diff --git a/src/lib/exec.rs b/src/lib/exec.rs
index 0ab02e1357..5ac3e71b7a 100644
--- a/src/lib/exec.rs
+++ b/src/lib/exec.rs
@@ -1,11 +1,16 @@
-use gc::GcCell;
-use js::object::ObjectData;
-use js::value::{ResultValue, Value, ValueData};
-use js::{function, json, object};
+use gc::Gc;
+use js::value::{to_value, ResultValue, Value, ValueData};
+use js::{array, console, function, json, math, object, string};
 use std::borrow::Borrow;
-use std::cell::RefCell;
-use std::collections::HashMap;
-use syntax::ast::expr::Expr;
+use syntax::ast::constant::Const;
+use syntax::ast::expr::{Expr, ExprDef};
+/// A variable scope
+pub struct Scope {
+    /// The value of `this` in the scope
+    pub this: Value,
+    /// The variables declared in the scope
+    pub vars: Value,
+}
 
 /// An execution engine
 pub trait Executor {
@@ -16,29 +21,37 @@ pub trait Executor {
     /// Resolve the global variable `name`
     fn get_global(&self, name: String) -> Value;
     /// Create a new scope and return it
-    fn make_scope(&mut self) -> GcCell<RefCell<ObjectData>>;
+    fn make_scope(&mut self, this: Value) -> Scope;
     /// Destroy the current scope
-    fn destroy_scope(&mut self) -> ();
-    // fn run(&mut self, expr: &Expr) -> ResultValue;
+    fn destroy_scope(&mut self) -> Scope;
+    /// Run an expression
+    fn run(&mut self, expr: &Expr) -> ResultValue;
 }
 
 /// A Javascript intepreter
 pub struct Interpreter {
     /// An object representing the global object
     global: Value,
-    /// The variable scopes
-    scopes: Vec<GcCell<RefCell<ObjectData>>>,
+    /// The scopes
+    pub scopes: Vec<Scope>,
 }
 
-impl Executor for Interpreter {
+impl Executor<Expr> for Interpreter {
     fn new() -> Interpreter {
-        let global = ValueData::new_obj(None);
+        let global = Value::new_obj(None);
         object::init(global);
+        console::init(global);
+        math::init(global);
+        array::init(global);
         function::init(global);
         json::init(global);
+        string::init(global);
         Interpreter {
             global: global,
-            scopes: Vec::new(),
+            scopes: vec![Scope {
+                this: global,
+                vars: global,
+            }],
         }
     }
 
@@ -50,13 +63,326 @@ impl Executor for Interpreter {
         self.global.borrow().get_field(name)
     }
 
-    fn make_scope(&mut self) -> GcCell<RefCell<ObjectData>> {
-        let value = GcCell::new(RefCell::new(HashMap::new()));
-        self.scopes.push(value.clone());
-        value
+    fn make_scope(&mut self, this: Value) -> Scope {
+        let scope = Scope {
+            this: this,
+            vars: Value::new_obj(None),
+        };
+        self.scopes.push(scope);
+        scope
+    }
+
+    fn destroy_scope(&mut self) -> Scope {
+        self.scopes.pop().unwrap()
     }
 
