixType::PrimOp, "PrimOp";
-        Path => RawTag::P6, "Path";
+        Path => RawTag::P6, NixType::Path, "Path";
     }
     gc {
-        i64 => RawTag::P7, "BigInt";
+        i64 => RawTag::P7, NixType::Int, "BigInt";
-        NixString => RawTag::N1, "String";
+        NixString => RawTag::N1, NixType::String, "String";
-        AttrSet<'_> => RawTag::N2, "AttrSet";
+        AttrSet<'_> => RawTag::N2, NixType::AttrSet, "AttrSet";
-        List<'_> => RawTag::N3, "List";
+        List<'_> => RawTag::N3, NixType::List, "List";
-        Thunk<'_> => RawTag::N4, "Thunk";
+        Thunk<'_> => RawTag::N4, NixType::Thunk, "Thunk";
-        Closure<'_> => RawTag::N5, "Closure";
+        Closure<'_> => RawTag::N5, NixType::Closure, "Closure";
-        PrimOpApp<'_> => RawTag::N6, "PrimOpApp";
+        PrimOpApp<'_> => RawTag::N6, NixType::Closure, "PrimOpApp";
+    }
+}
+
+impl private::Cealed for f64 {}
+
+unsafe impl Storable for f64 {
+    fn to_raw_box(self) -> RawBox {
+        RawBox::from_float(self)
+    }
+    unsafe fn from_raw_box(raw: &RawBox) -> Self {
+        unsafe { raw.float().copied().unwrap_unchecked() }
+    }
+}
+
+impl ValueVariant for f64 {
+    type Ty<'gc> = f64;
+    const TYPE: NixType = NixType::Float;
+    #[inline(always)]
+    fn is_value(value: &Value<'_>) -> bool {
+        value.raw.is_float()
+    }
+    #[inline(always)]
+    unsafe fn from_raw<'gc>(value: &Value<'gc>) -> Self::Ty<'gc> {
+        unsafe { <f64 as Storable>::from_raw_box(&value.raw) }
     }
 }
 
@@ -135,33 +210,11 @@ 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()
@@ -170,80 +223,31 @@ impl<'gc> Value<'gc> {
 
 impl<'gc> Value<'gc> {
     #[inline]
-    pub fn new_float(val: f64) -> Self {
+    #[allow(private_bounds)]
+    pub fn new<T: Storable>(val: T) -> Self {
         Self {
-            raw: RawBox::from_float(val),
+            raw: val.to_raw_box(),
             _marker: PhantomData,
         }
     }
 
-    #[inline]
-    #[allow(private_bounds)]
-    pub fn new_inline<T: InlineStorable>(val: T) -> Self {
-        Self::from_raw_value(RawValue::store(T::TAG, val))
-    }
-
-    #[inline]
-    #[allow(private_bounds)]
-    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))
+            Value::new(Gc::new(mc, val))
-        }
-    }
-}
-
-impl<'gc> Value<'gc> {
-    #[inline]
-    pub fn is_float(self) -> bool {
-        self.raw.is_float()
-    }
-
-    #[inline]
-    #[allow(private_bounds)]
-    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]
-    #[allow(private_bounds)]
-    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
         }
     }
 
     #[inline]
-    #[allow(private_bounds)]
+    pub fn is<T: ValueVariant>(self) -> bool {
-    pub fn as_gc<T: GcStorable>(self) -> Option<Gc<'gc, T>> {
+        T::is_value(&self)
-        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
     }
+
+    #[inline]
+    pub fn downcast<T: ValueVariant>(self) -> Option<T::Ty<'gc>> {
+        self.is::<T>().then(|| unsafe { T::from_raw(&self) })
     }
 
     #[inline]
@@ -252,19 +256,19 @@ impl<'gc> Value<'gc> {
     }
 
     #[inline]
-    pub fn as_num(self) -> Option<NixNum> {
+    pub fn downcast_num(self) -> Option<NixNum> {
-        if let Some(i) = self.as_inline::<i32>() {
+        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))
@@ -273,7 +277,7 @@ impl<'gc> Value<'gc> {
 
     #[inline]
     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
@@ -305,30 +309,13 @@ impl<'gc> Value<'gc> {
     }
 
     #[inline]
-    #[allow(private_bounds)]
+    pub fn expect<T: ValueVariant>(self) -> Result<T::Ty<'gc>, NixType> {
-    pub fn expect_inline<T: InlineStorable>(self) -> Result<T, NixType> {
+        self.downcast::<T>().ok_or_else(|| self.ty())
-        self.as_inline::<T>().ok_or_else(|| self.ty())
-    }
-
-    #[inline]
-    #[allow(private_bounds)]
-    pub fn expect_gc<T: GcStorable>(self) -> Result<Gc<'gc, T>, NixType> {
-        self.as_gc::<T>().ok_or_else(|| self.ty())
     }
 
     #[inline]
     pub fn expect_num(self) -> Result<NixNum, NixType> {
-        self.as_num().ok_or_else(|| self.ty())
+        self.downcast_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())
     }
 }
 
@@ -345,41 +332,22 @@ impl<'gc> From<StaticValue> for Value<'gc> {
 }
 
 impl StaticValue {
-    #[inline]
-    pub fn new_float(val: f64) -> Self {
-        Self(Value::new_float(val))
-    }
     #[inline]
     #[allow(private_bounds)]
-    pub fn new_inline<T: InlineStorable>(val: T) -> Self {
+    pub fn new<T: Storable + 'static>(val: T) -> Self {
-        Self(Value::new_inline(val))
+        Self(Value::new(val))
     }
+
     #[inline]
-    pub fn new_primop(id: BuiltinId, arity: u8, dispatch_ip: u32) -> Self {
+    pub fn is<T: ValueVariant>(self) -> bool {
-        Self(Value::new_inline(PrimOp {
-            id,
-            arity,
-            dispatch_ip,
-        }))
-    }
-    #[inline]
-    pub fn is_float(self) -> bool {
-        self.0.is_float()
-    }
-    #[inline]
-    #[allow(private_bounds)]
-    pub fn is<T: InlineStorable>(self) -> bool {
         self.0.is::<T>()
     }
+
     #[inline]
-    pub fn as_float(self) -> Option<f64> {
+    pub fn downcast<T: ValueVariant>(self) -> Option<T::Ty<'static>> {
-        self.0.as_float()
+        self.0.downcast::<T>()
-    }
-    #[inline]
-    #[allow(private_bounds)]
-    pub fn as_inline<T: InlineStorable>(self) -> Option<T> {
-        self.0.as_inline::<T>()
     }
+
     #[inline]
     pub fn to_bits(self) -> u64 {
         self.0.raw.to_bits()

