feat: Implement AST binder and VM

Adds a new `Binder` struct that traverses the AST and resolves variable
references to concrete `Address` types (Local, Upvalue, Global). This
information is crucial for the Virtual Machine's execution phase.

Introduces the `BoundKind` enum to represent the AST after binding.

The `VM` is updated to handle `BoundKind` nodes and execute the bound
AST.
It now manages a call stack, local variables, and closures for function
calls and upvalue capturing.

The `Environment` struct is enhanced to manage global variables and
provide
a unified interface for parsing, binding, and executing scripts. It also
includes basic standard library functions.

src/ast/compiler/binder.rs

@@ -0,0 +1,219 @@
+use std::collections::HashMap;
+use std::sync::{Arc, Mutex};
+use crate::ast::nodes::{Node, UntypedKind};
+use crate::ast::compiler::bound_nodes::{BoundKind, Address};
+use crate::ast::types::{Value, Identity};
+
+#[derive(Debug, Clone)]
+struct CompilerScope {
+    locals: HashMap<String, u32>,
+    slot_count: u32,
+}
+
+impl CompilerScope {
+    fn new() -> Self {
+        Self {
+            locals: HashMap::new(),
+            slot_count: 0,
+        }
+    }
+
+    fn define(&mut self, name: &str) -> u32 {
+        let slot = self.slot_count;
+        self.locals.insert(name.to_string(), slot);
+        self.slot_count += 1;
+        slot
+    }
+
+    fn resolve(&self, name: &str) -> Option<u32> {
+        self.locals.get(name).copied()
+    }
+}
+
+struct FunctionCompiler {
+    scope: CompilerScope,
+    // Upvalues capture variables from the *immediate* enclosing function.
+    // The address stored here refers to a Local/Upvalue in the Parent Scope.
+    upvalues: Vec<Address>,
+}
+
+impl FunctionCompiler {
+    fn new() -> Self {
+        Self {
+            scope: CompilerScope::new(),
+            upvalues: Vec::new(),
+        }
+    }
+
+    fn add_upvalue(&mut self, addr: Address) -> u32 {
+        if let Some(idx) = self.upvalues.iter().position(|&a| a == addr) {
+            return idx as u32;
+        }
+        let idx = self.upvalues.len() as u32;
+        self.upvalues.push(addr);
+        idx
+    }
+}
+
+pub struct Binder {
+    functions: Vec<FunctionCompiler>,
+    globals: Arc<Mutex<HashMap<String, u32>>>,
+}
+
+impl Binder {
+    pub fn new(globals: Arc<Mutex<HashMap<String, u32>>>) -> Self {
+        let mut binder = Self {
+            functions: Vec::new(),
+            globals,
+        };
+        binder.functions.push(FunctionCompiler::new());
+        binder
+    }
+
+    pub fn bind(&mut self, node: &Node<UntypedKind>) -> Result<Node<BoundKind>, String> {
+        match &node.kind {
+            UntypedKind::Nop => Ok(self.make_node(node.identity.clone(), BoundKind::Nop)),
+            UntypedKind::Constant(v) => Ok(self.make_node(node.identity.clone(), BoundKind::Constant(v.clone()))),
+            
+            UntypedKind::Identifier(name) => {
+                let addr = self.resolve_variable(name)?;
+                Ok(self.make_node(node.identity.clone(), BoundKind::Get(addr)))
+            },
+
+            UntypedKind::If { cond, then_br, else_br } => {
+                let cond = Box::new(self.bind(cond)?);
+                let then_br = Box::new(self.bind(then_br)?);
+                let else_br = match else_br {
+                    Some(e) => Some(Box::new(self.bind(e)?)),
+                    None => None,
+                };
+                Ok(self.make_node(node.identity.clone(), BoundKind::If { cond, then_br, else_br }))
+            },
+
+            UntypedKind::Def { name, value } => {
+                // Determine scope: Global (root) or Local (inside fn)?
+                if self.functions.len() == 1 {
+                    // Global Definition
+                    let val_node = self.bind(value)?;
+                    let mut globals = self.globals.lock().unwrap();
+                    let idx = if let Some(&idx) = globals.get(name.as_ref()) {
+                        idx
+                    } else {
+                        let idx = globals.len() as u32;
+                        globals.insert(name.to_string(), idx);
+                        idx
+                    };
+                    Ok(self.make_node(node.identity.clone(), BoundKind::DefGlobal { global_index: idx, value: Box::new(val_node) }))
+                } else {
+                    // Local Variable Definition
+                    // We bind the value *before* defining the name to avoid self-reference in init?