-    fn destroy_scope(&mut self) -> () {
-        self.scopes.pop();
+    fn compile<'a>(&self, expr: &'a Expr) -> &'a Expr {
+        expr
+    }
+
+    fn run(&mut self, expr: &Expr) -> ResultValue {
+        match expr.def {
+            ExprDef::ConstExpr(Const::Null) => Ok(to_value(None)),
+            ExprDef::ConstExpr(Const::Undefined) => Ok(Value::undefined()),
+            ExprDef::ConstExpr(Const::Num(num)) => Ok(to_value(num)),
+            ExprDef::ConstExpr(Const::Int(num)) => Ok(to_value(num)),
+            ExprDef::ConstExpr(Const::String(str)) => Ok(to_value(str)),
+            ExprDef::ConstExpr(Const::Bool(val)) => Ok(to_value(val)),
+            ExprDef::ConstExpr(Const::RegExp(_, _, _)) => Ok(to_value(None)),
+            ExprDef::BlockExpr(ref es) => {
+                let mut obj = to_value(None);
+                for e in es.iter() {
+                    let val = try!(self.run(e));
+                    if e == es.last().unwrap() {
+                        obj = val;
+                    }
+                }
+                Ok(obj)
+            }
+            ExprDef::LocalExpr(ref name) => {
+                let mut val = Value::undefined();
+                for scope in self.scopes.iter().rev() {
+                    let vars = scope.vars;
+                    let vars_ptr = vars.borrow();
+                    match *vars_ptr.ptr {
+                        ValueData::Object(ref obj) => match obj.borrow().get(name) {
+                            Some(v) => {
+                                val = v.value;
+                                break;
+                            }
+                            None => (),
+                        },
+                        _ => unreachable!(),
+                    }
+                }
+                Ok(val)
+            }
+            ExprDef::GetConstFieldExpr(ref obj, ref field) => {
+                let val_obj = try!(self.run(obj));
+                Ok(val_obj.borrow().get_field(field.clone()))
+            }
+            ExprDef::GetFieldExpr(ref obj, ref field) => {
+                let val_obj = try!(self.run(obj));
+                let val_field = try!(self.run(field));
+                Ok(val_obj.borrow().get_field(val_field.borrow().to_string()))
+            }
+            ExprDef::CallExpr(ref callee, ref args) => {
+                let (this, func) = match callee.def {
+                    ExprDef::GetConstFieldExpr(ref obj, ref field) => {
+                        let obj = try!(self.run(obj));
+                        (obj, obj.borrow().get_field(field.clone()))
+                    }
+                    ExprDef::GetFieldExpr(ref obj, ref field) => {
+                        let obj = try!(self.run(obj));
+                        let field = try!(self.run(field));
+                        (obj, obj.borrow().get_field(field.borrow().to_string()))
+                    }
+                    _ => (self.global.clone(), try!(self.run(&callee.clone()))),
+                };
+                let mut v_args = Vec::with_capacity(args.len());
+                for arg in args.iter() {
+                    v_args.push(try!(self.run(arg)));
+                }
+                match *func.borrow().ptr {
+                    ValueData::Function(ref func) => match *func.borrow() {
+                        NativeFunc(ref ntv) => {
+                            let func = ntv.data;
+                            func(this, try!(self.run(*callee)), v_args)
+                        }
+                        RegularFunc(ref data) => {
+                            let scope = self.make_scope(this);
+                            let scope_vars_ptr = scope.vars.borrow();
+                            for i in range(0, data.args.len()) {
+                                let name = data.args.get(i);
+                                let expr = v_args.get(i);
+                                scope_vars_ptr.set_field(name.clone(), *expr);
+                            }
+                            let result = self.run(&data.expr);
+                            self.destroy_scope();
+                            result
+                        }
+                    },
+                    _ => Err(Gc::new(VUndefined)),
+                }
+            }
+            WhileLoopExpr(ref cond, ref expr) => {
+                let mut result = Gc::new(VUndefined);
+                while try!(self.run(*cond)).borrow().is_true() {
+                    result = try!(self.run(*expr));
+                }
+                Ok(result)
+            }
+            IfExpr(ref cond, ref expr, None) => Ok(if try!(self.run(*cond)).borrow().is_true() {
+                try!(self.run(*expr))
+            } else {
+                Gc::new(VUndefined)
+            }),
+            IfExpr(ref cond, ref expr, Some(ref else_e)) => {
+                Ok(if try!(self.run(*cond)).borrow().is_true() {
+                    try!(self.run(*expr))
+                } else {
+                    try!(self.run(*else_e))
+                })
+            }
+            SwitchExpr(ref val_e, ref vals, ref default) => {
+                let val = try!(self.run(*val_e)).borrow().clone();
+                let mut result = Gc::new(ValueData::Null);
+                let mut matched = false;
+                for tup in vals.iter() {
+                    let tup: &(Expr, Vec<Expr>) = tup;
+                    match *tup {
+                        (ref cond, ref block) if (val == *try!(self.run(cond)).borrow()) => {
+                            matched = true;
+                            let last_expr = block.last().unwrap();
+                            for expr in block.iter() {
+                                let e_result = try!(self.run(expr));
+                                if expr == last_expr {
+                                    result = e_result;
+                                }
+                            }
+                        }
+                        _ => (),
+                    }
+                }
+                if !matched && default.is_some() {
+                    result = try!(self.run(*default.as_ref().unwrap()));
+                }
+                Ok(result)
+            }
+            ObjectDeclExpr(ref map) => {
+                let obj = ValueData::new_obj(Some(self.global));
+                for (key, val) in map.iter() {
+                    obj.borrow().set_field(key.clone(), try!(self.run(val)));
+                }
+                Ok(obj)
+            }
+            ArrayDeclExpr(ref arr) => {
+                let arr_map = ValueData::new_obj(Some(self.global));
+                let mut index: i32 = 0;
+                for val in arr.iter() {
+                    let val = try!(self.run(val));
+                    arr_map.borrow().set_field(index.to_str(), val);
+                    index += 1;
+                }
+                arr_map.borrow().set_field_slice(
+                    INSTANCE_PROTOTYPE,
+                    self.get_global("Array".into_strbuf())
+                        .borrow()
+                        .get_field_slice(PROTOTYPE),
+                );
+                arr_map.borrow().set_field_slice("length", to_value(index));
+                Ok(arr_map)
+            }
+            FunctionDeclExpr(ref name, ref args, ref expr) => {
+                let function = RegularFunc(RegularFunction::new(*expr.clone(), args.clone()));
