diff --git a/src/bin/scc.rs b/src/bin/scc.rs
index c617e0e..ca2d044 100644
--- a/src/bin/scc.rs
+++ b/src/bin/scc.rs
@@ -39,7 +39,7 @@ fn main() -> Result<()> {
                 }
                 let expr = root.tree().expr().unwrap();
                 let downgraded = unwrap!(downgrade(expr));
-                println!("{:?}", downgraded.graph);
+                println!("{:?}", downgraded);
             }
             Err(ReadlineError::Interrupted) => {
                 println!("CTRL-C");
diff --git a/src/engine/mod.rs b/src/engine/mod.rs
index 4527719..fe95a73 100644
--- a/src/engine/mod.rs
+++ b/src/engine/mod.rs
@@ -3,11 +3,11 @@ use std::rc::Rc;
 use hashbrown::HashSet;
 use priority_queue::PriorityQueue;
 
-use crate::env::VmEnv;
+use crate::env::Env;
 use crate::error::Result;
 use crate::eval::Evaluate;
 use crate::ir::{Dep, Downgraded, Ir, SccNode};
-use crate::ty::internal::{self as i, ThunkRef};
+use crate::ty::internal as i;
 use crate::ty::public::Value;
 
 #[cfg(test)]
@@ -43,38 +43,46 @@ impl Engine {
     }
 
     pub fn eval(&mut self, graph: Vec<SccNode>) -> Result<Value> {
-        let mut env = VmEnv::new();
+        let mut env = Env::new();
         let last = graph.last().unwrap().members[0];
         for SccNode { members, .. } in graph.into_iter() {
-            // TODO:
-            assert!(members.len() == 1);
-            for member in members.into_iter() {
-                let val = self.thunks[member].clone().eval(self, &mut env)?;
-                env.insert_cache(member, val);
+            if members.len() == 1 {
+                for member in members.into_iter() {
+                    let val = self.thunks[member].clone().eval(self, &mut env)?;
+                    env.insert_cache(member, val);
+                }
+            } else {
+                todo!();
+                for member in members.into_iter() {
+                    let val = self.thunks[member].clone().eval(self, &mut env)?;
+                    env.insert_cache(member, val);
+                }
             }
         }
         env.lookup_cache(last, |_| unreachable!()).map(|mut val| {
             Ok(val
-                .force(self, &mut env)?
                 .to_public(self, &mut HashSet::new()))
         })?
     }
 
-    pub fn eval_thunk(&mut self, idx: usize, env: &mut VmEnv) -> Result<i::Value> {
-        self.thunks[idx].clone().eval(self, env)
+    pub fn eval_thunk(&mut self, idx: usize, env: &mut Env) -> Result<i::Value> {
+        let self_mut = unsafe { &mut *(self as *mut Self) };
+        self.thunks[idx].eval(self_mut, env)
     }
 
-    pub fn eval_func_deps(&mut self, idx: usize, env: &mut VmEnv) -> Result<()> {
+    pub fn eval_func_deps(&mut self, idx: usize, env: &mut Env) -> Result<()> {
         for dep in self.func_deps[idx - self.func_offset].clone() {
             match dep {
                 Dep::Arg(idx) => {
-                    if let i::Value::Thunk(ThunkRef { idx }) = env.lookup_arg(idx) {
-                        let val = self.thunks[idx].clone().eval(self, env)?;
+                    if let i::Value::Thunk(idx) = env.lookup_arg(idx) {
+                        let self_mut = unsafe { &mut *(self as *mut Self) };
+                        let val = self.thunks[idx].eval(self_mut, env)?;
                         env.insert_cache(idx, val)
                     }
                 }
                 Dep::Thunk(idx) => {
-                    let val = self.thunks[idx].clone().eval(self, env)?;
+                    let self_mut = unsafe { &mut *(self as *mut Self) };
+                    let val = self.thunks[idx].eval(self_mut, env)?;
                     env.insert_cache(idx, val)
                 }
             }
@@ -86,7 +94,7 @@ impl Engine {
 enum Thunk {
     Expr(Ir),
     Compiling,
-    Compiled(fn(Rc<VmEnv>) -> Value),
+    Compiled(fn(Rc<Env>) -> Value),
 }
 
 impl Thunk {
diff --git a/src/engine/test.rs b/src/engine/test.rs
index 198fdff..50d793a 100644
--- a/src/engine/test.rs
+++ b/src/engine/test.rs
@@ -154,7 +154,7 @@ fn test_attrs() {
         "rec { a = 1; b = a; }",
         attrs! {
             symbol!("a") => int!(1),
-            symbol!("b") => thunk!()
+            symbol!("b") => int!(1)
         },
     );
     test_expr("{ a = 1; }.a", int!(1));
@@ -196,6 +196,7 @@ fn test_let() {
         r#"let b = "c"; in { a.b = 1; } // { a."a${b}" = 2; }"#,
         attrs! { symbol!("a") => attrs!{ symbol!("ac") => int!(2) } },
     );
+    test_expr("let f = (let f = n: let a = n; f = x: a + x; in f; in f 1); in f 0", int!(1));
 }
 
 #[test]
diff --git a/src/env.rs b/src/env.rs
index 3463f6b..9ed9920 100644
--- a/src/env.rs
+++ b/src/env.rs
@@ -6,10 +6,10 @@ use hashbrown::HashMap;
 
 use crate::error::{Error, Result};
 use crate::stack::Stack;
-use crate::ty::internal::{EnvRef, Value};
+use crate::ty::internal::Value;
 
 #[derive(Clone)]
-pub struct VmEnv {
+pub struct Env {
     cache: Vec<HashMap<usize, Value>>,
     with: Vec<Rc<HashMap<EcoString, Value>>>,
     args: Vec<Value>,
@@ -38,7 +38,7 @@ pub enum Type {
     With,
 }
 
-impl VmEnv {
+impl Env {
     pub fn new() -> Self {
         Self {
             cache: Vec::from([HashMap::new()]),
@@ -66,7 +66,7 @@ impl VmEnv {
     pub fn lookup_cache(
         &mut self,
         idx: usize,
-        f: impl FnOnce(&mut VmEnv) -> Result<Value>,
+        f: impl FnOnce(&mut Env) -> Result<Value>,
     ) -> Result<Value> {
         for level in self.cache.iter().rev() {
             if let Some(ret) = level.get(&idx) {
@@ -99,6 +99,10 @@ impl VmEnv {
         self.args.split_off(self.args.len() - len)
     }
 