fix-vm/src/instructions/arithmetic.rs

@@ -28,7 +28,7 @@ pub(crate) fn op_add<'gc, M: Machine<'gc>>(
         let combined = format!("{ls}{rs}");
         let canon = canon_path_str(&combined);
         let sid = ctx.intern_string(canon);
-        m.push(Value::new_inline(fix_runtime::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)) {
@@ -39,7 +39,7 @@ pub(crate) fn op_add<'gc, M: Machine<'gc>>(
             mc,
             crate::NixString::with_context(format!("{ls}{rs}"), merged),
         );
-        m.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);
@@ -200,7 +200,7 @@ pub(crate) fn op_concat<'gc, M: Machine<'gc>>(
     let mut items = smallvec::SmallVec::new();
     items.extend_from_slice(&l.inner.borrow());
     items.extend_from_slice(&r.inner.borrow());
-    m.push(Value::new_gc(Gc::new(
+    m.push(Value::new(Gc::new(
         mc,
         crate::List {
             inner: RefLock::new(items),
@@ -216,7 +216,7 @@ pub(crate) fn op_update<'gc, M: Machine<'gc>>(
     mc: &Mutation<'gc>,
 ) -> Step {
     let (l, r) = m.force_and_retry::<(Gc<AttrSet>, Gc<AttrSet>)>(reader, mc)?;
-    m.push(Value::new_gc(l.merge(&r, mc)));
+    m.push(Value::new(l.merge(&r, mc)));
     Step::Continue(())
 }
 
@@ -229,7 +229,7 @@ pub(crate) fn op_neg<'gc, M: Machine<'gc>>(
     let rhs = m.force_and_retry::<NixNum>(reader, mc)?;
     match rhs {
         NixNum::Int(int) => m.push(Value::make_int(-int, mc)),
-        NixNum::Float(float) => m.push(Value::new_float(-float)),
+        NixNum::Float(float) => m.push(Value::new(-float)),
     }
     Step::Continue(())
 }
@@ -241,7 +241,7 @@ pub(crate) fn op_not<'gc, M: Machine<'gc>>(
     mc: &Mutation<'gc>,
 ) -> Step {
     let rhs = m.force_and_retry::<bool>(reader, mc)?;
-    m.push(Value::new_inline(!rhs));
+    m.push(Value::new(!rhs));
     Step::Continue(())
 }
 
@@ -263,17 +263,17 @@ fn compare_values_inner<'gc, M: Machine<'gc>>(
                 a.partial_cmp(&(b as f64)).unwrap_or(Ordering::Less)
             }
         };
-        m.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)) {
-        m.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);
-        m.push(Value::new_inline(pred(a.cmp(b))));
+        m.push(Value::new(pred(a.cmp(b))));
         return Ok(());
     }
     // TODO: compare other types
@@ -285,12 +285,12 @@ fn compare_values_inner<'gc, M: Machine<'gc>>(
 }
 
 pub(crate) fn get_num(val: StrictValue<'_>) -> Option<NixNum> {
-    if let Some(i) = val.as_inline::<i32>() {
+    if let Some(i) = val.downcast::<i32>() {
         Some(NixNum::Int(i64::from(i)))
-    } else if let Some(gc_i) = val.as_gc::<i64>() {
+    } 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)
     }
 }
 
@@ -304,13 +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::Float(a)), Some(NixNum::Float(b))) => Ok(Value::new(float_op(a, b))),
-        (Some(NixNum::Int(a)), Some(NixNum::Float(b))) => {
+        (Some(NixNum::Int(a)), Some(NixNum::Float(b))) => Ok(Value::new(float_op(a as f64, b))),
-            Ok(Value::new_float(float_op(a as f64, b)))
+        (Some(NixNum::Float(a)), Some(NixNum::Int(b))) => Ok(Value::new(float_op(a, b as f64))),
-        }
-        (Some(NixNum::Float(a)), Some(NixNum::Int(b))) => {
-            Ok(Value::new_float(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

@@ -21,7 +21,7 @@ pub(crate) fn call<'gc, M: Machine<'gc>>(
         return m.finish_err(Error::eval_error("stack overflow; max-call-depth exceeded"));
     }
     m.inc_call_depth();
-    if let Some(closure) = func.as_gc::<Closure>() {
+    if let Some(closure) = func.downcast::<Closure>() {
         if closure.pattern.is_some() {
             // FIXME: better DX...
             m.push(func.relax());
@@ -46,7 +46,7 @@ pub(crate) fn call<'gc, M: Machine<'gc>>(
         });
         reader.set_pc(ip as usize);
         m.set_env(new_env);
-    } else if let Some(primop) = func.as_inline::<PrimOp>() {
+    } else if let Some(primop) = func.downcast::<PrimOp>() {
         if primop.arity == 1 {
             m.push(arg);
             m.push_call_frame(CallFrame {
@@ -61,9 +61,9 @@ pub(crate) fn call<'gc, M: Machine<'gc>>(
                 arity: primop.arity - 1,
                 args: [arg, Value::default(), Value::default()],
             };
-            m.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 {
                 m.push(app.args[i as usize]);
@@ -82,9 +82,9 @@ pub(crate) fn call<'gc, M: Machine<'gc>>(
                 ..*app
             };
             new_app.args[position] = arg;
-            m.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>()
+    } else if let Some(attrs) = func.downcast::<AttrSet>()
         && let Some(functor) = attrs.lookup(m.functor_sym())
     {
         // f arg  =>  (f.__functor f) arg

fix-vm/src/instructions/closures.rs

@@ -17,7 +17,7 @@ pub(crate) fn op_make_thunk<'gc, M: Machine<'gc>>(
             env: m.env(),
         }),
     );
-    m.push(Value::new_gc(thunk));
+    m.push(Value::new(thunk));
     Step::Continue(())
 }
 