+                let val = Gc::new(VFunction(RefCell::new(function)));
+                if name.is_some() {
+                    self.global.borrow().set_field(name.clone().unwrap(), val);
+                }
+                Ok(val)
+            }
+            ArrowFunctionDeclExpr(ref args, ref expr) => {
+                let function = RegularFunc(RegularFunction::new(*expr.clone(), args.clone()));
+                Ok(Gc::new(VFunction(RefCell::new(function))))
+            }
+            BinOpExpr(BinNum(ref op), ref a, ref b) => {
+                let v_r_a = try!(self.run(*a));
+                let v_r_b = try!(self.run(*b));
+                let v_a = v_r_a.borrow();
+                let v_b = v_r_b.borrow();
+                Ok(Gc::new(match *op {
+                    OpAdd => *v_a + *v_b,
+                    OpSub => *v_a - *v_b,
+                    OpMul => *v_a * *v_b,
+                    OpDiv => *v_a / *v_b,
+                    OpMod => *v_a % *v_b,
+                }))
+            }
+            UnaryOpExpr(ref op, ref a) => {
+                let v_r_a = try!(self.run(*a));
+                let v_a = v_r_a.borrow();
+                Ok(match *op {
+                    UnaryMinus => to_value(-v_a.to_num()),
+                    UnaryPlus => to_value(v_a.to_num()),
+                    UnaryNot => Gc::new(!v_a),
+                    _ => unreachable!(),
+                })
+            }
+            BinOpExpr(BinBit(ref op), ref a, ref b) => {
+                let v_r_a = try!(self.run(*a));
+                let v_r_b = try!(self.run(*b));
+                let v_a = v_r_a.borrow();
+                let v_b = v_r_b.borrow();
+                Ok(Gc::new(match *op {
+                    BitAnd => *v_a & *v_b,
+                    BitOr => *v_a | *v_b,
+                    BitXor => *v_a ^ *v_b,
+                    BitShl => *v_a << *v_b,
+                    BitShr => *v_a >> *v_b,
+                }))
+            }
+            BinOpExpr(BinComp(ref op), ref a, ref b) => {
+                let v_r_a = try!(self.run(*a));
+                let v_r_b = try!(self.run(*b));
+                let v_a = v_r_a.borrow();
+                let v_b = v_r_b.borrow();
+                Ok(to_value(match *op {
+                    CompEqual if v_a.is_object() => v_r_a.ptr_eq(&v_r_b),
+                    CompEqual => v_a == v_b,
+                    CompNotEqual if v_a.is_object() => !v_r_a.ptr_eq(&v_r_b),
+                    CompNotEqual => v_a != v_b,
+                    CompStrictEqual if v_a.is_object() => v_r_a.ptr_eq(&v_r_b),
+                    CompStrictEqual => v_a == v_b,
+                    CompStrictNotEqual if v_a.is_object() => !v_r_a.ptr_eq(&v_r_b),
+                    CompStrictNotEqual => v_a != v_b,
+                    CompGreaterThan => v_a.to_num() > v_b.to_num(),
+                    CompGreaterThanOrEqual => v_a.to_num() >= v_b.to_num(),
+                    CompLessThan => v_a.to_num() < v_b.to_num(),
+                    CompLessThanOrEqual => v_a.to_num() <= v_b.to_num(),
+                }))
+            }
+            BinOpExpr(BinLog(ref op), ref a, ref b) => {
+                let v_a = from_value::<bool>(try!(self.run(*a))).unwrap();
+                let v_b = from_value::<bool>(try!(self.run(*b))).unwrap();
+                Ok(match *op {
+                    LogAnd => to_value(v_a && v_b),
+                    LogOr => to_value(v_a || v_b),
+                })
+            }
+            ConstructExpr(ref callee, ref args) => {
+                let func = try!(self.run(*callee));
+                let mut v_args = Vec::with_capacity(args.len());
+                for arg in args.iter() {
+                    v_args.push(try!(self.run(arg)));
+                }
+                let this = Gc::new(VObject(RefCell::new(TreeMap::new())));
+                this.borrow()
+                    .set_field_slice(INSTANCE_PROTOTYPE, func.borrow().get_field_slice(PROTOTYPE));
+                match *func.borrow() {
+                    VFunction(ref func) => match *func.borrow() {
+                        NativeFunc(ref ntv) => {
+                            let func = ntv.data;
+                            func(this, try!(self.run(*callee)), v_args)
+                        }
+                        RegularFunc(ref data) => {
+                            let scope = self.make_scope(this);
+                            let scope_vars_ptr = scope.vars.borrow();
+                            for i in range(0, data.args.len()) {
+                                let name = data.args.get(i);
+                                let expr = v_args.get(i);
+                                scope_vars_ptr.set_field(name.clone(), *expr);
+                            }
+                            let result = self.run(&data.expr);
+                            self.destroy_scope();
+                            result
+                        }
+                    },
+                    _ => Ok(Gc::new(VUndefined)),
+                }
+            }
+            ReturnExpr(ref ret) => match *ret {
+                Some(ref v) => self.run(*v),
+                None => Ok(Gc::new(VUndefined)),
+            },
+            ThrowExpr(ref ex) => Err(try!(self.run(*ex))),
+            AssignExpr(ref ref_e, ref val_e) => {
+                let val = try!(self.run(*val_e));
+                match ref_e.def {
+                    LocalExpr(ref name) => {
+                        self.scope().vars.borrow().set_field(name.clone(), val);
+                    }
+                    GetConstFieldExpr(ref obj, ref field) => {
+                        let val_obj = try!(self.run(*obj));
+                        val_obj.borrow().set_field(field.clone(), val);
+                    }
+                    _ => (),
+                }
+                Ok(val)
+            }
+            VarDeclExpr(ref vars) => {
+                let scope_vars = self.scope().vars;
+                let scope_vars_ptr = scope_vars.borrow();
+                for var in vars.iter() {
+                    let (name, value) = var.clone();
+                    let val = match value {
+                        Some(v) => try!(self.run(&v)),
+                        None => Gc::new(ValueData::Null),
+                    };
+                    scope_vars_ptr.set_field(name.clone(), val);
+                }
+                Ok(Gc::new(VUndefined))
+            }
+            TypeOfExpr(ref val_e) => {
+                let val = try!(self.run(*val_e));
+                Ok(to_value(match *val.borrow() {
+                    VUndefined => "undefined",
+                    ValueData::Null | VObject(_) => "object",
+                    VBoolean(_) => "boolean",
+                    VNumber(_) | VInteger(_) => "number",
+                    VString(_) => "string",
+                    VFunction(_) => "function",
+                }))
+            }
+        }
     }
 }
diff --git a/src/lib/js/function.rs b/src/lib/js/function.rs
index 52662cb55b..46c3707146 100644
--- a/src/lib/js/function.rs
+++ b/src/lib/js/function.rs
@@ -1,52 +1,69 @@
-use gc::{Gc, GcCell};
+use gc::Gc;
 use js::object::{ObjectData, Property};
 use js::value::{to_value, ResultValue, Value, ValueData};
 use std::collections::HashMap;
-use std::iter::FromIterator;
+use syntax::ast::expr::Expr;
 