+    pub fn reserve_args(&mut self, len: usize) {
+        self.args.reserve(len);
+    }
+
     pub fn enter_args(&mut self, args: Vec<Value>) {
         self.args.extend(args);
     }
diff --git a/src/eval/jit/compile.rs b/src/eval/jit/compile.rs
index ba5d5a6..446b494 100644
--- a/src/eval/jit/compile.rs
+++ b/src/eval/jit/compile.rs
@@ -4,38 +4,204 @@ use crate::ir::*;
 use crate::ty::common as c;
 use crate::ty::internal::Value;
 
-use super::JITContext;
+use super::{JITContext, ValueTag};
 
 pub trait JITCompile {
-    fn compile<'gc>(self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc>;
+    fn compile<'gc>(&self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc>;
 }
 
 impl JITCompile for Attrs {
-    fn compile<'gc>(self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
+    fn compile<'gc>(&self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
         todo!()
     }
 }
 
 impl JITCompile for List {
-    fn compile<'gc>(self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
+    fn compile<'gc>(&self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
         todo!()
     }
 }
 
 impl JITCompile for HasAttr {
-    fn compile<'gc>(self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
+    fn compile<'gc>(&self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
         todo!()
     }
 }
 
 impl JITCompile for BinOp {
-    fn compile<'gc>(self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
-        todo!()
+    fn compile<'gc>(&self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
+        use ValueTag::*;
+        use BinOpKind::*;
+        let lhs = self.lhs.compile(ctx, func);
+        let rhs = self.rhs.compile(ctx, func);
+        let lhs_tag = ctx.get_tag(lhs);
+        let rhs_tag = ctx.get_tag(rhs);
+        let tag = ctx
+            .builder
+            .build_int_add(
+                lhs_tag.const_shl(ctx.helpers.const_int(8)),
+                rhs_tag,
+                "calc_tag",
+            )
+            .unwrap();
+        let ret = ctx.context.append_basic_block(func, "fallback");
+        let res = ctx
+            .builder
+            .build_alloca(ctx.helpers.value_type, "res_alloca")
+            .unwrap();
+        match self.kind {
+            Add => {
+                let int_int = ctx.context.append_basic_block(func, "int_int");
+                let int_float = ctx.context.append_basic_block(func, "int_float");
+                let float_int = ctx.context.append_basic_block(func, "float_int");
+                let float_float = ctx.context.append_basic_block(func, "float_float");
+                let fallback = ctx.context.append_basic_block(func, "fallback");
+                ctx.builder
+                    .build_switch(
+                        tag,
+                        fallback,
+                        &[
+                            (
+                                ctx.helpers.const_int(((Int as i64) << 8) + Int as i64),
+                                int_int,
+                            ),
+                            (
+                                ctx.helpers.const_int(((Int as i64) << 8) + Float as i64),
+                                int_float,
+                            ),
+                            (
+                                ctx.helpers.const_int(((Float as i64) << 8) + Int as i64),
+                                float_int,
+                            ),
+                            (
+                                ctx.helpers.const_int(((Float as i64) << 8) + Float as i64),
+                                float_float,
+                            ),
+                        ],
+                    )
+                    .unwrap();
+                ctx.builder.position_at_end(int_int);
+                let val = ctx
+                    .builder
+                    .build_int_add(ctx.get_int(lhs), ctx.get_int(rhs), "add")
+                    .unwrap();
+                ctx.builder
+                    .build_store(
+                        res,
+                        ctx.helpers.value_type.const_named_struct(&[
+                            ctx.helpers.const_int(Int as i64).into(),
+                            val.into(),
+                        ]),
+                    )
+                    .unwrap();
+                ctx.builder.position_at_end(int_float);
+                let val = ctx
+                    .builder
+                    .build_float_add(
+                        ctx.builder
+                            .build_signed_int_to_float(
+                                ctx.get_int(lhs),
+                                ctx.helpers.float_type,
+                                "lhs_to_float",
+                            )
+                            .unwrap(),
+                        ctx.get_float(rhs),
+                        "add",
+                    )
+                    .unwrap();
+                ctx.builder
+                    .build_store(
+                        res,
+                        ctx.helpers.value_type.const_named_struct(&[
+                            ctx.helpers.const_int(Float as i64).into(),
+                            val.into(),
+                        ]),
+                    )
+                    .unwrap();
+                ctx.builder.position_at_end(float_int);
+                let val = ctx
+                    .builder
+                    .build_float_add(
+                        ctx.get_float(lhs),
+                        ctx.builder
+                            .build_signed_int_to_float(
+                                ctx.get_int(rhs),
+                                ctx.helpers.float_type,
+                                "rhs_to_float",
+                            )
+                            .unwrap(),
+                        "add",
+                    )
+                    .unwrap();
+                ctx.builder
+                    .build_store(
+                        res,
+                        ctx.helpers.value_type.const_named_struct(&[
+                            ctx.helpers.const_int(Float as i64).into(),
+                            val.into(),
+                        ]),
+                    )
+                    .unwrap();
+                ctx.builder.position_at_end(int_int);
+                let val = ctx
+                    .builder
+                    .build_float_add(ctx.get_float(lhs), ctx.get_float(rhs), "add")
+                    .unwrap();
+                ctx.builder
+                    .build_store(
+                        res,
+                        ctx.helpers.value_type.const_named_struct(&[
+                            ctx.helpers.const_int(Float as i64).into(),
+                            val.into(),
+                        ]),
+                    )
+                    .unwrap();
+                ctx.builder.position_at_end(fallback);
+            }
+            Or => {
+                let bool_bool = ctx.context.append_basic_block(func, "int_int");
+                let fallback = ctx.context.append_basic_block(func, "fallback");
+                ctx.builder
+                    .build_switch(
+                        tag,
+                        fallback,
+                        &[
+                            (
+                                ctx.helpers.const_int(((Bool as i64) << 8) + Bool as i64),
+                                bool_bool,
+                            ),
+                        ],
+                    )
+                    .unwrap();
+                ctx.builder.position_at_end(bool_bool);
+                let val = ctx
+                    .builder
+                    .build_or(ctx.get_bool(lhs), ctx.get_bool(rhs), "or")
+                    .unwrap();
+                ctx.builder
+                    .build_store(
+                        res,
+                        ctx.helpers.value_type.const_named_struct(&[
+                            ctx.helpers.const_int(Bool as i64).into(),
+                            val.into(),
+                        ]),
+                    )
+                    .unwrap();
+                ctx.builder.position_at_end(fallback);
+            }
+            _ => todo!()
+        }
+        ctx.builder.position_at_end(ret);
+        ctx.builder
+            .build_load(ctx.helpers.value_type, res, "load_res")
+            .unwrap()
+            .try_into()
+            .unwrap()
     }
 }
 
