diff --git a/TODO.md b/TODO.md
index 234d694..dfcbefd 100644
--- a/TODO.md
+++ b/TODO.md
@@ -11,17 +11,145 @@
 阻拦变量解析的是 `with import` 而不是一般的 `with`
 解析阶段可以解决除涉及非字符串常量拼接路径导入之外的问题
 
-# 工作流程
+静态分析图与求值期图分离，动态生成求值期图
+
+依赖类型：
+1. 强依赖 (x!)
+  - builtins.toString x => x!
+  - x + y => x! y!
+  - { x = 1; ${sym} = 2; } => sym!
+2. 弱依赖 a.k.a. thunk (x?)
+  - builtins.seq x y => x! y?
+3. 递归依赖 (x!!)
+  - builtins.deepSeq x y => x!! y?
+
+e.g.
+- let a? = { inherit a?; }; in a! => a!
+  - a! => { a = <THUNK> }
+- f: let x? = f! x?; in x! => f! x!
+- let ret? = (self: { x? = 1; y? = self.x! + 1; }) ret?; in ret.y! => ret! x! y!
+
+工作流程：
+1. string -> AST
+2. AST -> HIR (alloc ExprId)
+3. HIR -> LIR (resolve var, build graph)
+4. LIR -> Value
+
 ```mermaid
 flowchart TD
-  Start --> CtxNew[Context::new]
-  CtxNew --> CtxEval[Context::eval]
-  CtxEval --> DCtxNew[DowngradeCtx::new]
-  DCtxNew --> DCtxDowngradeRoot[DowngradeCtx::downgrade_root]
-  DCtxDowngradeRoot --> RCtxNew[ResolveCtx::new]
-  RCtxNew --> RCtxResolveRoot[ResolveCtx::resolve_root]
-  RCtxResolveRoot --> ECtxNew[EvalCtx::new]
-  ECtxNew --> ECtxEvalRoot[EvalCtx::eval_root]
-  ECtxEvalRoot --> ECtxEvalDeps[EvalCtx::eval_deps]
-  ECtxEvalDeps --> ECtxEval[EvalCtx::eval]
+  Start([Context::eval]) --> Eval[EvalContext::eval]
+  Eval --> AddNode[add node to graph]
+  AddNode --> CheckType{check expression type}
+
+  CheckType -->|AttrSet| A_EvalKeys[eval keys]
+  A_EvalKeys --> A_Construct[construct attrset]
+  A_Construct --> A_Return[return attrset]
+  A_Return --> End
+  A_EvalKeys -.->|eval| Eval
+
+  CheckType -->|List| L_Construct[construct list]
+  L_Construct --> L_Return[return list]
+  L_Return --> End
+
+  CheckType -->|HasAttr| HA_ForceAttrSet[force attrset]
+  HA_ForceAttrSet --> HA_ForceAttrPath[force attrpath]
+  HA_ForceAttrPath --> HA_Return[return bool]
+  HA_Return --> End
+  HA_ForceAttrSet -.->|eval| Eval
+  HA_ForceAttrPath -.->|eval| Eval
+
+  CheckType -->|BinOp| B_ForceLeft[force left operand]
+  B_ForceLeft --> B_ForceRight[force right operand]
+  B_ForceRight --> B_Apply[apply operator]
+  B_Apply --> B_Return[return value]
+  B_Return --> End
+  B_ForceLeft -.->|eval| Eval
+  B_ForceRight -.->|eval| Eval
+
+  CheckType -->|UnOp| U_ForceOperand[force operand]
+  U_ForceOperand --> U_Apply[apply operator]
+  U_Apply --> U_Return[return value]
+  U_Return --> End
+  U_ForceOperand -.->|eval| Eval
+
+  CheckType -->|Select| S_ForceAttrSet[force attrset]
+  S_ForceAttrSet --> S_ForceAttrPath[force attrpath]
+  S_ForceAttrPath --> S_CallEval[call eval on value]
+  S_CallEval --> S_Return[return value]
+  S_Return --> End
+  S_ForceAttrSet -.->|eval| Eval
+  S_ForceAttrPath -.->|eval| Eval
+  S_CallEval -.-> Eval
+
+  CheckType -->|If| I_ForceCond[force condition]
+  I_ForceCond --> I_Cond{condition}