 pub type FunctionData = fn(Vec<Value>, Value, Value, Value) -> ResultValue;
+pub type NativeFunctionData = fn(Value, Value, Vec<Value>) -> ResultValue;
 /// A Javascript function
 /// A member of the Object type that may be invoked as a subroutine
 /// https://tc39.github.io/ecma262/#sec-terms-and-definitions-function
 /// In our implementation, Function is extending Object by holding an object field which some extra data
 
+/// A Javascript function
+#[derive(Trace, Finalize, Debug)]
+pub enum Function {
+    /// A native javascript function
+    NativeFunc(NativeFunction),
+    /// A regular javascript function
+    RegularFunc(RegularFunction),
+}
+
+/// Represents a regular javascript function in memory
 #[derive(Trace, Finalize, Debug)]
-pub struct Function {
+pub struct RegularFunction {
     /// The fields associated with the function
     pub object: ObjectData,
-    /// This function's JIT representation
-    pub repr: FunctionData,
+    /// This function's expression
+    pub expr: Expr,
     /// The argument names of the function
     pub args: Vec<String>,
 }
 
-impl Function {
-    /// Make a new function
-    pub fn new(repr: FunctionData, args: Vec<String>) -> Function {
+impl RegularFunction {
+    /// Make a new regular function
+    pub fn new(expr: Expr, args: Vec<String>) -> RegularFunction {
         let mut obj = HashMap::new();
         obj.insert(
             "arguments".to_string(),
-            Property::from_value(to_value(args.len() as i32)),
+            Property::new(Gc::new(ValueData::Integer(args.len() as i32))),
         );
-        Function {
+        RegularFunction {
             object: obj,
-            repr: repr,
+            expr: expr,
             args: args,
         }
     }
-    /// Create a function from function data and arguments
-    pub fn make(repr: FunctionData, args: &[&'static str]) -> Value {
-        Value {
-            ptr: Gc::new(ValueData::Function(GcCell::new(Function::new(
-                repr,
-                FromIterator::from_iter(args.iter().map(|arg| arg.to_string())),
-            )))),
+}
+
+#[derive(Trace, Finalize, Debug)]
+/// Represents a native javascript function in memory
+pub struct NativeFunction {
+    /// The fields associated with the function
+    pub object: ObjectData,
+    /// The callable function data
+    pub data: NativeFunctionData,
+}
+impl NativeFunction {
+    /// Make a new native function with the given function data
+    pub fn new(data: NativeFunctionData) -> NativeFunction {
+        let obj = HashMap::new();
+        NativeFunction {
+            object: obj,
+            data: data,
         }
     }
-    /// Call with some args
-    pub fn call(&self, args: Vec<Value>, global: Value, scope: Value, this: Value) -> ResultValue {
-        (self.repr)(args, global, scope, this)
-    }
 }
 