 impl JITCompile for UnOp {
-    fn compile<'gc>(self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
+    fn compile<'gc>(&self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
         todo!();
         let rhs = self.rhs.compile(ctx, func);
         let tag = ctx.get_tag(rhs);
@@ -57,55 +223,55 @@ impl JITCompile for UnOp {
 }
 
 impl JITCompile for Select {
-    fn compile<'gc>(self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
+    fn compile<'gc>(&self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
         todo!()
     }
 }
 
 impl JITCompile for If {
-    fn compile<'gc>(self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
+    fn compile<'gc>(&self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
         todo!()
     }
 }
 
 impl JITCompile for LoadFunc {
-    fn compile<'gc>(self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
+    fn compile<'gc>(&self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
         todo!()
     }
 }
 
 impl JITCompile for Call {
-    fn compile<'gc>(self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
+    fn compile<'gc>(&self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
         todo!()
     }
 }
 
 impl JITCompile for Let {
-    fn compile<'gc>(self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
+    fn compile<'gc>(&self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
         todo!()
     }
 }
 
 impl JITCompile for With {
-    fn compile<'gc>(self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
+    fn compile<'gc>(&self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
         todo!()
     }
 }
 
 impl JITCompile for Assert {
-    fn compile<'gc>(self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
+    fn compile<'gc>(&self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
         todo!()
     }
 }
 
 impl JITCompile for ConcatStrings {
-    fn compile<'gc>(self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
+    fn compile<'gc>(&self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
         todo!()
     }
 }
 
 impl JITCompile for Const {
-    fn compile<'gc>(self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
+    fn compile<'gc>(&self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
         use c::Const::*;
         match self.val {
             Bool(x) => ctx.helpers.new_bool(x),
@@ -117,37 +283,37 @@ impl JITCompile for Const {
 }
 
 impl JITCompile for String {
-    fn compile<'gc>(self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
+    fn compile<'gc>(&self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
         todo!()
     }
 }
 
 impl JITCompile for Var {
-    fn compile<'gc>(self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
+    fn compile<'gc>(&self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
         todo!()
     }
 }
 
 impl JITCompile for Arg {
-    fn compile<'gc>(self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
+    fn compile<'gc>(&self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
         todo!()
     }
 }
 
 impl JITCompile for LetVar {
-    fn compile<'gc>(self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
+    fn compile<'gc>(&self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
         todo!()
     }
 }
 
 impl JITCompile for Thunk {
-    fn compile<'gc>(self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
+    fn compile<'gc>(&self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
         todo!()
     }
 }
 
 impl JITCompile for Path {
-    fn compile<'gc>(self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
+    fn compile<'gc>(&self, ctx: &JITContext<'gc>, func: FunctionValue<'gc>) -> StructValue<'gc> {
         todo!()
     }
 }
diff --git a/src/eval/jit/helpers.rs b/src/eval/jit/helpers.rs
index f7fb59c..3458cad 100644
--- a/src/eval/jit/helpers.rs
+++ b/src/eval/jit/helpers.rs
@@ -7,8 +7,9 @@ use inkwell::module::Module;
 use inkwell::types::{FloatType, FunctionType, IntType, PointerType, StructType};
 use inkwell::values::{BasicValueEnum, FloatValue, FunctionValue, IntValue, StructValue};
 
-use crate::env::VmEnv;
+use crate::env::Env;
 use crate::eval::Engine;
+use crate::ty::internal::Value;
 
 use super::{JITContext, JITValue, JITValueData, ValueTag};
 
@@ -54,7 +55,7 @@ impl<'ctx> Helpers<'ctx> {
 
         let new_thunk = module.add_function(
             "new_thunk",
-            value_type.fn_type(&[ptr_type.into()], false),
+            value_type.fn_type(&[ptr_type.into(), ptr_type.into()], false),
             None,
         );
         let debug = module.add_function(
@@ -102,7 +103,7 @@ impl<'ctx> Helpers<'ctx> {
         let call = module.add_function(
             "call",
             value_type.fn_type(
-                &[value_type.into(), value_type.into(), ptr_type.into()],
+                &[value_type.into(), ptr_type.into(), ptr_type.into(), ptr_type.into()],
                 false,
             ),
             None,
@@ -234,11 +235,11 @@ extern "C" fn helper_debug(value: JITValue) {
     dbg!(value.tag);
 }
 
-extern "C" fn helper_capture_env(thunk: JITValue, env: *const VmEnv) {
+extern "C" fn helper_capture_env(thunk: JITValue, env: *const Env) {
     todo!()
 }
 
-extern "C" fn helper_neg(rhs: JITValue, _env: *const VmEnv) -> JITValue {
+extern "C" fn helper_neg(rhs: JITValue, _env: *const Env) -> JITValue {
     use ValueTag::*;
     match rhs.tag {
         Int => JITValue {
@@ -257,7 +258,7 @@ extern "C" fn helper_neg(rhs: JITValue, _env: *const VmEnv) -> JITValue {
     }
 }
 
-extern "C" fn helper_not(rhs: JITValue, _env: *const VmEnv) -> JITValue {
+extern "C" fn helper_not(rhs: JITValue, _env: *const Env) -> JITValue {
     use ValueTag::*;
     match rhs.tag {
         Bool => JITValue {
@@ -338,21 +339,22 @@ extern "C" fn helper_or(lhs: JITValue, rhs: JITValue) -> JITValue {
     }
 }
 