+                    // Usually yes: (def x 10) -> bind(10), define(x).
+                    let val_node = self.bind(value)?;
+                    let current_fn = self.functions.last_mut().unwrap();
+                    let slot = current_fn.scope.define(name);
+                    
+                    // We treat local 'def' as a Set to the new slot
+                    Ok(self.make_node(node.identity.clone(), BoundKind::Set { 
+                        addr: Address::Local(slot), 
+                        value: Box::new(val_node) 
+                    }))
+                }
+            },
+
+            UntypedKind::Assign { target, value } => {
+                let val_node = self.bind(value)?;
+                
+                if let UntypedKind::Identifier(name) = &target.kind {
+                    let addr = self.resolve_variable(name)?;
+                    Ok(self.make_node(node.identity.clone(), BoundKind::Set { addr, value: Box::new(val_node) }))
+                } else {
+                    Err("Assignment target must be an identifier".to_string())
+                }
+            },
+
+            UntypedKind::Lambda { params, body } => {
+                self.functions.push(FunctionCompiler::new());
+                
+                {
+                    let current_fn = self.functions.last_mut().unwrap();
+                    for param in params {
+                        current_fn.scope.define(param);
+                    }
+                }
+
+                let body_bound = self.bind(body)?;
+
+                let compiled_fn = self.functions.pop().unwrap();
+                let upvalues = compiled_fn.upvalues;
+
+                Ok(self.make_node(node.identity.clone(), BoundKind::Lambda {
+                    param_count: params.len() as u32,
+                    upvalues,
+                    body: Arc::new(body_bound),
+                }))
+            },
+
+            UntypedKind::Call { callee, args } => {
+                let callee = Box::new(self.bind(callee)?);
+                let mut bound_args = Vec::new();
+                for arg in args {
+                    bound_args.push(self.bind(arg)?);
+                }
+                Ok(self.make_node(node.identity.clone(), BoundKind::Call { callee, args: bound_args }))
+            },
+
+            UntypedKind::Block { exprs } => {
+                let mut bound_exprs = Vec::new();
+                for expr in exprs {
+                    bound_exprs.push(self.bind(expr)?);
+                }
+                Ok(self.make_node(node.identity.clone(), BoundKind::Block { exprs: bound_exprs }))
+            },
+            
+            UntypedKind::Extension(_) => {
+                Err("Custom extensions not supported in Binder yet".to_string())
+            }
+        }
+    }
+
+    fn resolve_variable(&mut self, name: &str) -> Result<Address, String> {
+        let current_fn_idx = self.functions.len() - 1;
+
+        // 1. Try local in current function
+        if let Some(slot) = self.functions[current_fn_idx].scope.resolve(name) {
+            return Ok(Address::Local(slot));
+        }
+
+        // 2. Try enclosing scopes (capture chain)
+        let mut captured_addr: Option<Address> = None;
+
+        // Walk backwards from parent of current function up to root (0)
+        // We look for where the variable is DEFINED.
+        for i in (0..current_fn_idx).rev() {
+            let func = &self.functions[i];
+            if let Some(slot) = func.scope.resolve(name) {
+                // Found definition! It's a Local variable in function 'i'.
+                captured_addr = Some(Address::Local(slot));
+                
+                // Now we must propagate this capture down through all functions from i+1 to current.
+                let mut addr = captured_addr.unwrap();
+                for k in (i + 1)..=current_fn_idx {
+                    addr = Address::Upvalue(self.functions[k].add_upvalue(addr));
+                }
+                return Ok(addr);
+            }
+        }
+
+        // 3. Try Global
+        let globals = self.globals.lock().unwrap();
+        if let Some(&idx) = globals.get(name) {
+            return Ok(Address::Global(idx));
+        }
+
+        Err(format!("Undefined variable '{}'", name))
+    }
+
+    fn make_node(&self, identity: Identity, kind: BoundKind) -> Node<BoundKind> {
+        Node { identity, kind }
+    }
+}