+  I_Cond -->|true| I_ForceConsq[force consequence]
+  I_Cond -->|false| I_ForceAlter[force alternative]
+  I_ForceConsq --> I_CallEvalConsq[call eval on consequence]
+  I_ForceAlter --> I_CallEvalAlter[call eval on alternative]
+  I_CallEvalConsq --> I_ReturnConsq[return value]
+  I_CallEvalAlter --> I_ReturnAlter[return value]
+  I_ReturnConsq --> End
+  I_ReturnAlter --> End
+  I_ForceCond -.->|eval| Eval
+  I_ForceConsq -.->|eval| Eval
+  I_ForceAlter -.->|eval| Eval
+  I_CallEvalConsq -.-> Eval
+  I_CallEvalAlter -.-> Eval
+
+  CheckType -->|Call| C_RegArg[register argument]
+  C_RegArg --> C_ForceBody[force body]
+  C_ForceBody --> C_CallEval[call eval on body]
+  C_CallEval --> C_Return[return value]
+  C_Return --> End
+  C_ForceBody -.->|eval| Eval
+  C_CallEval -.-> Eval
+
+  CheckType -->|With| W_EnterWith[enter with]
+  W_EnterWith --> W_ForceBody[force body]
+  W_ForceBody --> W_CallEval[call eval on body]
+  W_CallEval --> W_Return[return value]
+  W_Return --> End
+  W_ForceBody -.->|eval| Eval
+  W_CallEval -.-> Eval
+
+  CheckType -->|Assert| As_ForceCond[force condition]
+  As_ForceCond --> As_Cond{condition}
+  As_Cond -->|true| As_ForceBody[force body]
+  As_Cond -->|false| As_Throw[throw Catchable]
+  As_ForceBody --> As_CallEval[call eval on body]
+  As_CallEval --> End
+  As_ForceCond -.->|eval| Eval
+  As_ForceBody -.->|eval| Eval
+  As_CallEval -.-> Eval
+
+  CheckType -->|ConcatStrings| CS_ForceParts[force string parts]
+  CS_ForceParts --> CS_Construct[construct string]
+  CS_Construct --> End
+  CS_ForceParts -.->|eval| Eval
+
+  CheckType -->|Const| Co_Return[return constant]
+  Co_Return --> End
+
+  CheckType -->|Str| St_Return[return string]
+  St_Return --> End
+
+  CheckType -->|Var| V_Lookup[lookup var]
+  V_Lookup --> V_Return[return value]
+  V_Return --> End
+
+  CheckType -->|Arg| Ar_Lookup[lookup arg]
+  Ar_Lookup --> End
+
+  CheckType -->|Func| F_Construct[construct function]
+  F_Construct --> End
+
+  CheckType -->|StrictRef| SR_Eval[eval referenced expr]
+  SR_Eval --> Eval
+
+  CheckType -->|LazyRef| LR_Resolve[resolve dynamic variable lookups of the referenced expr]
+  LR_Resolve --> LR_Contruct[construct lazy reference]
+  LR_Contruct --> End
+
+  End([return result])
 ```
diff --git a/evaluator/nixjit_context/src/downgrade.rs b/evaluator/nixjit_context/src/downgrade.rs
index 3661546..fbae341 100644
--- a/evaluator/nixjit_context/src/downgrade.rs
+++ b/evaluator/nixjit_context/src/downgrade.rs
@@ -34,7 +34,7 @@ impl DowngradeCtx<'_, '_> {
 impl DowngradeContext for DowngradeCtx<'_, '_> {
     fn new_expr(&mut self, expr: Hir) -> ExprId {
         self.irs.push(expr.into());
-        unsafe { ExprId::from_raw(self.ctx.lirs.len() + self.ctx.hirs.len() + self.irs.len() - 1) }
+        self.ctx.alloc_id()
     }
 