 /// Create a new `Function` object
@@ -56,5 +73,6 @@ pub fn _create() -> Value {
 }
 /// Initialise the global object with the `Function` object
 pub fn init(global: Value) {
-    global.set_field_slice("Function", _create());
+    let global_ptr = global.borrow();
+    global_ptr.set_field_slice("Function", _create(global));
 }
diff --git a/src/lib/js/math.rs b/src/lib/js/math.rs
index ea5d2fc6bf..c00b7728e8 100644
--- a/src/lib/js/math.rs
+++ b/src/lib/js/math.rs
@@ -6,7 +6,9 @@ use std::f64;
 /// Get the absolute value of a number
 pub fn abs(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
     Ok(to_value(if args.len() >= 1 {
-        from_value::<f64>(*args.get(0)).unwrap().abs()
+        from_value::<f64>(args.get(0).unwrap().clone())
+            .unwrap()
+            .abs()
     } else {
         f64::NAN
     }))
@@ -14,7 +16,9 @@ pub fn abs(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
 /// Get the arccos of a number
 pub fn acos(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
     Ok(to_value(if args.len() >= 1 {
-        from_value::<f64>(*args.get(0)).unwrap().acos()
+        from_value::<f64>(args.get(0).unwrap().clone())
+            .unwrap()
+            .acos()
     } else {
         f64::NAN
     }))
@@ -22,7 +26,9 @@ pub fn acos(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
 /// Get the arcsine of a number
 pub fn asin(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
     Ok(to_value(if args.len() >= 1 {
-        from_value::<f64>(*args.get(0)).unwrap().asin()
+        from_value::<f64>(args.get(0).unwrap().clone())
+            .unwrap()
+            .asin()
     } else {
         f64::NAN
     }))
@@ -30,7 +36,9 @@ pub fn asin(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
 /// Get the arctangent of a number
 pub fn atan(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
     Ok(to_value(if args.len() >= 1 {
-        from_value::<f64>(*args.get(0)).unwrap().atan()
+        from_value::<f64>(args.get(0).unwrap().clone())
+            .unwrap()
+            .atan()
     } else {
         f64::NAN
     }))
@@ -38,9 +46,9 @@ pub fn atan(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
 /// Get the arctangent of a numbers
 pub fn atan2(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
     Ok(to_value(if args.len() >= 1 {
-        from_value::<f64>(*args.get(0))
+        from_value::<f64>(args.get(0).unwrap().clone())
             .unwrap()
-            .atan2(args.get(1).to_num())
+            .atan2(args.get(1).unwrap().to_num())
     } else {
         f64::NAN
     }))
@@ -48,7 +56,9 @@ pub fn atan2(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
 /// Get the cubic root of a number
 pub fn cbrt(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
     Ok(to_value(if args.len() >= 1 {
-        from_value::<f64>(*args.get(0)).unwrap().cbrt()
+        from_value::<f64>(args.get(0).unwrap().clone())
+            .unwrap()
+            .cbrt()
     } else {
         f64::NAN
     }))
@@ -56,7 +66,9 @@ pub fn cbrt(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
 /// Get lowest integer above a number
 pub fn ceil(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
     Ok(to_value(if args.len() >= 1 {
-        from_value::<f64>(*args.get(0)).unwrap().ceil()
+        from_value::<f64>(args.get(0).unwrap().clone())
+            .unwrap()
+            .ceil()
     } else {
         f64::NAN
     }))
@@ -64,7 +76,9 @@ pub fn ceil(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
 /// Get the cosine of a number
 pub fn cos(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
     Ok(to_value(if args.len() >= 1 {
-        from_value::<f64>(*args.get(0)).unwrap().cos()
+        from_value::<f64>(args.get(0).unwrap().clone())
+            .unwrap()
+            .cos()
     } else {
         f64::NAN
     }))
@@ -72,7 +86,9 @@ pub fn cos(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
 /// Get the power to raise the natural logarithm to get the number
 pub fn exp(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
     Ok(to_value(if args.len() >= 1 {
-        from_value::<f64>(*args.get(0)).unwrap().exp()
+        from_value::<f64>(args.get(0).unwrap().clone())
+            .unwrap()
+            .exp()
     } else {
         f64::NAN
     }))
@@ -80,7 +96,9 @@ pub fn exp(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
 /// Get the highest integer below a number
 pub fn floor(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
     Ok(to_value(if args.len() >= 1 {
-        from_value::<f64>(*args.get(0)).unwrap().floor()
+        from_value::<f64>(args.get(0).unwrap().clone())
+            .unwrap()
+            .floor()
     } else {
         f64::NAN
     }))
@@ -88,7 +106,9 @@ pub fn floor(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
 /// Get the natural logarithm of a number
 pub fn log(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
     Ok(to_value(if args.len() >= 1 {
-        from_value::<f64>(*args.get(0)).unwrap().log(f64::consts::E)
+        from_value::<f64>(args.get(0).unwrap().clone())
+            .unwrap()
+            .log(f64::consts::E)
     } else {
         f64::NAN
     }))
@@ -114,8 +134,8 @@ pub fn min(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
 /// Raise a number to a power
 pub fn pow(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
     Ok(to_value(if args.len() >= 2 {
-        let num: f64 = from_value(*args.get(0)).unwrap();
-        let power: f64 = from_value(*args.get(1)).unwrap();
+        let num: f64 = from_value(args.get(0).unwrap().clone()).unwrap();
+        let power: f64 = from_value(args.get(1).unwrap().clone()).unwrap();
         num.powf(power)
     } else {
         f64::NAN
@@ -128,7 +148,9 @@ pub fn _random(_: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
 /// Round a number to the nearest integer