-extern "C" fn helper_call(func: JITValue, arg: JITValue, engine: *mut Engine) -> JITValue {
+extern "C" fn helper_call(func: JITValue, args: Box<[JITValue]>, engine: NonNull<Engine>, env: NonNull<Env>) -> JITValue {
+    let func = Value::from(func);
     todo!()
 }
 
-extern "C" fn helper_arg(idx: usize, env: *const VmEnv) -> JITValue {
+extern "C" fn helper_arg(idx: usize, env: *const Env) -> JITValue {
     let env = unsafe { env.as_ref() }.unwrap();
     let val: JITValue = env.lookup_arg(idx).clone().into();
     val
 }
 
-extern "C" fn helper_lookup_let(level: usize, idx: usize, env: *const VmEnv) -> JITValue {
+extern "C" fn helper_lookup_let(level: usize, idx: usize, env: *const Env) -> JITValue {
     todo!()
 }
 
-extern "C" fn helper_lookup(sym: usize, env: *const VmEnv) -> JITValue {
+extern "C" fn helper_lookup(sym: usize, env: *const Env) -> JITValue {
     todo!()
 }
 
diff --git a/src/eval/jit/mod.rs b/src/eval/jit/mod.rs
index bd198f8..ba6a330 100644
--- a/src/eval/jit/mod.rs
+++ b/src/eval/jit/mod.rs
@@ -7,11 +7,11 @@ use inkwell::context::Context;
 use inkwell::execution_engine::ExecutionEngine;
 use inkwell::module::Module;
 use inkwell::values::{
-    AnyValue, AsValueRef, BasicMetadataValueEnum, BasicValueEnum, IntValue, StructValue,
+    AnyValue, BasicMetadataValueEnum, FloatValue, IntValue, StructValue
 };
 
-use crate::env::VmEnv;
-use crate::ir::{Ir, UnOpKind};
+use crate::env::Env;
+use crate::ir::Ir;
 use crate::ty::internal::Value;
 
 mod compile;
@@ -60,10 +60,10 @@ impl From<JITValue> for Value {
         match value.tag {
             Int => Value::Int(unsafe { value.data.int }),
             Null => Value::Null,
-            /* Function => Value::Func(unsafe { Rc::from_raw(value.data.ptr as *const _) }),
-            Thunk => Value::Thunk(self::Thunk {
-                thunk: unsafe { Rc::from_raw(value.data.ptr as *const _) },
-            }), */
+            Function => Value::Func(unsafe { value.data.int as usize}),
+            Thunk => Value::Thunk(unsafe {
+                value.data.int as usize
+            }),
             _ => todo!("not implemented for {:?}", value.tag),
         }
     }
@@ -94,7 +94,7 @@ impl From<Value> for JITValue {
 }
 
 pub struct JITFunc<'ctx>(F, PhantomData<&'ctx mut ()>);
-type F = unsafe extern "C" fn(*const VmEnv) -> JITValue;
+type F = unsafe extern "C" fn(*const Env) -> JITValue;
 
 impl From<F> for JITFunc<'_> {
     fn from(value: F) -> Self {
@@ -144,6 +144,60 @@ impl<'ctx> JITContext<'ctx> {
         todo!()
     }
 
+    pub fn get_float(&self, val: StructValue<'ctx>) -> FloatValue<'ctx> {
+        let alloca = self
+            .builder
+            .build_alloca(self.helpers.int_type, "get_value_alloca")
+            .unwrap();
+        self.builder.build_store(alloca, val).unwrap();
+        self.builder
+            .build_load(
+                self.helpers.float_type,
+                self.builder
+                    .build_struct_gep(self.helpers.value_type, alloca, 1, "get_value_gep")
+                    .unwrap(),
+                "get_value",
+            )
+            .unwrap()
+            .into_float_value()
+    }
+
+    pub fn get_int(&self, val: StructValue<'ctx>) -> IntValue<'ctx> {
+        let alloca = self
+            .builder
+            .build_alloca(self.helpers.int_type, "get_value_alloca")
+            .unwrap();
+        self.builder.build_store(alloca, val).unwrap();
+        self.builder
+            .build_load(
+                self.helpers.int_type,
+                self.builder
+                    .build_struct_gep(self.helpers.value_type, alloca, 1, "get_value_gep")
+                    .unwrap(),
+                "get_value",
+            )
+            .unwrap()
+            .into_int_value()
+    }
+
+    pub fn get_bool(&self, val: StructValue<'ctx>) -> IntValue<'ctx> {
+        let alloca = self
+            .builder
+            .build_alloca(self.helpers.bool_type, "get_value_alloca")
+            .unwrap();
+        self.builder.build_store(alloca, val).unwrap();
+        self.builder
+            .build_load(
+                self.helpers.bool_type,
+                self.builder
+                    .build_struct_gep(self.helpers.value_type, alloca, 1, "get_value_gep")
+                    .unwrap(),
+                "get_value",
+            )
+            .unwrap()
+            .into_int_value()
+    }
+
     pub fn get_tag(&self, val: StructValue<'ctx>) -> IntValue<'ctx> {
         let alloca = self
             .builder
@@ -152,9 +206,9 @@ impl<'ctx> JITContext<'ctx> {
         self.builder.build_store(alloca, val).unwrap();
         self.builder
             .build_load(
-                self.context.bool_type(),
+                self.helpers.int_type,
                 self.builder
-                    .build_struct_gep(self.helpers.value_type, alloca, 1, "get_tag_gep")
+                    .build_struct_gep(self.helpers.value_type, alloca, 0, "get_tag_gep")
                     .unwrap(),
                 "get_tag",
             )
diff --git a/src/eval/mod.rs b/src/eval/mod.rs
index be8bdb5..8bfb813 100644
--- a/src/eval/mod.rs
+++ b/src/eval/mod.rs
@@ -1,30 +1,30 @@
 use ecow::EcoVec;
 