@@ -38,7 +38,7 @@ pub(crate) fn op_make_closure<'gc, M: Machine<'gc>>(
             pattern: None,
         },
     );
-    m.push(Value::new_gc(closure));
+    m.push(Value::new(closure));
     Step::Continue(())
 }
 
@@ -88,6 +88,6 @@ pub(crate) fn op_make_pattern_closure<'gc, M: Machine<'gc>>(
             pattern: Some(pattern),
         },
     );
-    m.push(Value::new_gc(closure));
+    m.push(Value::new(closure));
     Step::Continue(())
 }

fix-vm/src/instructions/collections.rs

@@ -57,7 +57,7 @@ pub(crate) fn op_make_attrs<'gc, M: Machine<'gc>>(
 
     kv.sort_by_key(|(k, _)| *k);
     let attrs = Gc::new(mc, AttrSet::from_sorted_unchecked(kv));
-    m.push(Value::new_gc(attrs));
+    m.push(Value::new(attrs));
     Step::Continue(())
 }
 
@@ -195,7 +195,7 @@ pub(crate) fn op_has_attr_path_static<'gc, M: Machine<'gc>>(
     let current = m.force_and_retry::<StrictValue>(reader, mc)?;
 
     match current
-        .as_gc::<AttrSet>()
+        .downcast::<AttrSet>()
         .and_then(|attrs| attrs.lookup(key))
     {
         Some(v) => {
@@ -223,7 +223,7 @@ pub(crate) fn op_has_attr_path_dynamic<'gc, M: Machine<'gc>>(
     };
 
     match current
-        .as_gc::<AttrSet>()
+        .downcast::<AttrSet>()
         .and_then(|attrs| attrs.lookup(key_sid))
     {
         Some(v) => {
@@ -263,9 +263,9 @@ pub(crate) fn op_has_attr_static<'gc, M: Machine<'gc>>(
     let key = reader.read_string_id();
     let current = m.force_and_retry::<StrictValue>(reader, mc)?;
 
-    m.push(Value::new_inline(
+    m.push(Value::new(
         current
-            .as_gc::<AttrSet>()
+            .downcast::<AttrSet>()
             .and_then(|attrs| attrs.lookup(key))
             .is_some(),
     ));
@@ -289,9 +289,9 @@ pub(crate) fn op_has_attr_dynamic<'gc, M: MachineExt<'gc>>(
         Err(got) => return m.finish_type_err(NixType::String, got),
     };
 
-    m.push(Value::new_inline(
+    m.push(Value::new(
         current
-            .as_gc::<AttrSet>()
+            .downcast::<AttrSet>()
             .and_then(|attrs| attrs.lookup(key_sid))
             .is_some(),
     ));
@@ -304,7 +304,7 @@ pub(crate) fn op_has_attr_dynamic<'gc, M: MachineExt<'gc>>(
 #[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)
-    m.push(Value::new_inline(false));
+    m.push(Value::new(false));
     Step::Continue(())
 }
 
@@ -326,7 +326,7 @@ pub(crate) fn op_make_list<'gc, M: Machine<'gc>>(
             inner: RefLock::new(items),
         },
     );
-    m.push(Value::new_gc(list));
+    m.push(Value::new(list));
     Step::Continue(())
 }
 

fix-vm/src/instructions/control.rs

@@ -12,7 +12,7 @@ pub(crate) fn op_jump_if_false<'gc, M: Machine<'gc>>(
 ) -> Step {
     let offset = reader.read_i32();
     let cond = m.force_and_retry::<StrictValue>(reader, mc)?;
-    if cond.as_inline::<bool>() == Some(false) {
+    if cond.downcast::<bool>() == Some(false) {
         reader.set_pc(((reader.pc() as isize) + (offset as isize)) as usize);
     }
     Step::Continue(())
@@ -26,7 +26,7 @@ pub(crate) fn op_jump_if_true<'gc, M: Machine<'gc>>(
 ) -> Step {
     let offset = reader.read_i32();
     let cond = m.force_and_retry::<StrictValue>(reader, mc)?;
-    if cond.as_inline::<bool>() == Some(true) {
+    if cond.downcast::<bool>() == Some(true) {
         reader.set_pc(((reader.pc() as isize) + (offset as isize)) as usize);
     }
     Step::Continue(())

fix-vm/src/instructions/literals.rs

@@ -9,7 +9,7 @@ pub(crate) fn op_push_smi<'gc, M: Machine<'gc>>(
     reader: &mut BytecodeReader<'_>,
 ) -> Step {
     let val = reader.read_i32();
-    m.push(Value::new_inline(val));
+    m.push(Value::new(val));
     Step::Continue(())
 }
 
@@ -20,7 +20,7 @@ pub(crate) fn op_push_bigint<'gc, M: Machine<'gc>>(
     mc: &Mutation<'gc>,
 ) -> Step {
     let val = reader.read_i64();
-    m.push(Value::new_gc(Gc::new(mc, val)));
+    m.push(Value::new(Gc::new(mc, val)));
     Step::Continue(())
 }
 
@@ -30,7 +30,7 @@ pub(crate) fn op_push_float<'gc, M: Machine<'gc>>(
     reader: &mut BytecodeReader<'_>,
 ) -> Step {
     let val = reader.read_f64();
-    m.push(Value::new_float(val));
+    m.push(Value::new(val));
     Step::Continue(())
 }
 
