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

@@ -334,19 +334,24 @@ impl Optimizer {
                         }
 
                         path.inlining_depth += 1;
-                        let collapsed = self.try_inline(
-                            &closure.parameter_node,
-                            &arg_nodes,
-                            &closure.function_node,
-                            sub,
-                            path,
-                            Some(closure_sub),
-                        );
-                        path.inlining_depth -= 1;
-                        path.exit_lambda(&closure.function_node.identity);
+                        if let BoundKind::Lambda { params, .. } = &closure.function_node.kind {
+                            let collapsed = self.try_inline(
+                                params,
+                                &arg_nodes,
+                                &closure.function_node,
+                                sub,
+                                path,
+                                Some(closure_sub),
+                            );
+                            path.inlining_depth -= 1;
+                            path.exit_lambda(&closure.function_node.identity);
 
-                        if let Some(res) = collapsed {
-                            return res;
+                            if let Some(res) = collapsed {
+                                return res;
+                            }
+                        } else {
+                            path.inlining_depth -= 1;
+                            path.exit_lambda(&closure.function_node.identity);
                         }
                     }