 use crate::engine::Engine;
-use crate::env::VmEnv;
+use crate::env::Env;
 use crate::error::{Error, Result};
 use crate::ir::{self, DynAttr};
 use crate::ty::common::Const;
-use crate::ty::internal::{AttrSet, EnvRef, List, ThunkRef, Value};
+use crate::ty::internal::{AttrSet, List, Value};
 use crate::ty::public::Symbol;
 
 pub mod jit;
 
 pub trait Evaluate {
-    fn eval(self, engine: &mut Engine, env: &mut VmEnv) -> Result<Value>;
+    fn eval(&self, engine: &mut Engine, env: &mut Env) -> Result<Value>;
 }
 
 impl Evaluate for ir::Attrs {
-    fn eval(self, engine: &mut Engine, env: &mut VmEnv) -> Result<Value> {
+    fn eval(&self, engine: &mut Engine, env: &mut Env) -> Result<Value> {
         let mut attrs = AttrSet::new(
             self.stcs
-                .into_iter()
-                .map(|(k, v)| Ok((k, v.eval(engine, env)?)))
+                .iter()
+                .map(|(k, v)| Ok((k.clone(), v.eval(engine, env)?)))
                 .collect::<Result<_>>()?,
         );
-        for DynAttr(k, v) in self.dyns {
+        for DynAttr(k, v) in self.dyns.iter() {
             let mut k = k.eval(engine, env)?;
-            k.force(engine, env)?.coerce_to_string();
+            k.coerce_to_string();
             attrs.push_attr(k.unwrap_string(), v.eval(engine, env)?);
         }
         Value::AttrSet(attrs.into()).ok()
@@ -32,10 +32,10 @@ impl Evaluate for ir::Attrs {
 }
 
 impl Evaluate for ir::List {
-    fn eval(self, engine: &mut Engine, env: &mut VmEnv) -> Result<Value> {
+    fn eval(&self, engine: &mut Engine, env: &mut Env) -> Result<Value> {
         Value::List(List::from(
             self.items
-                .into_iter()
+                .iter()
                 .map(|val| val.eval(engine, env))
                 .collect::<Result<EcoVec<_>>>()?,
         ))
@@ -44,16 +44,16 @@ impl Evaluate for ir::List {
 }
 
 impl Evaluate for ir::HasAttr {
-    fn eval(self, engine: &mut Engine, env: &mut VmEnv) -> Result<Value> {
+    fn eval(&self, engine: &mut Engine, env: &mut Env) -> Result<Value> {
         use ir::Attr::*;
         let mut val = self.lhs.eval(engine, env)?;
-        val.has_attr(self.rhs.into_iter().map(|attr| {
+        val.has_attr(self.rhs.iter().map(|attr| {
             Ok(match attr {
-                Str(ident) => ident,
+                Str(ident) => ident.clone(),
                 Strs(expr) => expr.eval(engine, env)?.unwrap_string(),
                 Dynamic(expr) => {
                     let mut val = expr.eval(engine, env)?;
-                    val.force(engine, env)?.coerce_to_string();
+                    val.coerce_to_string();
                     val.unwrap_string()
                 }
             })
@@ -63,12 +63,10 @@ impl Evaluate for ir::HasAttr {
 }
 
 impl Evaluate for ir::BinOp {
-    fn eval(self, engine: &mut Engine, env: &mut VmEnv) -> Result<Value> {
+    fn eval(&self, engine: &mut Engine, env: &mut Env) -> Result<Value> {
         use ir::BinOpKind::*;
         let mut lhs = self.lhs.eval(engine, env)?;
         let mut rhs = self.rhs.eval(engine, env)?;
-        lhs.force(engine, env)?;
-        rhs.force(engine, env)?;
         match self.kind {
             Add => lhs.add(rhs),
             Sub => {
@@ -115,10 +113,9 @@ impl Evaluate for ir::BinOp {
 }
 
 impl Evaluate for ir::UnOp {
-    fn eval(self, engine: &mut Engine, env: &mut VmEnv) -> Result<Value> {
+    fn eval(&self, engine: &mut Engine, env: &mut Env) -> Result<Value> {
         use ir::UnOpKind::*;
         let mut rhs = self.rhs.eval(engine, env)?;
-        rhs.force(engine, env)?;
         match self.kind {
             Neg => rhs.neg(),
             Not => rhs.not(),
@@ -128,19 +125,19 @@ impl Evaluate for ir::UnOp {
 }
 
 impl Evaluate for ir::Select {
-    fn eval(self, engine: &mut Engine, env: &mut VmEnv) -> Result<Value> {
+    fn eval(&self, engine: &mut Engine, env: &mut Env) -> Result<Value> {
         use ir::Attr::*;
         let mut val = self.expr.eval(engine, env)?;
-        if let Some(default) = self.default {
+        if let Some(default) = &self.default {
             let default = default.eval(engine, env)?;
-            val.force(engine, env)?.select_with_default(
-                self.attrpath.into_iter().map(|attr| {
+            val.select_with_default(
+                self.attrpath.iter().map(|attr| {
                     Ok(match attr {
-                        Str(ident) => ident,
+                        Str(ident) => ident.clone(),
                         Strs(expr) => expr.eval(engine, env)?.unwrap_string(),
                         Dynamic(expr) => {
                             let mut val = expr.eval(engine, env)?;
-                            val.force(engine, env)?.coerce_to_string();
+                            val.coerce_to_string();
                             val.unwrap_string()
                         }
                     })
@@ -148,14 +145,14 @@ impl Evaluate for ir::Select {
                 default,
             )?;
         } else {
-            val.force(engine, env)?
-                .select(self.attrpath.into_iter().map(|attr| {
+            val
+                .select(self.attrpath.iter().map(|attr| {
                     Ok(match attr {
-                        Str(ident) => ident,
+                        Str(ident) => ident.clone(),
                         Strs(expr) => expr.eval(engine, env)?.unwrap_string(),
                         Dynamic(expr) => {
                             let mut val = expr.eval(engine, env)?;
-                            val.force(engine, env)?.coerce_to_string();
+                            val.coerce_to_string();
                             val.unwrap_string()
                         }
                     })
@@ -166,7 +163,7 @@ impl Evaluate for ir::Select {
 }
 