@@ -40,24 +40,24 @@ pub(crate) fn op_push_string<'gc, M: Machine<'gc>>(
     reader: &mut BytecodeReader<'_>,
 ) -> Step {
     let sid = reader.read_string_id();
-    m.push(Value::new_inline(sid));
+    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_inline(crate::Null));
+    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_inline(true));
+    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_inline(false));
+    m.push(Value::new(false));
     Step::Continue(())
 }

fix-vm/src/instructions/misc.rs

@@ -22,7 +22,7 @@ pub(crate) fn op_load_builtin<'gc, M: Machine<'gc>>(
 ) -> Step {
     let Ok(id) = BuiltinId::try_from(reader.read_u8())
         .map_err(|err| panic!("unknown builtin id: {}", err.number));
-    m.push(Value::new_inline(PrimOp {
+    m.push(Value::new(PrimOp {
         id,
         arity: BUILTINS[id as usize].1,
         dispatch_ip: Continuation::entry_for_builtin(id).ip(),
@@ -49,7 +49,7 @@ pub(crate) fn op_load_scoped_binding<'gc, M: Machine<'gc>>(
     let slot_id = reader.read_u32();
     let name = reader.read_string_id();
     let scope = m.scope_slot(slot_id);
-    let Some(attrs) = scope.as_gc::<AttrSet>() else {
+    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) {
@@ -73,10 +73,10 @@ pub(crate) fn op_coerce_to_string<'gc, M: Machine<'gc>>(
     let val = m.force_and_retry::<StrictValue>(reader, mc)?;
     if val.is::<StringId>() || val.is::<NixString>() {
         m.push(val.relax());
-    } else if let Some(p) = val.as_inline::<Path>() {
+    } else if let Some(p) = val.downcast::<Path>() {
         // Coercing a path to a string yields the canonical path text.
         // FIXME: copy to store
-        m.push(Value::new_inline(p.0));
+        m.push(Value::new(p.0));
     } else {
         todo!("coerce other types to string: {:?}", val.ty());
     }
@@ -122,10 +122,10 @@ pub(crate) fn op_concat_strings<'gc, M: Machine<'gc>>(
 
     if merged.is_empty() {
         let sid = ctx.intern_string(result);
-        m.push(Value::new_inline(sid));
+        m.push(Value::new(sid));
     } else {
         let ns = gc_arena::Gc::new(mc, NixString::with_context(result, merged));
-        m.push(Value::new_gc(ns));
+        m.push(Value::new(ns));
     }
     Step::Continue(())
 }
@@ -140,8 +140,8 @@ pub(crate) fn op_resolve_path<'gc, M: MachineExt<'gc>>(
     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>() {
+    if let Some(p) = path_val.downcast::<Path>() {
-        m.push(Value::new_inline(p));
+        m.push(Value::new(p));
         return Step::Continue(());
     }
     let path = match ctx.get_string(path_val) {
@@ -158,7 +158,7 @@ pub(crate) fn op_resolve_path<'gc, M: MachineExt<'gc>>(
         Err(e) => return m.finish_err(e),
     };
     let sid = ctx.intern_string(resolved);
-    m.push(Value::new_inline(Path(sid)));
+    m.push(Value::new(Path(sid)));
     Step::Continue(())
 }
 

fix-vm/src/instructions/with_scope.rs

@@ -13,7 +13,7 @@ pub(crate) fn op_lookup_with<'gc, M: Machine<'gc>>(
     mc: &gc_arena::Mutation<'gc>,
 ) -> Step {
     #[allow(clippy::unwrap_used)]
-    let counter = m.peek_forced(0).as_inline::<i32>().unwrap();
+    let counter = m.peek_forced(0).downcast::<i32>().unwrap();
 
     let name = reader.read_string_id();
     let n = reader.read_u8();
@@ -57,7 +57,7 @@ pub(crate) fn op_lookup_with<'gc, M: Machine<'gc>>(
     };
 
     if let Some(val) = namespace
-        .as_gc::<AttrSet>()
+        .downcast::<AttrSet>()
         .and_then(|attrs| attrs.lookup(name))
     {
         m.replace(0, val);
@@ -67,7 +67,7 @@ pub(crate) fn op_lookup_with<'gc, M: Machine<'gc>>(
             Symbol::from(ctx.resolve_string(name))
         )));
     } else {
-        m.replace(0, Value::new_inline(counter + 1));
+        m.replace(0, Value::new(counter + 1));
         reader.set_pc(resume_pc);
     }
 

fix-vm/src/lib.rs

@@ -7,7 +7,7 @@
 
 use std::path::PathBuf;
 
-use fix_bytecode::{InstructionPtr, Continuation};
+use fix_bytecode::{Continuation, InstructionPtr};
 use fix_error::{Error, Result, Source};
 use fix_lang::{BUILTINS, BuiltinId, StringId};
 use gc_arena::metrics::Pacing;
@@ -63,7 +63,7 @@ fn init_builtins<'gc>(mc: &Mutation<'gc>, ctx: &mut impl VmRuntimeCtx) -> Value<
         let dispatch_ip = Continuation::entry_for_builtin(id).ip();
         entries.push((
             name,
-            Value::new_inline(PrimOp {
+            Value::new(PrimOp {
                 id,
                 arity,
                 dispatch_ip,
@@ -74,21 +74,15 @@ 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)),
+        ("__langVersion", Value::new(6i32)),
-        (
+        ("__nixVersion", Value::new(ctx.intern_string("2.24.0"))),
-            "__nixVersion",
+        ("__storeDir", Value::new(ctx.intern_string("/nix/store"))),
-            Value::new_inline(ctx.intern_string("2.24.0")),
+        ("__nixPath", Value::new(Gc::new(mc, List::default()))),
-        ),
+        ("null", Value::new(Null)),
-        (
+        ("true", Value::new(true)),
-            "__storeDir",
+        ("false", Value::new(false)),
-            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)),
     ];
 
     for (name, val) in consts {
@@ -99,12 +93,12 @@ 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
@@ -125,8 +119,8 @@ impl<'gc> Vm<'gc> {
             scope_slots: Vec::new(),
 
             builtins,
-            empty_list: Value::new_gc(Gc::new(mc, List::default())),
+            empty_list: Value::new(Gc::new(mc, List::default())),
-            empty_attrs: Value::new_gc(Gc::new(mc, AttrSet::default())),
+            empty_attrs: Value::new(Gc::new(mc, AttrSet::default())),
 
             force_mode,
 
@@ -202,7 +196,7 @@ impl<'gc> Machine<'gc> for Vm<'gc> {
         mc: &Mutation<'gc>,
         resume_pc: usize,
     ) -> Step {
-        let Some(thunk) = self.peek(depth).as_gc::<Thunk>() else {
+        let Some(thunk) = self.peek(depth).downcast::<Thunk>() else {
             return Step::Continue(());
         };
         let mut state = thunk.borrow_mut(mc);