 pub fn round(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
     Ok(to_value(if args.len() >= 1 {
-        from_value::<f64>(*args.get(0)).unwrap().round()
+        from_value::<f64>(args.get(0).unwrap().clone())
+            .unwrap()
+            .round()
     } else {
         f64::NAN
     }))
@@ -136,7 +158,9 @@ pub fn round(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
 /// Get the sine of a number
 pub fn sin(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
     Ok(to_value(if args.len() >= 1 {
-        from_value::<f64>(*args.get(0)).unwrap().sin()
+        from_value::<f64>(args.get(0).unwrap().clone())
+            .unwrap()
+            .sin()
     } else {
         f64::NAN
     }))
@@ -144,7 +168,9 @@ pub fn sin(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
 /// Get the square root of a number
 pub fn sqrt(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
     Ok(to_value(if args.len() >= 1 {
-        from_value::<f64>(*args.get(0)).unwrap().sqrt()
+        from_value::<f64>(args.get(0).unwrap().clone())
+            .unwrap()
+            .sqrt()
     } else {
         f64::NAN
     }))
@@ -152,7 +178,9 @@ pub fn sqrt(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
 /// Get the tangent of a number
 pub fn tan(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
     Ok(to_value(if args.len() >= 1 {
-        from_value::<f64>(*args.get(0)).unwrap().tan()
+        from_value::<f64>(args.get(0).unwrap().clone())
+            .unwrap()
+            .tan()
     } else {
         f64::NAN
     }))
@@ -166,30 +194,30 @@ pub fn _create(global: Value) -> Value {
     math.set_field_slice("LOG2E", to_value(f64::consts::LOG2_E));
     math.set_field_slice("LOG10E", to_value(f64::consts::LOG10_E));
     math.set_field_slice("SQRT1_2", to_value(0.5f64.sqrt()));
-    math.set_field_slice("SQRT2", to_value(f64::consts::SQRT2));
+    math.set_field_slice("SQRT2", to_value(f64::consts::SQRT_2));
     math.set_field_slice("PI", to_value(f64::consts::PI));
-    math.set_field_slice("abs", Function::make(abs, ["num1", "num2"]));
-    math.set_field_slice("acos", Function::make(acos, ["num1", "num2"]));
-    math.set_field_slice("asin", Function::make(asin, ["num1", "num2"]));
-    math.set_field_slice("atan", Function::make(atan, ["num1", "num2"]));
-    math.set_field_slice("atan2", Function::make(atan2, ["num1", "num2"]));
-    math.set_field_slice("cbrt", Function::make(cbrt, ["num1", "num2"]));
-    math.set_field_slice("ceil", Function::make(ceil, ["num1", "num2"]));
-    math.set_field_slice("cos", Function::make(cos, ["num1", "num2"]));
-    math.set_field_slice("exp", Function::make(exp, ["num1", "num2"]));
-    math.set_field_slice("floor", Function::make(floor, ["num"]));
-    math.set_field_slice("log", Function::make(log, ["num1", "num2"]));
-    math.set_field_slice("max", Function::make(max, ["num1", "num2"]));
-    math.set_field_slice("min", Function::make(min, ["num1", "num2"]));
-    math.set_field_slice("pow", Function::make(pow, ["num1", "num2"]));
-    math.set_field_slice("random", Function::make(_random, []));
-    math.set_field_slice("round", Function::make(round, ["num"]));
-    math.set_field_slice("sin", Function::make(sin, ["num"]));
-    math.set_field_slice("sqrt", Function::make(sqrt, ["num"]));
-    math.set_field_slice("tan", Function::make(tan, ["num"]));
+    math.set_field_slice("abs", Function::make(abs, &["num1", "num2"]));
+    math.set_field_slice("acos", Function::make(acos, &["num1", "num2"]));
+    math.set_field_slice("asin", Function::make(asin, &["num1", "num2"]));
+    math.set_field_slice("atan", Function::make(atan, &["num1", "num2"]));
+    math.set_field_slice("atan2", Function::make(atan2, &["num1", "num2"]));
+    math.set_field_slice("cbrt", Function::make(cbrt, &["num1", "num2"]));
+    math.set_field_slice("ceil", Function::make(ceil, &["num1", "num2"]));
+    math.set_field_slice("cos", Function::make(cos, &["num1", "num2"]));
+    math.set_field_slice("exp", Function::make(exp, &["num1", "num2"]));
+    math.set_field_slice("floor", Function::make(floor, &["num"]));
+    math.set_field_slice("log", Function::make(log, &["num1", "num2"]));
+    math.set_field_slice("max", Function::make(max, &["num1", "num2"]));
+    math.set_field_slice("min", Function::make(min, &["num1", "num2"]));
+    math.set_field_slice("pow", Function::make(pow, &["num1", "num2"]));
+    math.set_field_slice("random", Function::make(_random, &[]));
+    math.set_field_slice("round", Function::make(round, &["num"]));
+    math.set_field_slice("sin", Function::make(sin, &["num"]));
+    math.set_field_slice("sqrt", Function::make(sqrt, &["num"]));
+    math.set_field_slice("tan", Function::make(tan, &["num"]));
     math
 }
 /// Initialise the `Math` object on the global object
 pub fn init(global: Value) {
-    global.set_field_slice("Math", _create(global));
+    global.set_field_slice("Math", _create(global.clone()));
 }
diff --git a/src/lib/js/mod.rs b/src/lib/js/mod.rs
index 4dd2a8347d..95a998b1d7 100644
--- a/src/lib/js/mod.rs
+++ b/src/lib/js/mod.rs
@@ -8,7 +8,11 @@ pub mod error;
 pub mod function;
 /// The global `JSON` object
 pub mod json;
+/// The global `Math` object
+pub mod math;
 /// The global `Object` object
 pub mod object;
+/// The global `String` object
+pub mod string;
 /// Javascript values, utility methods and conversion between Javascript values and Rust values
 pub mod value;
diff --git a/src/lib/js/object.rs b/src/lib/js/object.rs
index 776d2695a9..e78f22b2d9 100644
--- a/src/lib/js/object.rs
+++ b/src/lib/js/object.rs
@@ -1,4 +1,5 @@
-use js::value::Value;
+use js::function::Function;
+use js::value::{from_value, to_value, FromValue, ResultValue, ToValue, Value};
 use std::collections::HashMap;
 pub static PROTOTYPE: &'static str = "prototype";
 pub static INSTANCE_PROTOTYPE: &'static str = "__proto__";
@@ -26,26 +27,113 @@ pub struct Property {
 