 impl Evaluate for ir::If {
-    fn eval(self, engine: &mut Engine, env: &mut VmEnv) -> Result<Value> {
+    fn eval(&self, engine: &mut Engine, env: &mut Env) -> Result<Value> {
         // TODO: Error Handling
         let cond = self.cond.eval(engine, env)?.unwrap_bool();
         if cond {
@@ -178,19 +175,18 @@ impl Evaluate for ir::If {
 }
 
 impl Evaluate for ir::LoadFunc {
-    fn eval(self, engine: &mut Engine, env: &mut VmEnv) -> Result<Value> {
+    fn eval(&self, engine: &mut Engine, env: &mut Env) -> Result<Value> {
         let idx = engine.func_offset + self.idx;
         Value::Func(idx).ok()
     }
 }
 
 impl Evaluate for ir::Call {
-    fn eval(self, engine: &mut Engine, env: &mut VmEnv) -> Result<Value> {
+    fn eval(&self, engine: &mut Engine, env: &mut Env) -> Result<Value> {
         let mut func = self.func.eval(engine, env)?;
-        func.force(engine, env)?;
         func.call(
             self.args
-                .into_iter()
+                .iter()
                 .map(|arg| arg.eval(engine, env))
                 .collect::<Result<_>>()?,
             engine,
@@ -205,13 +201,13 @@ impl Evaluate for ir::Call {
 }
 
 impl Evaluate for ir::Let {
-    fn eval(self, engine: &mut Engine, env: &mut VmEnv) -> Result<Value> {
+    fn eval(&self, engine: &mut Engine, env: &mut Env) -> Result<Value> {
         unreachable!()
     }
 }
 
 impl Evaluate for ir::With {
-    fn eval(self, engine: &mut Engine, env: &mut VmEnv) -> Result<Value> {
+    fn eval(&self, engine: &mut Engine, env: &mut Env) -> Result<Value> {
         let namespace = self.namespace.eval(engine, env)?;
         // TODO: Error Handling
         env.enter_with(namespace.unwrap_attr_set().into_inner());
@@ -222,19 +218,19 @@ impl Evaluate for ir::With {
 }
 
 impl Evaluate for ir::Assert {
-    fn eval(self, engine: &mut Engine, env: &mut VmEnv) -> Result<Value> {
+    fn eval(&self, engine: &mut Engine, env: &mut Env) -> Result<Value> {
         todo!()
     }
 }
 
 impl Evaluate for ir::ConcatStrings {
-    fn eval(self, engine: &mut Engine, env: &mut VmEnv) -> Result<Value> {
+    fn eval(&self, engine: &mut Engine, env: &mut Env) -> Result<Value> {
         let mut parts = self
             .parts
-            .into_iter()
+            .iter()
             .map(|part| {
                 let mut part = part.eval(engine, env)?;
-                part.force(engine, env)?.coerce_to_string();
+                part.coerce_to_string();
                 part.ok()
             })
             .collect::<Result<Vec<_>>>()?
@@ -250,13 +246,13 @@ impl Evaluate for ir::ConcatStrings {
 }
 
 impl Evaluate for ir::String {
-    fn eval(self, _: &mut Engine, _: &mut VmEnv) -> Result<Value> {
-        Value::String(self.val).ok()
+    fn eval(&self, _: &mut Engine, _: &mut Env) -> Result<Value> {
+        Value::String(self.val.clone()).ok()
     }
 }
 
 impl Evaluate for ir::Const {
-    fn eval(self, _: &mut Engine, _: &mut VmEnv) -> Result<Value> {
+    fn eval(&self, _: &mut Engine, _: &mut Env) -> Result<Value> {
         match self.val {
             Const::Null => Value::Null,
             Const::Int(x) => Value::Int(x),
@@ -268,33 +264,34 @@ impl Evaluate for ir::Const {
 }
 
 impl Evaluate for ir::Var {
-    fn eval(self, _: &mut Engine, env: &mut VmEnv) -> Result<Value> {
+    fn eval(&self, _: &mut Engine, env: &mut Env) -> Result<Value> {
         env.lookup_with(&self.sym).ok_or_else(|| {
-            Error::EvalError(format!("variable {} not found", Symbol::from(self.sym)))
+            Error::EvalError(format!("variable {} not found", Symbol::from(self.sym.clone())))
         })
     }
 }
 
 impl Evaluate for ir::Arg {
-    fn eval(self, _: &mut Engine, env: &mut VmEnv) -> Result<Value> {
+    fn eval(&self, _: &mut Engine, env: &mut Env) -> Result<Value> {
         env.lookup_arg(self.level).clone().ok()
     }
 }
 
 impl Evaluate for ir::LetVar {
-    fn eval(self, _: &mut Engine, env: &mut VmEnv) -> Result<Value> {
+    fn eval(&self, _: &mut Engine, env: &mut Env) -> Result<Value> {
         unreachable!()
     }
 }
 
 impl Evaluate for ir::Thunk {
-    fn eval(self, _: &mut Engine, _: &mut VmEnv) -> Result<Value> {
-        Value::Thunk(ThunkRef::new(self.idx)).ok()
+    fn eval(&self, engine: &mut Engine, env: &mut Env) -> Result<Value> {
+        env.lookup_cache(self.idx, |env| engine.eval_thunk(self.idx, env))
+        // Value::Thunk(self.idx).ok()
     }
 }
 
 impl Evaluate for ir::MaybeThunk {
-    fn eval(self, engine: &mut Engine, env: &mut VmEnv) -> Result<Value> {
+    fn eval(&self, engine: &mut Engine, env: &mut Env) -> Result<Value> {
         match self {
             ir::MaybeThunk::Const(cnst) => cnst.eval(engine, env),
             ir::MaybeThunk::String(string) => string.eval(engine, env),
@@ -304,7 +301,7 @@ impl Evaluate for ir::MaybeThunk {
 }
 
 impl Evaluate for ir::Path {
-    fn eval(self, engine: &mut Engine, env: &mut VmEnv) -> Result<Value> {
+    fn eval(&self, engine: &mut Engine, env: &mut Env) -> Result<Value> {
         todo!()
     }
 }
diff --git a/src/ir/ctx.rs b/src/ir/ctx.rs
index da40f17..3794ba3 100644
--- a/src/ir/ctx.rs
+++ b/src/ir/ctx.rs
@@ -9,7 +9,7 @@ use crate::{
 
 use super::{Dep, Func, Ir, LoadFunc, MaybeThunk, SccAnalyzer, SccNode, Thunk};
 