fix-vm/src/primops/context.rs

@@ -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>() {
+    if let Some(sid) = val.downcast::<StringId>() {
-        return m.return_from_primop(Value::new_inline(sid), reader);
+        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>() {
+    if let Some(sid) = val.downcast::<StringId>() {
-        return m.return_from_primop(Value::new_inline(sid), reader);
+        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
@@ -192,9 +192,9 @@ 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(attrs));
-    m.push(Value::new_inline(0i32));
+    m.push(Value::new(0i32));
-    m.push(Value::new_gc(acc));
+    m.push(Value::new(acc));
 
     reader.set_pc(Continuation::PAppendContextLoop.ip() as usize);
     Step::Continue(())
@@ -207,9 +207,9 @@ pub fn append_context_loop<'gc, M: Machine<'gc>>(
     mc: &Mutation<'gc>,
 ) -> Step {
     #[allow(clippy::unwrap_used)]
-    let idx = m.peek(1).as_inline::<i32>().unwrap();
+    let idx = m.peek(1).downcast::<i32>().unwrap();
     #[allow(clippy::unwrap_used)]
-    let attrs = m.peek_forced(2).as_gc::<AttrSet>().unwrap();
+    let attrs = m.peek_forced(2).downcast::<AttrSet>().unwrap();
 
     if idx as usize >= attrs.entries.len() {
         return append_context_finalize(m, ctx, reader, mc);
@@ -238,14 +238,14 @@ 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();
+    let idx = m.peek(2).downcast::<i32>().unwrap();
     #[allow(clippy::unwrap_used)]
-    let outer = m.peek_forced(3).as_gc::<AttrSet>().unwrap();
+    let outer = m.peek_forced(3).downcast::<AttrSet>().unwrap();
     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/") {
@@ -263,11 +263,11 @@ pub fn append_context_entry_forced<'gc, M: Machine<'gc>>(
     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>().unwrap();
     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 +275,7 @@ 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 +288,7 @@ 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);
@@ -304,8 +304,8 @@ pub fn append_context_entry_forced<'gc, M: Machine<'gc>>(
 
     let _ = m.pop();
     #[allow(clippy::unwrap_used)]
-    let idx_back = m.peek(1).as_inline::<i32>().unwrap();
+    let idx_back = m.peek(1).downcast::<i32>().unwrap();
-    m.replace(1, Value::new_inline(idx_back + 1));
+    m.replace(1, Value::new(idx_back + 1));
     reader.set_pc(Continuation::PAppendContextLoop.ip() as usize);
     Step::Continue(())
 }
@@ -318,20 +318,20 @@ 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();
+        let idx_back = m.peek(1).downcast::<i32>().unwrap();
-        m.replace(1, Value::new_inline(idx_back + 1));
+        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));
+    m.push(Value::new(0i32));
     reader.set_pc(Continuation::PAppendContextOutputElementLoop.ip() as usize);
     Step::Continue(())
 }
@@ -343,9 +343,9 @@ pub fn append_context_output_element_loop<'gc, M: Machine<'gc>>(
     mc: &Mutation<'gc>,
 ) -> Step {
     #[allow(clippy::unwrap_used)]
-    let oidx = m.peek(0).as_inline::<i32>().unwrap();
+    let oidx = m.peek(0).downcast::<i32>().unwrap();
     #[allow(clippy::unwrap_used)]
-    let list = m.peek_forced(1).as_gc::<VmList>().unwrap();
+    let list = m.peek_forced(1).downcast::<VmList>().unwrap();
     let len = list.inner.borrow().len();
     if oidx as usize >= len {
         // Stack: [strVal, attrs, idx, acc, list, oidx] -> drop oidx & list,
@@ -353,8 +353,8 @@ pub fn append_context_output_element_loop<'gc, M: Machine<'gc>>(
         let _ = m.pop();
         let _ = m.pop();
         #[allow(clippy::unwrap_used)]
-        let idx_back = m.peek(1).as_inline::<i32>().unwrap();
+        let idx_back = m.peek(1).downcast::<i32>().unwrap();
-        m.replace(1, Value::new_inline(idx_back + 1));
+        m.replace(1, Value::new(idx_back + 1));
         reader.set_pc(Continuation::PAppendContextLoop.ip() as usize);
         return Step::Continue(());
     }
@@ -385,9 +385,9 @@ 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();
+    let idx = m.peek(4).downcast::<i32>().unwrap();
     #[allow(clippy::unwrap_used)]
-    let outer = m.peek_forced(5).as_gc::<AttrSet>().unwrap();
+    let outer = m.peek_forced(5).downcast::<AttrSet>().unwrap();
     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") {
@@ -397,21 +397,21 @@ 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>().unwrap();
     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();
+    let oidx = m.peek(0).downcast::<i32>().unwrap();
-    m.replace(0, Value::new_inline(oidx + 1));
+    m.replace(0, Value::new(oidx + 1));
     reader.set_pc(Continuation::PAppendContextOutputElementLoop.ip() as usize);
     Step::Continue(())
 }
@@ -424,7 +424,7 @@ fn append_context_finalize<'gc, M: Machine<'gc>>(
 ) -> Step {
     // Stack: [strVal, attrs, idx, acc]
     #[allow(clippy::unwrap_used)]
-    let acc_gc = m.pop().as_gc::<NixString>().unwrap();
+    let acc_gc = m.pop().downcast::<NixString>().unwrap();
     let _ = m.pop(); // idx
     let _ = m.pop(); // attrs
     let str_val_raw = m.pop();
@@ -438,10 +438,10 @@ 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

@@ -44,14 +44,14 @@ pub fn deep_seq_force_top<'gc, M: Machine<'gc>>(
 
     let e1 = m.peek_forced(1);
 