 impl Property {
     /// Make a new property with the given value
-    pub fn new() -> Property {
+    pub fn new(value: Value) -> Property {
         Property {
             configurable: false,
             enumerable: false,
             writable: false,
-            value: Value::undefined(),
+            value: value,
             get: Value::undefined(),
             set: Value::undefined(),
         }
     }
+}
 
-    /// Make a new property with the given value
-    pub fn from_value(value: Value) -> Property {
-        Property {
-            configurable: false,
-            enumerable: false,
-            writable: false,
-            value: value,
-            get: Value::undefined(),
-            set: Value::undefined(),
-        }
+impl ToValue for Property {
+    fn to_value(&self) -> Value {
+        let prop = Value::new_obj(None);
+        prop.set_field_slice("configurable", to_value(self.configurable));
+        prop.set_field_slice("enumerable", to_value(self.enumerable));
+        prop.set_field_slice("writable", to_value(self.writable));
+        prop.set_field_slice("value", self.value.clone());
+        prop.set_field_slice("get", self.get.clone());
+        prop.set_field_slice("set", self.set.clone());
+        prop
     }
 }
+
+impl FromValue for Property {
+    fn from_value(v: Value) -> Result<Property, &'static str> {
+        Ok(Property {
+            configurable: from_value(v.get_field_slice("configurable")).unwrap(),
+            enumerable: from_value(v.get_field_slice("enumerable")).unwrap(),
+            writable: from_value(v.get_field_slice("writable")).unwrap(),
+            value: v.get_field_slice("value"),
+            get: v.get_field_slice("get"),
+            set: v.get_field_slice("set"),
+        })
+    }
+}
+
+/// Create a new object
+pub fn make_object(_: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
+    Ok(Value::undefined())
+}
+
+/// Get the prototype of an object
+pub fn get_proto_of(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
+    let obj = args.get(0).unwrap();
+    Ok(obj.get_field_slice(INSTANCE_PROTOTYPE))
+}
+
+/// Set the prototype of an object
+pub fn set_proto_of(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
+    let obj = args.get(0).unwrap().clone();
+    let proto = args.get(1).unwrap().clone();
+    obj.set_field_slice(INSTANCE_PROTOTYPE, proto);
+    Ok(obj)
+}
+
+/// Define a property in an object
+pub fn define_prop(args: Vec<Value>, _: Value, _: Value, _: Value) -> ResultValue {
+    let obj = args.get(0).unwrap();
+    let prop = from_value::<String>(args.get(1).unwrap().clone()).unwrap();
+    let desc = from_value::<Property>(args.get(2).unwrap().clone()).unwrap();
+    obj.set_prop(prop, desc);
+    Ok(Value::undefined())
+}
+
+/// To string
+pub fn to_string(_: Vec<Value>, _: Value, _: Value, this: Value) -> ResultValue {
+    Ok(to_value(this.to_string()))
+}
+
+/// Check if it has a property
+pub fn has_own_prop(args: Vec<Value>, _: Value, _: Value, this: Value) -> ResultValue {
+    let prop = if args.len() == 0 {
+        None
+    } else {
+        from_value::<String>(args.get(0).unwrap().clone()).ok()
+    };
+    Ok(to_value(
+        prop.is_some() && this.get_prop(prop.unwrap()).is_some(),
+    ))
+}
+
+/// Create a new `Object` object
+pub fn _create(global: Value) -> Value {
+    let object = Function::make(make_object, &[]);
+    let prototype = Value::new_obj(Some(global));
+    prototype.set_field_slice(
+        "hasOwnProperty",
+        Function::make(has_own_prop, &["property"]),
+    );
+    prototype.set_field_slice("toString", Function::make(to_string, &[]));
+    object.set_field_slice("length", to_value(1i32));
+    object.set_field_slice(PROTOTYPE, prototype);
+    object.set_field_slice(
+        "setPrototypeOf",
+        Function::make(get_proto_of, &["object", "prototype"]),
+    );
+    object.set_field_slice("getPrototypeOf", Function::make(get_proto_of, &["object"]));
+    object.set_field_slice(
+        "defineProperty",
+        Function::make(define_prop, &["object", "property"]),
+    );
+    object
+}
+
+/// Initialise the `Object` object on the global object
+pub fn init(global: Value) {
+    global.set_field_slice("Object", _create(global.clone()));
+}
diff --git a/src/lib/js/string.rs b/src/lib/js/string.rs
index f52b77d050..3c9eff16d9 100644
--- a/src/lib/js/string.rs
+++ b/src/lib/js/string.rs
@@ -14,14 +14,14 @@ pub fn get_string_length(_: Vec<Value>, _: Value, _: Value, this: Value) -> Resu
 }
 /// Create a new `String` object
 pub fn _create(global: Value) -> Value {
-    let string = Function::make(make_string, ["string"]);
+    let string = Function::make(make_string, &["string"]);
     let proto = Value::new_obj(Some(global));
     let prop = Property {
         configurable: false,
         enumerable: false,
         writable: false,
         value: Value::undefined(),
-        get: Function::make(get_string_length, []),
+        get: Function::make(get_string_length, &[]),
         set: Value::undefined(),
     };
     proto.set_prop_slice("length", prop);
diff --git a/src/lib/js/value.rs b/src/lib/js/value.rs
index 2cecc847aa..e1e8fc6e4d 100644
--- a/src/lib/js/value.rs
+++ b/src/lib/js/value.rs
@@ -9,16 +9,13 @@ use std::f64::NAN;
 use std::fmt::{Display, Formatter, Result as FmtResult};
 use std::iter::FromIterator;
 use std::ops::Deref;
+use std::ops::DerefMut;
 use std::str::FromStr;
 