     fn with_expr_mut<T>(&mut self, id: ExprId, f: impl FnOnce(&mut Hir, &mut Self) -> T) -> T {
diff --git a/evaluator/nixjit_context/src/eval.rs b/evaluator/nixjit_context/src/eval.rs
index 6b1ff93..3df93fd 100644
--- a/evaluator/nixjit_context/src/eval.rs
+++ b/evaluator/nixjit_context/src/eval.rs
@@ -1,3 +1,7 @@
+#[cfg(debug_assertions)]
+use std::cell::OnceCell;
+#[cfg(not(debug_assertions))]
+use std::mem::MaybeUninit;
 use std::rc::Rc;
 
 use hashbrown::HashMap;
@@ -8,12 +12,40 @@ use nixjit_eval::{Args, EvalContext, Evaluate, StackFrame, Value};
 use nixjit_ir::ExprId;
 use nixjit_jit::JITContext;
 use nixjit_lir::Lir;
-use petgraph::visit::{Topo, Walker};
+use petgraph::prelude::DiGraph;
 
 use super::Context;
 
+#[derive(Default)]
+struct ValueCache(
+    #[cfg(debug_assertions)]
+    Option<Value>,
+    #[cfg(not(debug_assertions))]
+    MaybeUninit<Value>
+);
+
+impl ValueCache {
+    fn insert(&mut self, val: Value) {
+        #[cfg(debug_assertions)]
+        {
+            assert!(self.0.is_none());
+            let _ = self.0.insert(val);
+        }
+        #[cfg(not(debug_assertions))]
+        self.0.write(val);
+    }
+}
+
+impl Drop for ValueCache {
+    fn drop(&mut self) {
+        #[cfg(not(debug_assertions))]
+        self.0.assume_init_drop();
+    }
+}
+
 pub struct EvalCtx<'ctx, 'bump> {
     ctx: &'ctx mut Context<'bump>,
+    graph: DiGraph<ValueCache, ()>,
     stack: Vec<StackFrame>,
     with_scopes: Vec<Rc<HashMap<String, Value>>>,
 }
@@ -22,6 +54,7 @@ impl<'ctx, 'bump> EvalCtx<'ctx, 'bump> {
     pub fn new(ctx: &'ctx mut Context<'bump>) -> Self {
         Self {
             ctx,
+            graph: DiGraph::new(),
             stack: Vec::new(),
             with_scopes: Vec::new(),
         }
diff --git a/evaluator/nixjit_context/src/lib.rs b/evaluator/nixjit_context/src/lib.rs
index 91b2afb..ddaf4f5 100644
--- a/evaluator/nixjit_context/src/lib.rs
+++ b/evaluator/nixjit_context/src/lib.rs
@@ -1,4 +1,7 @@
-use std::{marker::PhantomPinned, ops::{Deref, DerefMut}};
+use std::cell::Cell;
+use std::marker::PhantomPinned;
+use std::ops::{Deref, DerefMut};
+use std::ptr::NonNull;
 
 use bumpalo::{Bump, boxed::Box};
 use hashbrown::HashMap;
@@ -10,12 +13,12 @@ use petgraph::{
 
 use nixjit_builtins::{
     Builtins, BuiltinsContext,
-    builtins::{CONSTS_LEN, GLOBAL_LEN, SCOPED_LEN},
+    builtins::{GLOBAL_LEN, SCOPED_LEN},
 };
 use nixjit_error::{Error, Result};
 use nixjit_eval::{Args, EvalContext, Value};
 use nixjit_hir::{DowngradeContext, Hir};
-use nixjit_ir::{AttrSet, Const, ExprId, Param, PrimOpId, StackIdx};
+use nixjit_ir::{AttrSet, ExprId, Param, PrimOpId, StackIdx};
 use nixjit_lir::{Lir, ResolveContext};
 
 use crate::downgrade::DowngradeCtx;
@@ -65,13 +68,14 @@ impl<'bump, T> Pin<'bump, T> {
 /// This struct orchestrates the entire Nix expression evaluation process,
 /// from parsing and semantic analysis to interpretation and JIT compilation.
 pub struct Context<'bump> {
+    ir_count: usize,
     hirs: Vec<Hir>,
     lirs: Vec<Pin<'bump, Lir>>,
     /// Maps a function's body `ExprId` to its parameter definition.
     funcs: HashMap<ExprId, Param>,
 
-    repl_scope: HashMap<String, ExprId>,
-    global_scope: HashMap<&'static str, ExprId>,
+    repl_scope: NonNull<HashMap<String, ExprId>>,
+    global_scope: NonNull<HashMap<&'static str, ExprId>>,
 
     /// A dependency graph between expressions.
     graph: DiGraphMap<ExprId, StackIdx>,
@@ -82,25 +86,24 @@ pub struct Context<'bump> {
     bump: &'bump Bump,
 }
 