-    let children: SmallVec<_> = if let Some(attrs) = e1.as_gc::<AttrSet>() {
+    let children: SmallVec<_> = if let Some(attrs) = e1.downcast::<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>>() {
+    } else if let Some(list) = e1.downcast::<List>() {
         let inner = list.inner.borrow();
         if inner.is_empty() {
             SmallVec::new()
@@ -69,15 +69,15 @@ pub fn deep_seq_force_top<'gc, M: Machine<'gc>>(
     }
 
     let count = children.len() as i32;
-    let seen: Gc<'gc, List<'gc>> = Gc::new(mc, List::default());
+    let seen = Gc::new(mc, List::default());
-    let worklist: Gc<'gc, List<'gc>> = List::new(mc, children);
+    let worklist = List::new(mc, children);
 
     let e2 = m.pop();
     let _ = m.pop();
     m.push(e2);
-    m.push(Value::new_gc(seen));
+    m.push(Value::new(seen));
-    m.push(Value::new_gc(worklist));
+    m.push(Value::new(worklist));
-    m.push(Value::new_inline(count));
+    m.push(Value::new(count));
     reader.set_pc(Continuation::PDeepSeqPush.ip() as usize);
     Step::Continue(())
 }
@@ -89,7 +89,7 @@ pub fn deep_seq_push<'gc, M: Machine<'gc>>(
 ) -> Step {
     // stack: [e2, seen, worklist, counter]
     #[allow(clippy::unwrap_used)]
-    let counter = m.peek(0).as_inline::<i32>().unwrap();
+    let counter = m.peek(0).downcast::<i32>().unwrap();
     if counter == 0 {
         let _ = m.pop(); // counter
         let _ = m.pop(); // worklist
@@ -99,10 +99,10 @@ pub fn deep_seq_push<'gc, M: Machine<'gc>>(
     }
 
     #[allow(clippy::unwrap_used)]
-    let worklist = m.peek_forced(1).as_gc::<List<'gc>>().unwrap();
+    let worklist = m.peek_forced(1).downcast::<List>().unwrap();
     #[allow(clippy::unwrap_used)]
     let item = worklist.unlock(mc).borrow_mut().pop().unwrap();
-    m.replace(0, Value::new_inline(counter - 1));
+    m.replace(0, Value::new(counter - 1));
     m.push(item);
 
     // force item at TOS, resume at DeepSeqLoop after force
@@ -119,17 +119,17 @@ pub fn deep_seq_loop<'gc, M: Machine<'gc>>(
     // 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 counter = m.peek(0).downcast::<i32>().unwrap();
 
     let mut added: usize = 0;
-    if let Some(attrs) = item.as_gc::<AttrSet>() {
+    if let Some(attrs) = item.downcast::<AttrSet>() {
         let attrs = &attrs.entries;
         #[allow(clippy::unwrap_used)]
-        let seen = m.peek_forced(2).as_gc::<List<'gc>>().unwrap();
+        let seen = m.peek_forced(2).downcast::<List>().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 worklist = m.peek_forced(1).downcast::<List>().unwrap();
             {
                 let mut wl = worklist.unlock(mc).borrow_mut();
                 for &(_, v) in attrs.iter() {
@@ -138,13 +138,13 @@ pub fn deep_seq_loop<'gc, M: Machine<'gc>>(
                 added = attrs.len();
             }
         }
-    } else if let Some(list) = item.as_gc::<List<'gc>>() {
+    } else if let Some(list) = item.downcast::<List>() {
         #[allow(clippy::unwrap_used)]
-        let seen = m.peek_forced(2).as_gc::<List<'gc>>().unwrap();
+        let seen = m.peek_forced(2).downcast::<List>().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 worklist = m.peek_forced(1).downcast::<List>().unwrap();
             {
                 let inner = list.inner.borrow();
                 let mut wl = worklist.unlock(mc).borrow_mut();
@@ -156,7 +156,7 @@ pub fn deep_seq_loop<'gc, M: Machine<'gc>>(
         }
     }
 
-    m.replace(0, Value::new_inline(counter + added as i32));
+    m.replace(0, Value::new(counter + added as i32));
     reader.set_pc(Continuation::PDeepSeqPush.ip() as usize);
     Step::Continue(())
 }
@@ -170,10 +170,10 @@ 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 {
@@ -185,8 +185,8 @@ 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(0i32));
-    m.push(Value::new_inline(count as i32));
+    m.push(Value::new(count as i32));
     reader.set_pc(Continuation::ForceResultShallowPush.ip() as usize);
     Step::Continue(())
 }
@@ -198,9 +198,9 @@ pub fn force_result_shallow_push<'gc, M: Machine<'gc>>(
     mc: &Mutation<'gc>,
 ) -> Step {
     #[allow(clippy::unwrap_used)]
-    let idx = m.peek(1).as_inline::<i32>().unwrap();
+    let idx = m.peek(1).downcast::<i32>().unwrap();
     #[allow(clippy::unwrap_used)]
-    let len = m.peek(0).as_inline::<i32>().unwrap();
+    let len = m.peek(0).downcast::<i32>().unwrap();
 
     if idx == len {
         let _ = m.pop(); // len
@@ -210,16 +210,16 @@ pub fn force_result_shallow_push<'gc, M: Machine<'gc>>(
     }
 
     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,
@@ -349,7 +349,7 @@ 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

@@ -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>() {
+    if let Some(p) = val.downcast::<Path>() {
-        return m.return_from_primop(Value::new_inline(p.0), reader);
+        return m.return_from_primop(Value::new(p.0), reader);
     }
     //  TODO: derivations / `__toString` / `outPath`,
     //        numbers, lists.
@@ -47,5 +47,5 @@ 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

@@ -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) => {
@@ -44,15 +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() {
@@ -92,13 +92,13 @@ fn finalize<'gc, M: Machine<'gc>>(m: &mut M, reader: &mut BytecodeReader<'_>) ->
     let _ = m.pop();
     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>>(
@@ -111,7 +111,7 @@ 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(
@@ -140,11 +140,11 @@ 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();
@@ -169,10 +169,10 @@ fn enter_eq_machine<'gc, M: Machine<'gc>>(
         env: m.env(),
     });
     m.inc_call_depth();
-    m.push(Value::new_inline(negate));
+    m.push(Value::new(negate));
-    m.push(Value::new_inline(true));
+    m.push(Value::new(true));
-    m.push(Value::new_gc(List::new(mc, lhs_init)));
+    m.push(Value::new(List::new(mc, lhs_init)));
-    m.push(Value::new_gc(List::new(mc, rhs_init)));
+    m.push(Value::new(List::new(mc, rhs_init)));
     reader.set_pc(Continuation::EqStep.ip() as usize);
     Step::Continue(())
 }
@@ -189,7 +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,
@@ -198,25 +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() {

fix-vm/src/primops/io.rs

@@ -40,7 +40,7 @@ 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: Continuation::PImportFinalize.ip() as usize,
@@ -63,7 +63,7 @@ pub fn import_finalize<'gc, M: Machine<'gc>>(
     // 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>().unwrap();
     // 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();
@@ -107,7 +107,7 @@ 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 {
@@ -146,7 +146,7 @@ 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 +171,7 @@ 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