src/ast/compiler/bound_nodes.rs

@@ -0,0 +1,56 @@
+use std::sync::Arc;
+use crate::ast::types::Value;
+use crate::ast::nodes::{Node, CustomNode};
+
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub enum Address {
+    Local(u32),   // Stack-Slot index (relative to frame base)
+    Upvalue(u32), // Index in the closure's upvalue array
+    Global(u32),  // Index in the global environment vector
+}
+
+#[derive(Debug)]
+pub enum BoundKind {
+    Nop,
+    Constant(Value),
+    
+    // Variable Access (Resolved)
+    Get(Address),
+    
+    // Variable Update (Resolved)
+    Set {
+        addr: Address,
+        value: Box<Node<BoundKind>>,
+    },
+
+    If {
+        cond: Box<Node<BoundKind>>,
+        then_br: Box<Node<BoundKind>>,
+        else_br: Option<Box<Node<BoundKind>>>,
+    },
+    
+    // Global Definition (Locals are implicit by stack position)
+    DefGlobal {
+        global_index: u32,
+        value: Box<Node<BoundKind>>,
+    },
+
+    Lambda {
+        param_count: u32,
+        // The list of variables captured from enclosing scopes
+        upvalues: Vec<Address>, 
+        body: Arc<Node<BoundKind>>,
+    },
+
+    Call {
+        callee: Box<Node<BoundKind>>,
+        args: Vec<Node<BoundKind>>,
+    },
+
+    Block {
+        exprs: Vec<Node<BoundKind>>,
+    },
+
+    // Extension points (need to be adapted for bound nodes if they use variables)
+    // For now, we assume extensions are self-contained or handled dynamically.
+}

src/ast/compiler/mod.rs

@@ -0,0 +1,5 @@
+pub mod binder;
+pub mod bound_nodes;
+
+pub use binder::*;
+pub use bound_nodes::*;

src/ast/environment.rs

@@ -0,0 +1,69 @@
+use std::sync::{Arc, Mutex};
+use std::collections::HashMap;
+use crate::ast::types::Value;
+use crate::ast::parser::Parser;
+use crate::ast::compiler::binder::Binder;
+use crate::ast::vm::VM;
+
+pub struct Environment {
+    pub global_names: Arc<Mutex<HashMap<String, u32>>>,
+    pub global_values: Arc<Mutex<Vec<Value>>>,
+}
+
+impl Environment {
+    pub fn new() -> Self {
+        let env = Self {
+            global_names: Arc::new(Mutex::new(HashMap::new())),
+            global_values: Arc::new(Mutex::new(Vec::new())),
+        };
+        env.register_stdlib();
+        env
+    }
+
+    pub fn register_native(&self, name: &str, func: fn(Vec<Value>) -> Value) {
+        let mut names = self.global_names.lock().unwrap();
+        let mut values = self.global_values.lock().unwrap();
+
+        let idx = values.len() as u32;
+        names.insert(name.to_string(), idx);
+        values.push(Value::Function(Arc::new(move |args| func(args))));
+    }
+
+    fn register_stdlib(&self) {
+        // Simple math for testing
+        self.register_native("+", |args| {
+            let mut acc = 0.0;
+            for arg in args {
+                if let Value::Int(i) = arg { acc += i as f64; }
+                else if let Value::Float(f) = arg { acc += f; }
+            }
+            if acc.fract() == 0.0 { Value::Int(acc as i64) } else { Value::Float(acc) }
+        });
+        
+        self.register_native(">", |args| {
+             if args.len() != 2 { return Value::Void; }
+             match (&args[0], &args[1]) {
+                 (Value::Int(a), Value::Int(b)) => Value::Bool(a > b),
+                 _ => Value::Bool(false),
+             }
+        });
+    }
+
+    pub fn run_script(&self, source: &str) -> Result<Value, String> {
+        // 1. Parse
+        let mut parser = Parser::new(source)?;
+        let untyped_ast = parser.parse_expression()?; // Or loop for script
+
+        // 2. Bind
+        let mut binder = Binder::new(self.global_names.clone());
+        let bound_ast = binder.bind(&untyped_ast)?;
+
+        // 3. Execute
+        // Note: VM needs to borrow globals, not own them exclusively?
+        // My VM impl takes Vec<Value>, but here we have Arc<Mutex<Vec>>.
+        // I need to update VM to accept shared globals.
+        
+        let mut vm = VM::new(self.global_values.clone());
+        vm.run(&bound_ast)
+    }
+}