+impl Drop for Context<'_> {
+    fn drop(&mut self) {
+        unsafe {
+            self.repl_scope.drop_in_place();
+            self.global_scope.drop_in_place();
+        }
+    }
+}
+
 impl<'bump> Context<'bump> {
     pub fn new(bump: &'bump Bump) -> Self {
-        let Builtins {
-            consts,
-            global,
-            scoped,
-        } = Builtins::new();
-        let global_scope = consts
+        let Builtins { global, scoped } = Builtins::new();
+        let global_scope = global
             .iter()
             .enumerate()
-            .map(|(id, (k, _))| (*k, unsafe { ExprId::from_raw(id) }))
-            .chain(
-                global
-                    .iter()
-                    .enumerate()
-                    .map(|(idx, (k, _, _))| (*k, unsafe { ExprId::from_raw(idx + CONSTS_LEN) })),
-            )
+            .map(|(idx, (k, _, _))| (*k, unsafe { ExprId::from_raw(idx) }))
             .chain(core::iter::once(("builtins", unsafe {
-                ExprId::from_raw(CONSTS_LEN + GLOBAL_LEN + SCOPED_LEN)
+                ExprId::from_raw(GLOBAL_LEN + SCOPED_LEN)
             })))
             .collect();
         let primops = global
@@ -109,47 +112,41 @@ impl<'bump> Context<'bump> {
             .chain(scoped.iter().map(|&(_, arity, f)| (arity, f)))
             .collect_array()
             .unwrap();
-        let lirs = consts
-            .into_iter()
-            .map(|(_, val)| Lir::Const(Const { val }))
-            .chain((0..global.len()).map(|idx| Lir::PrimOp(unsafe { PrimOpId::from_raw(idx) })))
+        let lirs = (0..global.len()).map(|idx| Lir::PrimOp(unsafe { PrimOpId::from_raw(idx) }))
             .chain(
                 (0..scoped.len())
                     .map(|idx| Lir::PrimOp(unsafe { PrimOpId::from_raw(idx + GLOBAL_LEN) })),
             )
             .chain(core::iter::once(Lir::AttrSet(AttrSet {
-                stcs: consts
-                    .into_iter()
-                    .enumerate()
-                    .map(|(idx, (name, _))| (name.to_string(), unsafe { ExprId::from_raw(idx) }))
-                    .chain(global.into_iter().enumerate().map(|(idx, (name, ..))| {
+                stcs: global.into_iter().enumerate().map(|(idx, (name, ..))| {
                         (name.to_string(), unsafe {
-                            ExprId::from_raw(idx + CONSTS_LEN)
+                            ExprId::from_raw(idx)
                         })
-                    }))
+                    })
                     .chain(scoped.into_iter().enumerate().map(|(idx, (name, ..))| {
                         (name.to_string(), unsafe {
-                            ExprId::from_raw(idx + CONSTS_LEN + GLOBAL_LEN)
+                            ExprId::from_raw(idx + GLOBAL_LEN)
                         })
                     }))
                     .chain(core::iter::once(("builtins".to_string(), unsafe {
-                        ExprId::from_raw(CONSTS_LEN + GLOBAL_LEN + SCOPED_LEN + 1)
+                        ExprId::from_raw(GLOBAL_LEN + SCOPED_LEN + 1)
                     })))
                     .collect(),
                 ..AttrSet::default()
             })))
             .chain(core::iter::once(Lir::Thunk(unsafe {
-                ExprId::from_raw(CONSTS_LEN + GLOBAL_LEN + SCOPED_LEN)
+                ExprId::from_raw(GLOBAL_LEN + SCOPED_LEN)
             })))
             .map(|lir| Pin::new_in(lir, bump))
             .collect();
         Self {
+            ir_count: 0,
             hirs: Vec::new(),
             lirs,
             funcs: HashMap::new(),
 
-            global_scope,
-            repl_scope: HashMap::new(),
+            global_scope: NonNull::from(bump.alloc(global_scope)),
+            repl_scope: NonNull::from(bump.alloc(HashMap::new())),
             graph: DiGraphMap::new(),
 
             primops,
@@ -207,9 +204,29 @@ impl<'bump> Context<'bump> {
         let root_expr = root.tree().expr().unwrap();
         let expr_id = self.downgrade_ctx().downgrade_root(root_expr)?;
         self.resolve_ctx().resolve_root(expr_id)?;
-        self.repl_scope.insert(ident.to_string(), expr_id);
+        unsafe { self.repl_scope.as_mut() }.insert(ident.to_string(), expr_id);
         Ok(())
     }
 }
 
+impl Context<'_> {
+    fn alloc_id(&mut self) -> ExprId {
+        self.ir_count += 1;
+        unsafe { ExprId::from_raw(self.ir_count - 1) }
+    }
+
+    fn add_dep(&mut self, from: ExprId, to: ExprId, count: &Cell<usize>) -> StackIdx {
+        if let Some(&idx) = self.graph.edge_weight(from, to) {
+            idx
+        } else {
+            let idx = count.get();
+            count.set(idx + 1);
+            let idx = unsafe { StackIdx::from_raw(idx) };
+            assert_ne!(from, to);
+            self.graph.add_edge(from, to, idx);
+            idx
+        }
+    }
+}
+
 impl BuiltinsContext for Context<'_> {}
diff --git a/evaluator/nixjit_context/src/resolve.rs b/evaluator/nixjit_context/src/resolve.rs
index 0fce511..2f9c029 100644
--- a/evaluator/nixjit_context/src/resolve.rs
+++ b/evaluator/nixjit_context/src/resolve.rs
@@ -1,11 +1,11 @@
-use std::cell::RefCell;
+use std::cell::{Cell, RefCell};
 
 use derive_more::Unwrap;
 use hashbrown::HashMap;
 
 use nixjit_error::Result;
 use nixjit_hir::Hir;
-use nixjit_ir::{Const, ExprId, Param, StackIdx};
+use nixjit_ir::{Const, ExprId, Param, PrimOpId, StackIdx};
 use nixjit_lir::{Lir, LookupResult, Resolve, ResolveContext};
 use replace_with::replace_with_and_return;
 
