Refactor closure instantiation and inlining

This commit makes several changes related to how closures are handled:

- **Dumper:** Removes redundant introspection of closure ASTs, as this
  is no longer relevant.
- **Optimizer:** Updates `try_inline` to accept `ExecNode` for
  parameters and adds a check to ensure the `function_node` is a
  `Lambda` before attempting inlining.
- **Environment:** Simplifies closure creation by passing an `ExecNode`
  for parameters and ensuring the correct `stack_size` is used.
- **VM:** Adjusts `Closure` to store an `ExecNode` for parameters and
  updates `VM::unpack` to accept an `ExecNode`.

src/ast/compiler/dumper.rs

@@ -1,6 +1,4 @@
 use crate::ast::compiler::bound_nodes::{BoundKind, Node};
-use crate::ast::types::Value;
-use crate::ast::vm::Closure;
 use std::fmt::Debug;
 
 /// Human-readable AST dumper for the bound AST.
@@ -38,28 +36,6 @@ impl Dumper {
             BoundKind::Nop => self.log("Nop", node),
             BoundKind::Constant(v) => {
                 self.log(&format!("Constant: {}", v), node);
-                // Introspect Closure AST if possible
-                if let Value::Object(obj) = v
-                    && let Some(closure) = obj.as_any().downcast_ref::<Closure>()
-                {
-                    self.indent += 1;
-                    self.write_indent();
-                    self.output.push_str("--- Specialized Body ---\n");
-                    // We need to cast the inner TypedNode to the generic T required by visit.
-                    // Since Dumper is generic over T, but Closure stores TypedNode (where T = StaticType),
-                    // we can only fully dump if T is StaticType.
-                    // However, we can hack it by creating a new Dumper for the inner AST string.
-
-                    // We can't call self.visit because types mismatch if T != StaticType.
-                    // So we just recursively dump to string and append.
-                    let inner_dump = Dumper::dump(&closure.function_node);
-                    for line in inner_dump.lines() {
-                        self.write_indent();
-                        self.output.push_str(line);
-                        self.output.push('\n');
-                    }
-                    self.indent -= 1;
-                }
             }
             BoundKind::Get { addr, name } => {
                 self.log(&format!("Get: {} ({:?})", name.name, addr), node)

src/ast/compiler/optimizer/engine.rs

@@ -334,8 +334,9 @@ impl Optimizer {
                         }
 
                         path.inlining_depth += 1;
+                        if let BoundKind::Lambda { params, .. } = &closure.function_node.kind {
                             let collapsed = self.try_inline(
-                            &closure.parameter_node,
+                                params,
                                 &arg_nodes,
                                 &closure.function_node,
                                 sub,
@@ -348,6 +349,10 @@ impl Optimizer {
                             if let Some(res) = collapsed {
                                 return res;
                             }
+                        } else {
+                            path.inlining_depth -= 1;
+                            path.exit_lambda(&closure.function_node.identity);
+                        }
                     }
 
                     if let Some(folded) = folder.try_fold_pure(&callee_opt, &arg_nodes) {

src/ast/environment.rs

@@ -666,14 +666,13 @@ impl Environment {
         } = &node.kind
             && upvalues.is_empty()
         {
-            let stack_size = node.ty.stack_size;
             let closure = Rc::new(crate::ast::vm::Closure::new(
-                params.ty.original.clone(),
+                params.clone(),
                 body.ty.original.clone(),
                 body.clone(),
-                vec![],
+                Vec::new(),
                 *positional_count,
-                stack_size,
+                node.ty.stack_size,
             ));
             let closure_obj: Rc<dyn crate::ast::types::Object> = closure;
 

src/ast/vm.rs

@@ -1,6 +1,5 @@
 use crate::ast::compiler::bound_nodes::{Address, AnalyzedNode, BoundKind};
 use crate::ast::compiler::lowering::ExecNode;
-use crate::ast::compiler::bound_nodes::Node;
 use crate::ast::types::{Object, Value};
 use std::any::Any;
 use std::cell::RefCell;
@@ -8,8 +7,8 @@ use std::rc::Rc;
 
 #[derive(Debug, Clone)]
 pub struct Closure {
-    /// The analyzed parameter pattern.
+    /// The executable parameter pattern.
-    pub parameter_node: Rc<AnalyzedNode>,
+    pub parameter_node: Rc<ExecNode>,
     /// The analyzed body (before TCO).
     pub function_node: Rc<AnalyzedNode>,
     /// The executable node (after TCO).
@@ -23,7 +22,7 @@ pub struct Closure {
 impl Closure {
     #[inline]
     pub fn new(
-        params: Rc<AnalyzedNode>,
+        params: Rc<ExecNode>,
         body: Rc<AnalyzedNode>,
         exec: Rc<ExecNode>,
         upvalues: Vec<Rc<RefCell<Value>>>,
@@ -512,7 +511,7 @@ impl VM {
                 }
                 let stack_size = node.ty.stack_size;
                 let closure = Closure::new(
-                    params.ty.original.clone(),
+                    params.clone(),
                     body.ty.original.clone(),
                     body.clone(),
                     captured,
@@ -1026,9 +1025,9 @@ impl VM {
         }
     }
 
-    fn unpack<T>(
+    fn unpack(
         &mut self,
-        pattern: &Node<T>,
+        pattern: &ExecNode,
         values: &[Value],
         offset: &mut usize,
     ) -> Result<(), String> {