src/ast/mod.rs

@@ -2,8 +2,14 @@ pub mod types;
 pub mod nodes;
 pub mod lexer;
 pub mod parser;
+pub mod compiler;
+pub mod vm;
+pub mod environment;
 
 pub use types::*;
 pub use nodes::*;
 pub use lexer::*;
 pub use parser::*;
+pub use compiler::*;
+pub use vm::*;
+pub use environment::*;

src/ast/types.rs

@@ -3,6 +3,7 @@ use std::collections::HashMap;
 use std::fmt;
 use std::sync::Mutex;
 use lazy_static::lazy_static;
+use std::any::Any;
 
 /// Simple source location
 #[derive(Debug, Clone, Copy)]
@@ -48,10 +49,16 @@ impl Keyword {
     }
 }
 
+/// Interface for custom objects (Closures, Series, Streams)
+pub trait Object: fmt::Debug + Send + Sync {
+    fn type_name(&self) -> &'static str;
+    fn as_any(&self) -> &dyn Any;
+}
+
 /// Core data value in Myc Script (similar to TDataValue)
 #[derive(Clone)]
 pub enum Value {
-    Void, // Maps to vkVoid
+    Void,
     Bool(bool),
     Int(i64),
     Float(f64),
@@ -60,6 +67,7 @@ pub enum Value {
     List(Arc<Vec<Value>>),
     Record(Arc<HashMap<Keyword, Value>>),
     Function(Arc<dyn Fn(Vec<Value>) -> Value + Send + Sync>),
+    Object(Arc<dyn Object>), // For compiled Closures and other opaque types
 }
 
 impl Value {
@@ -83,7 +91,8 @@ impl fmt::Display for Value {
             Value::Keyword(k) => write!(f, ":{}", k.name()),
             Value::List(l) => write!(f, "<list[{}]>", l.len()),
             Value::Record(r) => write!(f, "<record[{}]>", r.len()),
-            Value::Function(_) => write!(f, "<fn>"),
+            Value::Function(_) => write!(f, "<native fn>"),
+            Value::Object(o) => write!(f, "<{}>", o.type_name()),
         }
     }
 }