@@ -30,33 +30,22 @@ enum Ir {
     Lir(Lir),
 }
 
-impl Ir {
-    unsafe fn unwrap_hir_unchecked(self) -> Hir {
-        if let Self::Hir(hir) = self {
-            hir
-        } else {
-            unsafe { core::hint::unreachable_unchecked() }
-        }
-    }
-}
-
 pub struct ResolveCtx<'ctx, 'bump> {
     ctx: &'ctx mut Context<'bump>,
     irs: Vec<Pin<'bump, RefCell<Ir>>>,
     scopes: Vec<Scope<'ctx>>,
     has_with: bool,
     with_used: bool,
-    closures: Vec<(ExprId, Option<ExprId>, usize)>,
+    closures: Vec<(ExprId, Option<ExprId>, Cell<usize>)>,
     current_expr: Option<ExprId>,
 }
 
 impl<'ctx, 'bump> ResolveCtx<'ctx, 'bump> {
     pub fn new(ctx: &'ctx mut Context<'bump>) -> Self {
-        let ctx_mut = unsafe { &mut *(ctx as *mut Context) };
         Self {
             scopes: vec![
-                Scope::Builtins(&ctx.global_scope),
-                Scope::Repl(&ctx.repl_scope),
+                Scope::Builtins(unsafe { ctx.global_scope.as_ref() }),
+                Scope::Repl(unsafe { ctx.repl_scope.as_ref() }),
             ],
             has_with: false,
             with_used: false,
@@ -65,7 +54,7 @@ impl<'ctx, 'bump> ResolveCtx<'ctx, 'bump> {
                 .map(|hir| Ir::Hir(hir).into())
                 .map(|ir| Pin::new_in(ir, ctx.bump))
                 .collect(),
-            ctx: ctx_mut,
+            ctx,
             closures: Vec::new(),
             current_expr: None,
         }
@@ -80,33 +69,10 @@ impl<'ctx, 'bump> ResolveCtx<'ctx, 'bump> {
         }
     }
 
-    fn get_ir_mut(&mut self, id: ExprId) -> &mut RefCell<Ir> {
-        let idx = unsafe { id.raw() } - self.ctx.lirs.len();
-        if cfg!(debug_assertions) {
-            self.irs.get_mut(idx).unwrap()
-        } else {
-            unsafe { self.irs.get_unchecked_mut(idx) }
-        }
-    }
-
-    fn add_dep(&mut self, from: ExprId, to: ExprId, count: &mut usize) -> StackIdx {
-        if let Some(&idx) = self.ctx.graph.edge_weight(from, to) {
-            idx
-        } else {
-            *count += 1;
-            let idx = unsafe { StackIdx::from_raw(*count - 1) };
-            assert_ne!(from, to);
-            self.ctx.graph.add_edge(from, to, idx);
-            idx
-        }
-    }
-
     fn new_lir(&mut self, lir: Lir) -> ExprId {
-        self.irs.push(Pin::new_in(
-            RefCell::new(Ir::Lir(lir)),
-            self.ctx.bump,
-        ));
-        unsafe { ExprId::from_raw(self.ctx.lirs.len() + self.irs.len() - 1) }
+        self.irs
+            .push(Pin::new_in(RefCell::new(Ir::Lir(lir)), self.ctx.bump));
+        self.ctx.alloc_id()
     }
 }
 
@@ -115,7 +81,7 @@ impl ResolveContext for ResolveCtx<'_, '_> {
         let prev_expr = self.current_expr.replace(expr);
         let result = unsafe {
             let ctx = &mut *(self as *mut Self);
-            let ir = &mut self.get_ir_mut(expr);
+            let ir = self.get_ir(expr);
             if !matches!(ir.try_borrow().as_deref(), Ok(Ir::Hir(_))) {
                 return Ok(());
             }
@@ -126,7 +92,7 @@ impl ResolveContext for ResolveCtx<'_, '_> {
                         val: nixjit_value::Const::Null,
                     }))
                 },
-                |ir| match ir.unwrap_hir_unchecked().resolve(ctx) {
+                |ir| match ir.unwrap_hir().resolve(ctx) {
                     Ok(lir) => (Ok(()), Ir::Lir(lir)),
                     Err(err) => (
                         Err(err),
@@ -141,12 +107,8 @@ impl ResolveContext for ResolveCtx<'_, '_> {
         result
     }
 