-#[derive(Clone, Copy, Unwrap)]
+#[derive(Clone, Copy, Unwrap, Debug)]
 pub enum Index {
     Thunk(usize),
     Func(usize),
@@ -169,9 +169,11 @@ impl DowngradeContext {
     }
 
     pub fn new_dep(&mut self, this: Index, dep: Dep) -> Result<()> {
+        #[cfg(debug_assertions)]
+        println!("{this:?} => {dep:?}");
         match this {
             Index::Thunk(idx) => {
-                if dep == Dep::Thunk(idx) {
+                if dep == Dep::Thunk(idx) && !matches!(self.thunks[idx].0, Ir::List(_)) {
                     return Err(Error::DowngradeError(
                         "infinite recursion encountered".into(),
                     ));
diff --git a/src/ir/mod.rs b/src/ir/mod.rs
index 377a81b..d5656a0 100644
--- a/src/ir/mod.rs
+++ b/src/ir/mod.rs
@@ -8,7 +8,7 @@ use rnix::ast::{self, Expr};
 
 use crate::builtins::ir_env;
 use crate::engine::Engine;
-use crate::env::VmEnv;
+use crate::env::Env as VmEnv;
 use crate::error::*;
 use crate::eval::Evaluate;
 use crate::eval::jit::{JITCompile, JITContext};
@@ -90,7 +90,7 @@ macro_rules! ir {
         }
 
         impl JITCompile for Ir {
-            fn compile<'ctx>(self, ctx: &JITContext<'ctx>, func: FunctionValue<'ctx>) -> StructValue<'ctx>{
+            fn compile<'ctx>(&self, ctx: &JITContext<'ctx>, func: FunctionValue<'ctx>) -> StructValue<'ctx>{
                 match self {
                     $(Ir::$ty(ir) => ir.compile(ctx, func),)*
                 }
@@ -98,7 +98,7 @@ macro_rules! ir {
         }
 
         impl Evaluate for Ir {
-            fn eval(self, engine: &mut Engine, env: &mut VmEnv) -> Result<Value> {
+            fn eval(&self, engine: &mut Engine, env: &mut VmEnv) -> Result<Value> {
                 match self {
                     $(Ir::$ty(ir) => ir.eval(engine, env),)*
                 }
@@ -1060,7 +1060,11 @@ impl Let {
         env: &Env<'a, 'env>,
     ) -> Result<Ir> {
         let map = self.bindings.clone();
-        let env = env.enter_let(&map);
+        let mut env = env.enter_let(&map);
+        self.bindings.into_iter().map(|(_, ir)| {
+            ir.resolve(self_idx, ctx, &mut env)?;
+            Ok(())
+        }).collect::<Result<()>>()?;
         self.expr.resolve(self_idx, ctx, &env)?.ok()
     }
 }
diff --git a/src/ir/scc.rs b/src/ir/scc.rs
index 90a17bc..c061300 100644
--- a/src/ir/scc.rs
+++ b/src/ir/scc.rs
@@ -18,6 +18,7 @@ pub enum Dep {
 #[derive(Default, Debug)]
 pub struct SccGraph {
     nodes: HashMap<usize, SccNode>,
+    root: usize,
 }
 
 impl SccGraph {
@@ -38,6 +39,7 @@ impl SccGraph {
                 },
             );
         }
+        graph.root = thunk_to_scc[&(ctx.thunks.len() - 1)];
 
         for (from_node_id, from_deps) in ctx.thunk_deps.iter().enumerate() {
             let from_scc_id = thunk_to_scc[&from_node_id];
@@ -58,28 +60,51 @@ impl SccGraph {
     }
 
     fn sorted(self) -> Vec<SccNode> {
-        let mut in_degrees: HashMap<usize, usize> = self.nodes.keys().map(|&id| (id, 0)).collect();
-        for node in self.nodes.values() {
-            in_degrees.insert(node.id, node.deps.len());
+        let mut reachable = HashSet::new();
+        let mut stack = vec![self.root];
+        reachable.insert(self.root);
+
+        while let Some(id) = stack.pop() {
+            if let Some(node) = self.nodes.get(&id) {
+                for &dep_id in &node.deps {
+                    if reachable.insert(dep_id) {
+                        stack.push(dep_id);
+                    }
+                }
+            }
         }
 
+        let mut in_degrees: HashMap<usize, usize> = HashMap::new();
         let mut reverse_adj: HashMap<usize, Vec<usize>> = HashMap::new();
-        for (node_id, node) in &self.nodes {
-            for &dep_id in &node.deps {
-                reverse_adj.entry(dep_id).or_default().push(*node_id);
+
+        for &id in &reachable {
+            in_degrees.insert(id, 0);
+        }
+
+        for &id in &reachable {
+            if let Some(node) = self.nodes.get(&id) {
+                for &dep_id in &node.deps {
+                    if reachable.contains(&dep_id) {
+                        reverse_adj.entry(dep_id).or_default().push(id);
+                        *in_degrees.get_mut(&id).unwrap() += 1;
+                    }
+                }
             }
         }
 
         let mut queue: std::collections::VecDeque<usize> = in_degrees
             .iter()
-            .filter_map(|(&id, &deg)| if deg == 0 { Some(id) } else { None })
+            .filter(|(_, deg)| **deg == 0)
+            .map(|(&id, _)| id)
             .collect();
 
         queue.make_contiguous().sort();
 
         let mut sorted_order = Vec::new();
         while let Some(u) = queue.pop_front() {
-            sorted_order.push(self.nodes[&u].clone());
+            if let Some(node) = self.nodes.get(&u) {
+                sorted_order.push(node.clone());
+            }
 
             if let Some(dependents) = reverse_adj.get(&u) {
                 for &v in dependents {
@@ -93,8 +118,8 @@ impl SccGraph {
             }
         }
 