src/ast/vm.rs

@@ -0,0 +1,218 @@
+use std::sync::{Arc, Mutex};
+use std::any::Any;
+use crate::ast::compiler::bound_nodes::{Address, BoundKind};
+use crate::ast::nodes::Node;
+use crate::ast::types::{Value, Object};
+
+#[derive(Debug, Clone)]
+pub struct Closure {
+    pub function_node: Arc<Node<BoundKind>>,
+    pub upvalues: Vec<Value>,
+}
+
+impl Object for Closure {
+    fn type_name(&self) -> &'static str {
+        "closure"
+    }
+    fn as_any(&self) -> &dyn Any {
+        self
+    }
+}
+
+#[derive(Debug)]
+struct CallFrame {
+    stack_base: usize,
+    closure: Option<Arc<Closure>>,
+}
+
+pub struct VM {
+    stack: Vec<Value>,
+    globals: Arc<Mutex<Vec<Value>>>,
+    frames: Vec<CallFrame>,
+}
+
+impl VM {
+    pub fn new(globals: Arc<Mutex<Vec<Value>>>) -> Self {
+        Self {
+            stack: Vec::new(),
+            globals,
+            frames: Vec::new(),
+        }
+    }
+
+    pub fn run(&mut self, root: &Node<BoundKind>) -> Result<Value, String> {
+        self.stack.clear();
+        self.frames.clear();
+
+        // Push global script frame
+        self.frames.push(CallFrame {
+            stack_base: 0,
+            closure: None,
+        });
+        
+        let result = self.eval(root);
+        
+        self.frames.pop();
+        result
+    }
+
+    fn eval(&mut self, node: &Node<BoundKind>) -> Result<Value, String> {
+        match &node.kind {
+            BoundKind::Nop => Ok(Value::Void),
+            BoundKind::Constant(v) => Ok(v.clone()),
+
+            BoundKind::DefGlobal { global_index, value } => {
+                let val = self.eval(value)?;
+                let idx = *global_index as usize;
+                let mut globals = self.globals.lock().unwrap();
+                if idx >= globals.len() {
+                    globals.resize(idx + 1, Value::Void);
+                }
+                globals[idx] = val.clone();
+                Ok(val)
+            },
+
+            BoundKind::Get(addr) => self.get_value(*addr),
+            
+            BoundKind::Set { addr, value } => {
+                let val = self.eval(value)?;
+                self.set_value(*addr, val.clone())?;
+                Ok(val)
+            },
+
+            BoundKind::If { cond, then_br, else_br } => {
+                let c = self.eval(cond)?;
+                if c.is_truthy() {
+                    self.eval(then_br)
+                } else if let Some(e) = else_br {
+                    self.eval(e)
+                } else {
+                    Ok(Value::Void)
+                }
+            },
+
+            BoundKind::Block { exprs } => {
+                let mut last = Value::Void;
+                for e in exprs {
+                    last = self.eval(e)?;
+                }
+                Ok(last)
+            },
+
+            BoundKind::Lambda { param_count: _, upvalues, body } => {
+                let mut captured = Vec::with_capacity(upvalues.len());
+                for addr in upvalues {
+                    captured.push(self.get_value(*addr)?);
+                }
+
+                let closure = Closure {
+                    function_node: body.clone(),
+                    upvalues: captured,
+                };
+
+                Ok(Value::Object(Arc::new(closure)))
+            },
+
+            BoundKind::Call { callee, args } => {
+                let func_val = self.eval(callee)?;
+                
+                let mut arg_vals = Vec::with_capacity(args.len());
+                for arg in args {
+                    arg_vals.push(self.eval(arg)?);
+                }
+
+                match func_val {
+                    Value::Function(f) => Ok(f(arg_vals)),
+                    Value::Object(obj) => {
+                        if let Some(closure) = obj.as_any().downcast_ref::<Closure>() {
+                            let old_stack_top = self.stack.len();
+                            let closure_arc = Arc::new(closure.clone()); 
+                            
+                            self.stack.extend(arg_vals);
+                            
+                            self.frames.push(CallFrame {
+                                stack_base: old_stack_top,
+                                closure: Some(closure_arc.clone()),
+                            });
+
+                            let result = self.eval(&closure.function_node);
+
+                            self.frames.pop();
+                            self.stack.truncate(old_stack_top);
+                            
+                            result
+                        } else {
+                            Err(format!("Object is not a closure: {}", obj.type_name()))
+                        }
+                    },
+                    _ => Err(format!("Attempt to call non-function: {}", func_val)),
+                }
+            }
+        }
+    }
+
+    fn get_value(&self, addr: Address) -> Result<Value, String> {
+        match addr {
+            Address::Local(idx) => {
+                let frame = self.frames.last().ok_or("No call frame")?;
+                let abs_index = frame.stack_base + (idx as usize);
+                if abs_index < self.stack.len() {
+                    Ok(self.stack[abs_index].clone())
+                } else {
+                    Err(format!("Stack underflow access local {}", idx))
+                }
+            },
+            Address::Global(idx) => {
+                let idx = idx as usize;
+                let globals = self.globals.lock().unwrap();
+                if idx < globals.len() {
+                    Ok(globals[idx].clone())
+                } else {
+                    Err(format!("Global access out of bounds {}", idx))
+                }
+            },
+            Address::Upvalue(idx) => {
+                let frame = self.frames.last().ok_or("No call frame")?;
+                if let Some(closure) = &frame.closure {
+                    let idx = idx as usize;
+                    if idx < closure.upvalues.len() {
+                        Ok(closure.upvalues[idx].clone())
+                    } else {
+                        Err(format!("Upvalue access out of bounds {}", idx))
+                    }
+                } else {
+                    Err("Current frame has no closure (cannot access upvalues)".to_string())
+                }
+            }
+        }
+    }
+
+    fn set_value(&mut self, addr: Address, value: Value) -> Result<(), String> {
+        match addr {
+            Address::Local(idx) => {
+                let frame = self.frames.last().ok_or("No call frame")?;
+                let abs_index = frame.stack_base + (idx as usize);
+                if abs_index >= self.stack.len() {
+                    if abs_index == self.stack.len() {
+                        self.stack.push(value);
+                    } else {
+                        return Err(format!("Stack gap write local {}", idx));
+                    }
+                } else {
+                    self.stack[abs_index] = value;
+                }
+                Ok(())
+            },
+            Address::Global(idx) => {
+                let idx = idx as usize;
+                let mut globals = self.globals.lock().unwrap();
+                if idx >= globals.len() {
+                    globals.resize(idx + 1, Value::Void);
+                }
+                globals[idx] = value;
+                Ok(())
+            },
+            Address::Upvalue(_) => Err("Cannot assign to upvalue (Closure Upvalues are immutable)".to_string()),
+        }
+    }
+}