-    fn resolve_call(&mut self, func: ExprId, arg: ExprId) -> Result<()> {
-        todo!()
-    }
-
     fn resolve_root(mut self, expr: ExprId) -> Result<()> {
-        self.closures.push((expr, None, 0));
+        self.closures.push((expr, None, Cell::new(0)));
         let ret = self.resolve(expr);
         if ret.is_ok() {
             self.ctx.lirs.extend(
@@ -167,17 +129,17 @@ impl ResolveContext for ResolveCtx<'_, '_> {
         for scope in self.scopes.iter().rev() {
             match scope {
                 Scope::Builtins(scope) => {
-                    if let Some(&expr) = scope.get(&name) {
-                        return LookupResult::Expr(expr);
+                    if let Some(&primop) = scope.get(&name) {
+                        return LookupResult::PrimOp(primop);
                     }
                 }
                 Scope::Let(scope) | &Scope::Repl(scope) => {
                     if let Some(&dep) = scope.get(name) {
-                        let (expr, _, deps) = unsafe { &mut *(self as *mut Self) }
+                        let (expr, _, deps) = self
                             .closures
-                            .last_mut()
+                            .last()
                             .unwrap();
-                        let idx = self.add_dep(*expr, dep, deps);
+                        let idx = self.ctx.add_dep(*expr, dep, deps);
                         return LookupResult::Stack(idx);
                     }
                 }
@@ -186,19 +148,18 @@ impl ResolveContext for ResolveCtx<'_, '_> {
                         // This is an outer function's parameter, treat as dependency
                         // We need to find the corresponding parameter expression to create dependency
                         // For now, we need to handle this case by creating a dependency to the parameter
-                        let mut iter = unsafe { &mut *(self as *mut Self) }
-                            .closures
-                            .iter_mut()
-                            .rev()
-                            .take(closure_depth + 1)
-                            .rev();
+                        let mut iter = self.closures.iter().rev().take(closure_depth + 1).rev();
                         let Some((func, Some(arg), count)) = iter.next() else {
                             unreachable!()
                         };
-                        let mut cur = self.add_dep(*func, *arg, count);
+                        let mut cur = self.ctx.add_dep(*func, *arg, count);
                         for (func, _, count) in iter {
-                            let idx = self.new_lir(Lir::StackRef(cur));
-                            cur = self.add_dep(*func, idx, count);
+                            self.irs.push(Pin::new_in(
+                                RefCell::new(Ir::Lir(Lir::StackRef(cur))),
+                                self.ctx.bump,
+                            ));
+                            let idx = self.ctx.alloc_id();
+                            cur = self.ctx.add_dep(*func, idx, count);
                         }
                         return LookupResult::Stack(cur);
                     }
@@ -215,12 +176,10 @@ impl ResolveContext for ResolveCtx<'_, '_> {
     }
 
     fn lookup_arg(&mut self) -> StackIdx {
-        let Some((func, Some(arg), count)) =
-            unsafe { &mut *(self as *mut Self) }.closures.last_mut()
-        else {
+        let Some((func, Some(arg), count)) = self.closures.last() else {
             unreachable!()
         };
-        self.add_dep(*func, *arg, count)
+        self.ctx.add_dep(*func, *arg, count)
     }
 
     fn new_func(&mut self, body: ExprId, param: Param) {
@@ -255,7 +214,7 @@ impl ResolveContext for ResolveCtx<'_, '_> {
         f: impl FnOnce(&mut Self) -> T,
     ) -> T {
         let arg = self.new_lir(Lir::Arg(nixjit_ir::Arg));
-        self.closures.push((func, Some(arg), 0));
+        self.closures.push((func, Some(arg), Cell::new(0)));
         self.scopes.push(Scope::Arg(ident));
         let res = f(self);
         self.scopes.pop();
diff --git a/evaluator/nixjit_eval/src/lib.rs b/evaluator/nixjit_eval/src/lib.rs
index 9373dc2..f1849ef 100644
--- a/evaluator/nixjit_eval/src/lib.rs
+++ b/evaluator/nixjit_eval/src/lib.rs
@@ -330,13 +330,7 @@ impl<Ctx: EvalContext> Evaluate<Ctx> for ir::Str {
 impl<Ctx: EvalContext> Evaluate<Ctx> for ir::Const {
     /// Evaluates a `Const` literal into its corresponding `Value` variant.
     fn eval(&self, _: &mut Ctx) -> Result<Value> {
-        let result = match self.val {
-            Const::Null => Value::Null,
-            Const::Int(x) => Value::Int(x),
-            Const::Float(x) => Value::Float(x),
-            Const::Bool(x) => Value::Bool(x),
-        };
-        Ok(result)
+        Ok(self.val.into())
     }
 }
 
diff --git a/evaluator/nixjit_eval/src/value/mod.rs b/evaluator/nixjit_eval/src/value/mod.rs
index 968f1a3..e46e7e3 100644
--- a/evaluator/nixjit_eval/src/value/mod.rs
+++ b/evaluator/nixjit_eval/src/value/mod.rs
@@ -76,6 +76,17 @@ impl Debug for Value {
     }
 }
 