-        if sorted_order.len() != self.nodes.len() {
-            panic!("Cycle detected in SCC graph, which is impossible!");
+        if sorted_order.len() != reachable.len() {
+            panic!("Cycle detected in the reachable part of SCC graph!");
         }
 
         sorted_order
diff --git a/src/ty/internal/func.rs b/src/ty/internal/func.rs
index ff64e1a..360f8d5 100644
--- a/src/ty/internal/func.rs
+++ b/src/ty/internal/func.rs
@@ -1,15 +1,15 @@
 use std::rc::Rc;
 
-use crate::env::VmEnv;
+use crate::env::Env;
 
 use crate::ir;
 pub struct Func<'gc> {
     pub func: &'gc ir::Func,
-    pub env: Rc<VmEnv>,
+    pub env: Rc<Env>,
 }
 
 impl<'gc> Func<'gc> {
-    pub fn new(func: &'gc ir::Func, env: Rc<VmEnv>) -> Self {
+    pub fn new(func: &'gc ir::Func, env: Rc<Env>) -> Self {
         Self { func, env }
     }
 }
diff --git a/src/ty/internal/list.rs b/src/ty/internal/list.rs
index 3a49f46..da02ea7 100644
--- a/src/ty/internal/list.rs
+++ b/src/ty/internal/list.rs
@@ -5,7 +5,7 @@ use ecow::EcoVec;
 use hashbrown::HashSet;
 
 use crate::engine::Engine;
-use crate::env::VmEnv;
+use crate::env::Env;
 use crate::ty::public as p;
 
 use super::Value;
diff --git a/src/ty/internal/mod.rs b/src/ty/internal/mod.rs
index 1ed3666..3351830 100644
--- a/src/ty/internal/mod.rs
+++ b/src/ty/internal/mod.rs
@@ -10,7 +10,7 @@ use super::common::*;
 use super::public as p;
 
 use crate::engine::Engine;
-use crate::env::{VmEnv, VmEnvWeak};
+use crate::env::{Env, VmEnvWeak};
 use crate::error::*;
 
 mod attrset;
@@ -23,45 +23,6 @@ pub use attrset::*;
 pub use list::List;
 pub use primop::*;
 
-#[derive(Clone)]
-pub enum EnvRef {
-    Strong(VmEnv),
-    Weak(VmEnvWeak),
-}
-
-#[derive(Clone, Debug)]
-pub struct ThunkRef {
-    pub idx: usize,
-    // pub env: Option<EnvRef>,
-}
-
-impl ThunkRef {
-    pub fn new(idx: usize) -> Self {
-        ThunkRef {
-            idx, /* env: None */
-        }
-    }
-    /*
-    pub fn capture(&mut self, env: EnvRef) {
-        let _ = self.env.insert(env);
-    }
-
-    pub fn upgrade(&mut self) {
-        replace_with_or_abort(&mut self.env, |env| {
-            env.map(|env| EnvRef::Strong(env.upgraded()))
-        });
-    } */
-}
-/*
-impl EnvRef {
-    pub fn upgraded(self) -> VmEnv {
-        match self {
-            EnvRef::Weak(weak) => weak.upgrade(),
-            EnvRef::Strong(strong) => strong,
-        }
-    }
-} */
-
 #[derive(IsVariant, Unwrap, Clone, Debug)]
 pub enum Value {
     Int(i64),
@@ -69,7 +30,7 @@ pub enum Value {
     Bool(bool),
     String(EcoString),
     Null,
-    Thunk(ThunkRef),
+    Thunk(usize),
     AttrSet(Rc<AttrSet>),
     List(List),
     Catchable(EcoString),
@@ -129,7 +90,7 @@ pub enum ValueAsRef<'v> {
     Bool(bool),
     String(&'v EcoString),
     Null,
-    Thunk(&'v ThunkRef),
+    Thunk(usize),
     AttrSet(&'v AttrSet),
     List(&'v List),
     Catchable(&'v str),
@@ -149,7 +110,7 @@ impl Value {
             Bool(x) => R::Bool(*x),
             String(x) => R::String(x),
             Null => R::Null,
-            Thunk(x) => R::Thunk(x),
+            Thunk(x) => R::Thunk(*x),
             AttrSet(x) => R::AttrSet(x),
             List(x) => R::List(x),
             Catchable(x) => R::Catchable(x),
@@ -192,7 +153,7 @@ impl Value {
         }
     }
 
-    pub fn call(&mut self, args: Vec<Self>, engine: &mut Engine, env: &mut VmEnv) -> Result<()> {
+    pub fn call(&mut self, args: Vec<Self>, engine: &mut Engine, env: &mut Env) -> Result<()> {
         use Value::*;
         for arg in args.iter() {
             if matches!(arg, Value::Catchable(_)) {
@@ -206,6 +167,7 @@ impl Value {
             PartialFunc(idx, old) => {
                 let idx = *idx;
                 let len = args.len() + old.len();
+                env.reserve_args(len);
                 env.enter_args(std::mem::take(old));
                 env.enter_cache_level(|env| {
                     let mut args = args.into_iter().peekable();
@@ -240,6 +202,7 @@ impl Value {
             &mut Func(idx) => {
                 let len = args.len();
                 let mut args = args.into_iter().peekable();
+                env.reserve_args(len);
                 env.enter_cache_level(|env| {
                     env.enter_arg(args.next().unwrap());
                     let mut ret = engine.eval_thunk(idx, env)?;
@@ -510,18 +473,9 @@ impl Value {
         self
     }
 
-    pub fn force(&mut self, engine: &mut Engine, env: &mut VmEnv) -> Result<&mut Self> {
-        if let Value::Thunk(thunk) = self {
-            unsafe {
-                let old = std::ptr::read(thunk);
-                match env.lookup_cache(old.idx, |env| engine.eval_thunk(old.idx, env)) {
-                    Ok(ok) => std::ptr::write(self, ok),
-                    Err(err) => {
-                        std::ptr::write(self, Self::Null);
-                        return Err(err);
-                    }
-                }
-            }
+    pub fn force(&mut self, engine: &mut Engine, env: &mut Env) -> Result<&mut Self> {
+        if let &mut Value::Thunk(idx) = self {
+            *self = env.lookup_cache(idx, |env| engine.eval_thunk(idx, env))?
         }
         Ok(self)
     }