src/main.rs

@@ -1,4 +1,5 @@
 use eframe::egui;
+use crate::ast::environment::Environment;
 
 pub mod ast;
 
@@ -17,6 +18,7 @@ fn main() -> eframe::Result {
 struct CompilerApp {
     source_code: String,
     output_log: String,
+    env: Environment,
 }
 
 impl Default for CompilerApp {
@@ -24,6 +26,7 @@ impl Default for CompilerApp {
         Self {
             source_code: String::new(),
             output_log: String::from("Ready to compile..."),
+            env: Environment::new(),
         }
     }
 }
@@ -40,35 +43,16 @@ impl eframe::App for CompilerApp {
 
                 // Compile Button (at the top of the bottom panel)
                 if ui.button("Compile").clicked() {
-                    use crate::ast::parser::Parser;
-                    use crate::ast::nodes::Context;
-
-                    let mut parser = match Parser::new(&self.source_code) {
-                        Ok(p) => p,
-                        Err(e) => {
-                            self.output_log = format!("Lexer Error: {}", e);
-                            return;
-                        }
-                    };
-
-                    match parser.parse_expression() {
-                        Ok(ast) => {
-                            let mut context = Context::new(); // Use new() which registers stdlib
-                            match ast.eval(&mut context) {
+                    match self.env.run_script(&self.source_code) {
                         Ok(result) => {
                             self.output_log = format!(
-                                        "AST Parsed & Evaluated Successfully.\nResult: {}\n\nFinished at {:?}",
+                                "Execution Successful.\nResult: {}\n\nFinished at {:?}",
                                 result,
                                 std::time::SystemTime::now(),
                             );
                         }
                         Err(e) => {
-                                    self.output_log = format!("Runtime Error: {}", e);
-                                }
-                            }
-                        }
-                        Err(e) => {
-                            self.output_log = format!("Parser Error: {}", e);
+                            self.output_log = format!("Error: {}", e);
                         }
                     }
                 }