+impl From<Const> for Value {
+    fn from(value: nixjit_value::Const) -> Self {
+        match value {
+            Const::Null => Value::Null,
+            Const::Int(x) => Value::Int(x),
+            Const::Float(x) => Value::Float(x),
+            Const::Bool(x) => Value::Bool(x),
+        }
+    }
+}
+
 impl Value {
     pub const INT: u64 = 0;
     pub const FLOAT: u64 = 1;
diff --git a/evaluator/nixjit_lir/src/lib.rs b/evaluator/nixjit_lir/src/lib.rs
index 809052a..3196b33 100644
--- a/evaluator/nixjit_lir/src/lib.rs
+++ b/evaluator/nixjit_lir/src/lib.rs
@@ -52,7 +52,7 @@ ir! {
 pub enum LookupResult {
     Stack(StackIdx),
     /// The variable was found and resolved to a specific expression.
-    Expr(ExprId),
+    PrimOp(ExprId),
     /// The variable could not be resolved statically, likely due to a `with` expression.
     /// The lookup must be performed dynamically at evaluation time.
     Unknown,
@@ -71,8 +71,6 @@ pub trait ResolveContext {
     /// Triggers the resolution of a given expression.
     fn resolve(&mut self, expr: ExprId) -> Result<()>;
 
-    fn resolve_call(&mut self, func: ExprId, arg: ExprId) -> Result<()>;
-
     fn resolve_root(self, expr: ExprId) -> Result<()>;
 
     /// Looks up a variable by name in the current scope.
@@ -233,7 +231,6 @@ impl<Ctx: ResolveContext> Resolve<Ctx> for Call {
     fn resolve(self, ctx: &mut Ctx) -> Result<Lir> {
         ctx.resolve(self.func)?;
         ctx.resolve(self.arg)?;
-        ctx.resolve_call(self.func, self.arg)?;
         Ok(self.to_lir())
     }
 }
@@ -280,7 +277,7 @@ impl<Ctx: ResolveContext> Resolve<Ctx> for Var {
         use LookupResult::*;
         match ctx.lookup(&self.sym) {
             Stack(idx) => Ok(Lir::StackRef(idx)),
-            Expr(expr) => Ok(Lir::ExprRef(expr)),
+            PrimOp(id) => Ok(Lir::ExprRef(id)),
             Unknown => Ok(self.to_lir()),
             NotFound => Err(Error::resolution_error(format!(
                 "undefined variable '{}'",
diff --git a/evaluator/nixjit_macros/src/builtins.rs b/evaluator/nixjit_macros/src/builtins.rs
index 3c1086b..2ea18c9 100644
--- a/evaluator/nixjit_macros/src/builtins.rs
+++ b/evaluator/nixjit_macros/src/builtins.rs
@@ -18,7 +18,7 @@ use proc_macro::TokenStream;
 use proc_macro2::Span;
 use quote::{ToTokens, format_ident, quote};
 use syn::{
-    FnArg, Item, ItemFn, ItemMod, Pat, PatIdent, PatType, Type, Visibility, parse_macro_input,
+    parse_macro_input, FnArg, Item, ItemConst, ItemFn, ItemMod, Pat, PatIdent, PatType, Type, Visibility
 };
 
 /// The implementation of the `#[builtins]` macro.
@@ -40,7 +40,6 @@ pub fn builtins_impl(input: TokenStream) -> TokenStream {
     };
 
     let mut pub_item_mod = Vec::new();
-    let mut consts = Vec::new();
     let mut global = Vec::new();
     let mut scoped = Vec::new();
     let mut wrappers = Vec::new();
@@ -49,20 +48,17 @@ pub fn builtins_impl(input: TokenStream) -> TokenStream {
     for item in &items {
         match item {
             Item::Const(item_const) => {
-                // Handle `const` definitions. These are exposed as constants in Nix.
-                let name_str = item_const
-                    .ident
-                    .to_string()
-                    .from_case(Case::UpperSnake)
-                    .to_case(Case::Camel);
-                let const_name = &item_const.ident;
-                consts.push(quote! { (#name_str, builtins::#const_name) });
-                pub_item_mod.push(
-                    quote! {
-                        pub #item_const
-                    }
-                    .into(),
-                );
+                let (primop, wrapper) = match generate_const_wrapper(item_const) {
+                    Ok(result) => result,
+                    Err(e) => return e.to_compile_error().into(),
+                };
+                // Public functions are added to the global scope, private ones to a scoped set.
+                if matches!(item_const.vis, Visibility::Public(_)) {
+                    global.push(primop);
+                } else {
+                    scoped.push(primop);
+                }
+                wrappers.push(wrapper);
             }
             Item::Fn(item_fn) => {
                 // Handle function definitions. These become primops.
@@ -90,7 +86,6 @@ pub fn builtins_impl(input: TokenStream) -> TokenStream {
         }
     }
 
