feat: Add lambda collection and specialization

Introduces `LambdaCollector` to gather lambda functions and populate the
function registry. This enables the `Specializer` to work with
user-defined functions.

The `Environment` struct is updated to manage the `function_registry`
and `monomorph_cache`, which are essential for the specialization
process.

The `link` method in `Environment` now incorporates lambda collection
and node specialization before applying TCO optimization. This ensures
that lambdas are properly processed and specialized for potential
performance gains.

The `Specializer`'s `new` constructor has been modified to accept and
initialize the `MonoCache` through an `Rc<RefCell<MonoCache>>`. This
allows the cache to be shared across different specialized functions.

Also includes minor refactoring and type adjustments in `specializer.rs`
for better clarity and consistency.

src/ast/environment.rs

@@ -9,22 +9,44 @@ use crate::ast::compiler::{TypedNode, TypeChecker};
 use crate::ast::vm::{VM, TracingObserver};
 
 use crate::ast::compiler::tco::TCO;
+use crate::ast::compiler::lambda_collector::LambdaCollector;
 use crate::ast::compiler::dumper::Dumper;
 use crate::ast::compiler::macros::{MacroExpander, MacroRegistry, MacroEvaluator};
+use crate::ast::compiler::specializer::{Specializer, MonoCache, FunctionRegistry};
 use crate::ast::rtl;
+use crate::ast::rtl::intrinsics;
+use crate::ast::compiler::bound_nodes::{BoundKind, Address};
 
 pub struct Environment {
     pub global_names: Rc<RefCell<HashMap<Symbol, u32>>>,
     pub global_types: Rc<RefCell<HashMap<u32, StaticType>>>,
     pub global_values: Rc<RefCell<Vec<Value>>>,
+    pub function_registry: Rc<RefCell<HashMap<u32, TypedNode>>>,
+    pub monomorph_cache: Rc<RefCell<MonoCache>>,
     pub debug_mode: bool,
 }
 
+struct EnvFunctionRegistry {
+    registry: Rc<RefCell<HashMap<u32, TypedNode>>>,
+}
+
+impl FunctionRegistry for EnvFunctionRegistry {
+    fn resolve(&self, addr: Address) -> Option<TypedNode> {
+        if let Address::Global(idx) = addr {
+            self.registry.borrow().get(&idx).cloned()
+        } else {
+            None
+        }
+    }
+}
+
+
 /// Evaluator used during macro expansion to allow compile-time logic.
 struct RuntimeMacroEvaluator {
     global_names: Rc<RefCell<HashMap<Symbol, u32>>>,
     global_types: Rc<RefCell<HashMap<u32, StaticType>>>,
     global_values: Rc<RefCell<Vec<Value>>>,
+    function_registry: Rc<RefCell<HashMap<u32, TypedNode>>>,
 }
 
 impl MacroEvaluator for RuntimeMacroEvaluator {
@@ -58,6 +80,8 @@ impl Environment {
             global_names: Rc::new(RefCell::new(HashMap::new())),
             global_types: Rc::new(RefCell::new(HashMap::new())),
             global_values: Rc::new(RefCell::new(Vec::new())),
+            function_registry: Rc::new(RefCell::new(HashMap::new())),
+            monomorph_cache: Rc::new(RefCell::new(HashMap::new())),
             debug_mode: false,
         };
         env.register_stdlib();
@@ -73,6 +97,7 @@ impl Environment {
             global_names: self.global_names.clone(),
             global_types: self.global_types.clone(),
             global_values: self.global_values.clone(),
+            function_registry: self.function_registry.clone(),
         };
         MacroExpander::new(MacroRegistry::new(), evaluator)
     }
@@ -136,7 +161,83 @@ impl Environment {
 
     /// Backend: Optimization (TCO, etc.)
     pub fn link(&self, node: TypedNode) -> TypedNode {
-        TCO::optimize(node)
+        // 1. Collect Lambdas (Populate the registry for the specializer)
+        LambdaCollector::collect(&node, &mut self.function_registry.borrow_mut());
+
+        // 2. Specialize
+        let specialized = self.specialize_node(node);
+        // let specialized = node;
+
+        // 3. Optimize
+        TCO::optimize(specialized)
+    }
+
+    fn specialize_node(&self, node: TypedNode) -> TypedNode {
+        let registry = Rc::new(EnvFunctionRegistry {
+            registry: self.function_registry.clone(),
+        });
+        
+        let rtl_lookup = Rc::new(|name: &str, args: &[StaticType]| intrinsics::lookup(name, args));
+        
+        // We need to construct a compiler callback that can recursively specialize and compile.
+        // To avoid complex self-capturing, we reconstruct the environment context needed.
+        let func_reg = self.function_registry.clone();
+        let mono_cache = self.monomorph_cache.clone();
+        let global_values = self.global_values.clone(); // Needed for VM/Closure creation
+        
+        let compiler = Rc::new(move |func_node: TypedNode, _arg_types: &[StaticType]| -> Result<(Value, StaticType), String> {
+            // 1. Specialize the body (Recursive)
+            // We recreate the specializer context here. 
+            // Note: This creates a new Specializer for each recursion, but they SHARE the 'mono_cache'.
+            let sub_registry = Rc::new(EnvFunctionRegistry { registry: func_reg.clone() });
+            let sub_rtl_lookup = Rc::new(|name: &str, args: &[StaticType]| intrinsics::lookup(name, args));
+            
+            // Note: We are passing 'None' as compiler to the inner specializer for now to prevent infinite recursion on cycles.
+            // A robust implementation would handle the recursion cycle or use a shared compiler reference.
+            // For 'tak', the recursion is handled by the cache or dynamic fallback.
+            let sub_specializer = Specializer::new(
+                Some(sub_registry),
+                None, // recursive compilation limit (depth 1) for safety
+                Some(sub_rtl_lookup),
+                Some(mono_cache.clone())
+            );
+            
+            let specialized_ast = sub_specializer.specialize(func_node);
+            
+            // 2. Optimize (TCO)
+            let optimized_ast = TCO::optimize(specialized_ast);
+            
+            // 3. Compile to Closure (VM)
+            // We run the VM once to evaluate the Lambda definition, producing a closure Value.
+            let mut vm = VM::new(global_values.clone());
+            
+            let compiled_val = match vm.run(&optimized_ast) {
+                Ok(v) => v,
+                Err(e) => return Err(format!("VM Error during specialization: {}", e)),
+            };
+
+            // We need the return type.
+            // For a Lambda, the type is stored in the node.
+            // But we need the return type of the FUNCTION (e.g. Int), not the type of the Lambda node (Method).
+            // Actually, Specializer expects (Value, ReturnType).
+            // If the specialized function returns Int, we return Int.
+            let ret_type = if let BoundKind::Lambda { body, .. } = &optimized_ast.kind {
+                body.ty.clone()
+            } else {
+                StaticType::Any
+            };
+
+            Ok((compiled_val, ret_type))
+        });
+        
+        let specializer = Specializer::new(
+            Some(registry),
+            Some(compiler),
+            Some(rtl_lookup),
+            Some(self.monomorph_cache.clone()),
+        );
+        
+        specializer.specialize(node)
     }
 
     /// Runtime: Execute the linked AST in the VM