@@ -8,7 +8,7 @@ pub fn filter_force_list<'gc, M: Machine<'gc>>(
     mc: &Mutation<'gc>,
 ) -> Step {
     m.force_slot(0, reader, mc)?;
-    let list = match m.peek_forced(0).expect_gc::<List>() {
+    let list = match m.peek_forced(0).expect::<List>() {
         Ok(list) => list,
         Err(got) => return m.finish_type_err(NixType::List, got),
     };
@@ -18,8 +18,8 @@ pub fn filter_force_list<'gc, M: Machine<'gc>>(
         return m.return_from_primop(val, reader);
     }
     // prepare stack layout: [ pred list idx acc ]
-    m.push(Value::new_inline(0));
+    m.push(Value::new(0));
-    m.push(Value::new_gc(List::new_gc(mc)));
+    m.push(Value::new(List::new_gc(mc)));
     reader.set_pc(Continuation::PFilterCallPred.ip() as usize);
     Step::Continue(())
 }
@@ -32,9 +32,9 @@ pub fn filter_call_pred<'gc, M: Machine<'gc>>(
     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();
+    let idx = m.peek(1).downcast::<i32>().unwrap();
     #[allow(clippy::unwrap_used)]
-    let elem = m.peek_forced(2).as_gc::<List>().unwrap().inner.borrow()[idx as usize];
+    let elem = m.peek_forced(2).downcast::<List>().unwrap().inner.borrow()[idx as usize];
     m.push(pred.relax());
     m.call(reader, mc, elem, Continuation::PFilterCheck.ip() as usize)
 }
@@ -46,12 +46,12 @@ pub fn filter_check<'gc, M: Machine<'gc>>(
 ) -> Step {
     let ret = m.force_and_retry::<bool>(reader, mc)?;
     #[allow(clippy::unwrap_used)]
-    let idx = m.peek(1).as_inline::<i32>().unwrap();
+    let idx = m.peek(1).downcast::<i32>().unwrap();
     #[allow(clippy::unwrap_used)]
-    let list = m.peek_forced(2).as_gc::<List>().unwrap();
+    let list = m.peek_forced(2).downcast::<List>().unwrap();
     let list = list.inner.borrow();
     #[allow(clippy::unwrap_used)]
-    let acc = m.peek_forced(0).as_gc::<List>().unwrap();
+    let acc = m.peek_forced(0).downcast::<List>().unwrap();
     if ret {
         let mut acc = acc.unlock(mc).borrow_mut();
         acc.push(list[idx as usize]);
@@ -63,7 +63,7 @@ pub fn filter_check<'gc, M: Machine<'gc>>(
         let _ = m.pop(); // pred
         return m.return_from_primop(acc, reader);
     }
-    m.replace(1, Value::new_inline(idx + 1));
+    m.replace(1, Value::new(idx + 1));
     reader.set_pc(Continuation::PFilterCallPred.ip() as usize);
     Step::Continue(())
 }
@@ -83,7 +83,7 @@ pub fn foldl_strict_entry<'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::<List>() else {
+    let Some(list) = list_val.downcast::<List>() else {
         return m.finish_type_err(NixType::List, list_val.ty());
     };
     if list.inner.borrow().is_empty() {
@@ -94,7 +94,7 @@ pub fn foldl_strict_entry<'gc, M: Machine<'gc>>(
     let list_val = m.pop();
     let nul_val = m.pop();
     m.push(list_val);
-    m.push(Value::new_inline(0i32));
+    m.push(Value::new(0i32));
     m.push(nul_val);
     reader.set_pc(Continuation::PFoldlStrictCall1.ip() as usize);
     Step::Continue(())
@@ -119,7 +119,12 @@ pub fn foldl_strict_call1<'gc, M: Machine<'gc>>(
     let op = m.peek_forced(3);
     let acc = m.peek(0);
     m.push(op.relax());
-    m.call(reader, mc, acc, Continuation::PFoldlStrictCall2.ip() as usize)
+    m.call(
+        reader,
+        mc,
+        acc,
+        Continuation::PFoldlStrictCall2.ip() as usize,
+    )
 }
 