-    let consts_len = consts.len();
     let global_len = global.len();
     let scoped_len = scoped.len();
 
@@ -100,15 +95,12 @@ pub fn builtins_impl(input: TokenStream) -> TokenStream {
         #visibility mod #mod_name {
             #(#pub_item_mod)*
             #(#wrappers)*
-            pub const CONSTS_LEN: usize = #consts_len;
             pub const GLOBAL_LEN: usize = #global_len;
             pub const SCOPED_LEN: usize = #scoped_len;
         }
 
         /// A struct containing all the built-in constants and functions.
         pub struct Builtins<Ctx: BuiltinsContext> {
-            /// Constant values available in the global scope.
-            pub consts: [(&'static str, ::nixjit_value::Const); #mod_name::CONSTS_LEN],
             /// Global functions available in the global scope.
             pub global: [(&'static str, usize, fn(&mut Ctx, ::nixjit_eval::Args) -> ::nixjit_error::Result<::nixjit_eval::Value>); #mod_name::GLOBAL_LEN],
             /// Scoped functions, typically available under the `builtins` attribute set.
@@ -119,7 +111,6 @@ pub fn builtins_impl(input: TokenStream) -> TokenStream {
             /// Creates a new instance of the `Builtins` struct.
             pub fn new() -> Self {
                 Self {
-                    consts: [#(#consts,)*],
                     global: [#(#global,)*],
                     scoped: [#(#scoped,)*],
                 }
@@ -130,6 +121,33 @@ pub fn builtins_impl(input: TokenStream) -> TokenStream {
     output.into()
 }
 
+fn generate_const_wrapper(
+    item_const: &ItemConst,
+) -> syn::Result<(proc_macro2::TokenStream, proc_macro2::TokenStream)> {
+    let const_name = &item_const.ident;
+    let const_val =  &item_const.expr;
+    let name_str = const_name
+        .to_string()
+        .from_case(Case::UpperSnake)
+        .to_case(Case::Camel);
+    let const_name = format_ident!("{name_str}");
+    let wrapper_name = format_ident!("wrapper_{}", const_name);
+    let mod_name = format_ident!("builtins");
+
+    let fn_type = quote! { fn(&mut Ctx, ::nixjit_eval::Args) -> ::nixjit_error::Result<::nixjit_eval::Value> };
+
+    // The primop metadata tuple: (name, arity, wrapper_function_pointer)
+    let primop = quote! { (#name_str, 0, #mod_name::#wrapper_name as #fn_type) };
+
+    // The generated wrapper function.
+    let wrapper = quote! {
+        pub fn #wrapper_name<Ctx: BuiltinsContext>(ctx: &mut Ctx, mut args: ::nixjit_eval::Args) -> ::nixjit_error::Result<::nixjit_eval::Value> {
+            Ok(#const_val.into())
+        }
+    };
+
+    Ok((primop, wrapper))
+}
 /// Generates the primop metadata and the wrapper function for a single user-defined function.
 fn generate_primop_wrapper(
     item_fn: &ItemFn,
@@ -166,7 +184,7 @@ fn generate_primop_wrapper(
     };
 
     // Collect the remaining arguments.
-    let arg_pats: Vec<_> = user_args.rev().collect();
+    let arg_pats: Vec<_> = user_args.collect();
     let arg_count = arg_pats.len();
 
     let arg_unpacks = arg_pats.iter().enumerate().map(|(i, arg)| {
@@ -177,7 +195,7 @@ fn generate_primop_wrapper(
         };
 
         quote! {
-            let #arg_name: #arg_ty = args.pop().ok_or_else(|| ::nixjit_error::Error::eval_error("Not enough arguments provided".to_string()))?
+            let #arg_name: #arg_ty = args.next().ok_or_else(|| ::nixjit_error::Error::eval_error("Not enough arguments provided".to_string()))?
                 .try_into().map_err(|e| ::nixjit_error::Error::eval_error(format!("Argument type conversion failed: {}", e)))?;
         }
     });
@@ -192,7 +210,6 @@ fn generate_primop_wrapper(
             }
             _ => unreachable!(),
         })
-        .rev()
         .collect();
 
     // Construct the argument list for the final call.
@@ -232,6 +249,8 @@ fn generate_primop_wrapper(
             if args.len() != #arg_count {
                 return Err(::nixjit_error::Error::eval_error(format!("Function '{}' expects {} arguments, but received {}", #name_str, #arg_count, args.len())));
             }
+
+            let mut args = args.into_iter();
             #(#arg_unpacks)*
 
             #call_expr