Refactor Destructure to handle assignments

Renames `DefDestructure` to `Destructure` to better reflect its use in
both definitions and assignments.
Introduces `bind_assign_pattern` to handle assignment destructuring in
the binder.
Adds `test_assign_destructuring` to verify assignment destructuring
functionality.

src/ast/compiler/analyzer.rs

@@ -178,11 +178,11 @@ impl<'a> Analyzer<'a> {
                 )
             }
 
-            BoundKind::DefDestructure { pattern, value } => {
+            BoundKind::Destructure { pattern, value } => {
                 let pat_m = self.visit(Rc::new((**pattern).clone()));
                 let val_m = self.visit(Rc::new((**value).clone()));
                 (
-                    BoundKind::DefDestructure {
+                    BoundKind::Destructure {
                         pattern: Box::new(pat_m),
                         value: Box::new(val_m),
                     },

src/ast/compiler/binder.rs

@@ -209,7 +209,7 @@ impl Binder {
 
                     Ok(self.make_node(
                         node.identity.clone(),
-                        BoundKind::DefDestructure {
+                        BoundKind::Destructure {
                             pattern: Box::new(target_node),
                             value: Box::new(val_node),
                         },
@@ -230,7 +230,14 @@ impl Binder {
                         },
                     ))
                 } else {
-                    Err("Assignment target must be an identifier".to_string())
+                    let target_node = self.bind_assign_pattern(target)?;
+                    Ok(self.make_node(
+                        node.identity.clone(),
+                        BoundKind::Destructure {
+                            pattern: Box::new(target_node),
+                            value: Box::new(val_node),
+                        },
+                    ))
                 }
             }
 
@@ -456,6 +463,34 @@ impl Binder {
         }
     }
 
+    fn bind_assign_pattern(&mut self, node: &Node<UntypedKind>) -> Result<BoundNode, String> {
+        match &node.kind {
+            UntypedKind::Identifier(sym) => {
+                let addr = self.resolve_variable(sym)?;
+                Ok(self.make_node(
+                    node.identity.clone(),
+                    BoundKind::Set {
+                        addr,
+                        value: Box::new(self.make_node(node.identity.clone(), BoundKind::Nop)),
+                    },
+                ))
+            }
+            UntypedKind::Tuple { elements } => {
+                let mut bound_elems = Vec::new();
+                for e in elements {
+                    bound_elems.push(self.bind_assign_pattern(e)?);
+                }
+                Ok(self.make_node(
+                    node.identity.clone(),
+                    BoundKind::Tuple {
+                        elements: bound_elems,
+                    },
+                ))
+            }
+            _ => Err(format!("Invalid node in assignment pattern: {:?}", node.kind)),
+        }
+    }
+
     fn make_node(&self, identity: Identity, kind: BoundKind<()>) -> BoundNode {
         Node {
             identity,

src/ast/compiler/bound_nodes.rs

@@ -82,8 +82,8 @@ pub enum BoundKind<T = ()> {
         value: Box<BoundNode<T>>,
     },
 
-    /// A destructuring definition (can be local or global depending on the pattern)
-    DefDestructure {
+    /// A destructuring operation (can be a definition or an assignment depending on the pattern)
+    Destructure {
         pattern: Box<BoundNode<T>>,
         value: Box<BoundNode<T>>,
     },
@@ -194,11 +194,11 @@ where
                 },
             ) => na == nb && ga == gb && va == vb,
             (
-                BoundKind::DefDestructure {
+                BoundKind::Destructure {
                     pattern: pa,
                     value: va,
                 },
-                BoundKind::DefDestructure {
+                BoundKind::Destructure {
                     pattern: pb,
                     value: vb,
                 },
@@ -265,7 +265,7 @@ impl<T> BoundKind<T> {
             BoundKind::DefGlobal {
                 name, global_index, ..
             } => format!("DEF_GLOBAL({}, Idx:{})", name.name, global_index),
-            BoundKind::DefDestructure { .. } => "DEF_DESTRUCTURE".to_string(),
+            BoundKind::Destructure { .. } => "DESTRUCTURE".to_string(),
             BoundKind::Lambda {
                 params, upvalues, ..
             } => {

src/ast/compiler/dumper.rs

@@ -120,8 +120,8 @@ impl Dumper {
                 self.indent -= 1;
             }
 