 pub fn foldl_strict_call2<'gc, M: Machine<'gc>>(
@@ -128,9 +133,9 @@ pub fn foldl_strict_call2<'gc, M: Machine<'gc>>(
     mc: &Mutation<'gc>,
 ) -> Step {
     #[allow(clippy::unwrap_used)]
-    let idx = m.peek(2).as_inline::<i32>().unwrap();
+    let idx = m.peek(2).downcast::<i32>().unwrap();
     #[allow(clippy::unwrap_used)]
-    let list = m.peek_forced(3).as_gc::<List>().unwrap();
+    let list = m.peek_forced(3).downcast::<List>().unwrap();
     let elem = list.inner.borrow()[idx as usize];
     m.call(
         reader,
@@ -148,9 +153,9 @@ pub fn foldl_strict_update<'gc, M: Machine<'gc>>(
     let result = m.pop();
     m.replace(0, result);
     #[allow(clippy::unwrap_used)]
-    let idx = m.peek(1).as_inline::<i32>().unwrap();
+    let idx = m.peek(1).downcast::<i32>().unwrap();
     #[allow(clippy::unwrap_used)]
-    let list = m.peek_forced(2).as_gc::<List>().unwrap();
+    let list = m.peek_forced(2).downcast::<List>().unwrap();
     let len = list.inner.borrow().len();
     if (idx as usize) + 1 == len {
         let acc = m.pop();
@@ -159,7 +164,7 @@ pub fn foldl_strict_update<'gc, M: Machine<'gc>>(
         let _ = m.pop(); // op
         return m.return_from_primop(acc, reader);
     }
-    m.replace(1, Value::new_inline(idx + 1));
+    m.replace(1, Value::new(idx + 1));
     reader.set_pc(Continuation::PFoldlStrictCall1.ip() as usize);
     Step::Continue(())
 }
@@ -170,7 +175,7 @@ pub fn all_entry<'gc, M: Machine<'gc>>(
     mc: &Mutation<'gc>,
 ) -> Step {
     m.force_slot(0, reader, mc)?;
-    let list = match m.peek_forced(0).expect_gc::<List>() {
+    let list = match m.peek_forced(0).expect::<List>() {
         Ok(list) => list,
         Err(got) => return m.finish_type_err(NixType::List, got),
     };
@@ -179,10 +184,10 @@ pub fn all_entry<'gc, M: Machine<'gc>>(
     if list.inner.borrow().is_empty() {
         let _list = m.pop();
         let _pred = m.pop();
-        return m.return_from_primop(Value::new_inline(true), reader);
+        return m.return_from_primop(Value::new(true), reader);
     }
     // prepare stack layout: [ pred list idx ]
-    m.push(Value::new_inline(0));
+    m.push(Value::new(0));
     reader.set_pc(Continuation::PAllCallPred.ip() as usize);
     Step::Continue(())
 }
@@ -194,9 +199,9 @@ pub fn all_call_pred<'gc, M: Machine<'gc>>(
 ) -> Step {
     let pred = m.peek_forced(2);
     #[allow(clippy::unwrap_used)]
-    let idx = m.peek(0).as_inline::<i32>().unwrap();
+    let idx = m.peek(0).downcast::<i32>().unwrap();
     #[allow(clippy::unwrap_used)]
-    let elem = m.peek_forced(1).as_gc::<List>().unwrap().inner.borrow()[idx as usize];
+    let elem = m.peek_forced(1).downcast::<List>().unwrap().inner.borrow()[idx as usize];
     m.push(pred.relax());
     m.call(reader, mc, elem, Continuation::PAllCheck.ip() as usize)
 }
@@ -208,17 +213,17 @@ pub fn all_check<'gc, M: Machine<'gc>>(
 ) -> Step {
     let ret = m.force_and_retry::<bool>(reader, mc)?;
     #[allow(clippy::unwrap_used)]
-    let idx = m.peek(0).as_inline::<i32>().unwrap();
+    let idx = m.peek(0).downcast::<i32>().unwrap();
     #[allow(clippy::unwrap_used)]
-    let list = m.peek_forced(1).as_gc::<List>().unwrap();
+    let list = m.peek_forced(1).downcast::<List>().unwrap();
     let list = list.inner.borrow();
     if idx as usize == list.len() - 1 || !ret {
         let _ = m.pop(); // idx
         let _ = m.pop(); // list
         let _ = m.pop(); // pred
-        return m.return_from_primop(Value::new_inline(ret), reader);
+        return m.return_from_primop(Value::new(ret), reader);
     }
-    m.replace(0, Value::new_inline(idx + 1));
+    m.replace(0, Value::new(idx + 1));
     reader.set_pc(Continuation::PAllCallPred.ip() as usize);
     Step::Continue(())
 }
@@ -229,7 +234,7 @@ pub fn any_entry<'gc, M: Machine<'gc>>(
     mc: &Mutation<'gc>,
 ) -> Step {
     m.force_slot(0, reader, mc)?;
-    let list = match m.peek_forced(0).expect_gc::<List>() {
+    let list = match m.peek_forced(0).expect::<List>() {
         Ok(list) => list,
         Err(got) => return m.finish_type_err(NixType::List, got),
     };
@@ -238,10 +243,10 @@ pub fn any_entry<'gc, M: Machine<'gc>>(
     if list.inner.borrow().is_empty() {
         let _list = m.pop();
         let _pred = m.pop();
-        return m.return_from_primop(Value::new_inline(false), reader);
+        return m.return_from_primop(Value::new(false), reader);
     }
     // prepare stack layout: [ pred list idx ]
-    m.push(Value::new_inline(0));
+    m.push(Value::new(0));
     reader.set_pc(Continuation::PAnyCallPred.ip() as usize);
     Step::Continue(())
 }
@@ -253,9 +258,9 @@ pub fn any_call_pred<'gc, M: Machine<'gc>>(
 ) -> Step {
     let pred = m.peek_forced(2);
     #[allow(clippy::unwrap_used)]
-    let idx = m.peek(0).as_inline::<i32>().unwrap();
+    let idx = m.peek(0).downcast::<i32>().unwrap();
     #[allow(clippy::unwrap_used)]
-    let elem = m.peek_forced(1).as_gc::<List>().unwrap().inner.borrow()[idx as usize];
+    let elem = m.peek_forced(1).downcast::<List>().unwrap().inner.borrow()[idx as usize];
     m.push(pred.relax());
     m.call(reader, mc, elem, Continuation::PAnyCheck.ip() as usize)
 }
@@ -267,17 +272,17 @@ pub fn any_check<'gc, M: Machine<'gc>>(
 ) -> Step {
     let ret = m.force_and_retry::<bool>(reader, mc)?;
     #[allow(clippy::unwrap_used)]
-    let idx = m.peek(0).as_inline::<i32>().unwrap();
+    let idx = m.peek(0).downcast::<i32>().unwrap();
     #[allow(clippy::unwrap_used)]
-    let list = m.peek_forced(1).as_gc::<List>().unwrap();
+    let list = m.peek_forced(1).downcast::<List>().unwrap();
     let list = list.inner.borrow();
     if idx as usize == list.len() - 1 || ret {
         let _ = m.pop(); // idx
         let _ = m.pop(); // list
         let _ = m.pop(); // pred
-        return m.return_from_primop(Value::new_inline(ret), reader);
+        return m.return_from_primop(Value::new(ret), reader);
     }
-    m.replace(0, Value::new_inline(idx + 1));
+    m.replace(0, Value::new(idx + 1));
     reader.set_pc(Continuation::PAnyCallPred.ip() as usize);
     Step::Continue(())
 }

fix-vm/src/primops/path.rs

@@ -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>() {
+    if let Some(Path(s)) = val.downcast::<Path>() {
-        return m.return_from_primop(Value::new_inline(s), reader);
+        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)
 }