-            BoundKind::DefDestructure { pattern, value } => {
-                self.log("DefDestructure", node);
+            BoundKind::Destructure { pattern, value } => {
+                self.log("Destructure", node);
                 self.indent += 1;
                 self.write_indent();
                 self.output.push_str("Pattern:\n");

src/ast/compiler/optimizer.rs

@@ -95,6 +95,34 @@ impl Optimizer {
         current
     }
 
+    fn collect_pattern_usage(&self, node: &AnalyzedNode, info: &mut UsageInfo) {
+        match &node.kind {
+            BoundKind::Parameter { slot, .. } => {
+                info.assigned_locals.insert(*slot);
+            }
+            BoundKind::DefGlobal { global_index, .. } => {
+                info.assigned_globals.insert(*global_index);
+            }
+            BoundKind::Set { addr, .. } => {
+                match addr {
+                    Address::Local(slot) => {
+                        info.assigned_locals.insert(*slot);
+                    }
+                    Address::Global(idx) => {
+                        info.assigned_globals.insert(*idx);
+                    }
+                    _ => {}
+                }
+            }
+            BoundKind::Tuple { elements } => {
+                for el in elements {
+                    self.collect_pattern_usage(el, info);
+                }
+            }
+            _ => {}
+        }
+    }
+
     fn visit_node(
         &self,
         node: AnalyzedNode,
@@ -561,6 +589,31 @@ impl Optimizer {
                 )
             }
 
+            BoundKind::Destructure {
+                ref pattern,
+                ref value,
+            } => {
+                let val_opt = Box::new(self.visit_node((**value).clone(), sub, path));
+                let pat_opt = Box::new(self.visit_node((**pattern).clone(), sub, path));
+
+                let mut info = UsageInfo::default();
+                self.collect_pattern_usage(&pat_opt, &mut info);
+                for slot in info.assigned_locals {
+                    sub.locals.remove(&slot);
+                }
+                for idx in info.assigned_globals {
+                    sub.globals.remove(&idx);
+                }
+
+                (
+                    BoundKind::Destructure {
+                        pattern: pat_opt,
+                        value: val_opt,
+                    },
+                    node.ty.clone(),
+                )
+            }
+
             BoundKind::Tuple { elements } => {
                 let elements = elements
                     .into_iter()
@@ -808,6 +861,10 @@ impl Optimizer {
 
     fn collect_usage(&self, node: &AnalyzedNode, info: &mut UsageInfo) {
         match &node.kind {
+            BoundKind::Destructure { pattern, value } => {
+                self.collect_pattern_usage(pattern, info);
+                self.collect_usage(value, info);
+            }
             BoundKind::Constant(v) => {
                 if let Value::Object(obj) = v
                     && let Some(closure) = obj.as_any().downcast_ref::<Closure>()

src/ast/compiler/tco.rs

@@ -118,7 +118,7 @@ impl TCO {
                 global_index: *global_index,
                 value: Box::new(Self::transform(Rc::new((**value).clone()), false)),
             },
-            BoundKind::DefDestructure { pattern, value } => BoundKind::DefDestructure {
+            BoundKind::Destructure { pattern, value } => BoundKind::Destructure {
                 pattern: Box::new(Self::transform(Rc::new((**pattern).clone()), false)),
                 value: Box::new(Self::transform(Rc::new((**value).clone()), false)),
             },

src/ast/compiler/type_checker.rs

@@ -163,6 +163,23 @@ impl TypeChecker {
                     specialized_ty.clone(),
                 )
             }
+            BoundKind::Set { addr, value: _value } => {
+                // In an assignment pattern, 'value' is just a Nop placeholder from the Binder.
+                // We update the type of the address (if it's a local or global) to match the specialized type.
+                // Note: For now, we assume assignments are compatible if types were already inferred,
+                // or we could add a check here against existing type.
+                (
+                    BoundKind::Set {
+                        addr,
+                        value: Box::new(Node {
+                            identity: node.identity.clone(),
+                            kind: BoundKind::Nop,
+                            ty: specialized_ty.clone(),
+                        }),
+                    },
+                    specialized_ty.clone(),
+                )
+            }
             BoundKind::Tuple { elements } => {
                 let mut typed_elements = Vec::new();
                 let mut elem_types = Vec::new();
@@ -282,12 +299,12 @@ impl TypeChecker {
                 )
             }
 
-            BoundKind::DefDestructure { pattern, value } => {
+            BoundKind::Destructure { pattern, value } => {
                 let val_typed = self.check_node(*value, ctx)?;
                 let pat_typed = self.check_params(*pattern, &val_typed.ty, ctx)?;
                 let ty = val_typed.ty.clone();
                 (
-                    BoundKind::DefDestructure {
+                    BoundKind::Destructure {
                         pattern: Box::new(pat_typed),
                         value: Box::new(val_typed),
                     },