 /// The result of a Javascript expression is represented like this so it can succeed (`Ok`) or fail (`Err`)
 pub type ResultValue = Result<Value, Value>;
 /// A Garbage-collected Javascript value as represented in the interpreter
-#[derive(Trace, Finalize, Clone, Debug)]
-pub struct Value {
-    /// The garbage-collected pointer
-    pub ptr: Gc<ValueData>,
-}
+pub type Value = Gc<ValueData>;
 
 /// A Javascript value
 #[derive(Trace, Finalize, Debug)]
@@ -41,7 +38,7 @@ pub enum ValueData {
     Function(GcCell<Function>),
 }
 
-impl Value {
+impl ValueData {
     /// Returns a new empty object
     pub fn new_obj(global: Option<Value>) -> Value {
         let mut obj: ObjectData = HashMap::new();
@@ -50,19 +47,14 @@ impl Value {
                 .unwrap()
                 .get_field_slice("Object")
                 .get_field_slice(PROTOTYPE);
-            obj.insert(
-                INSTANCE_PROTOTYPE.to_string(),
-                Property::from_value(obj_proto),
-            );
-        }
-        Value {
-            ptr: Gc::new(ValueData::Object(GcCell::new(obj))),
+            obj.insert(INSTANCE_PROTOTYPE.to_string(), Property::new(obj_proto));
         }
+        Gc::new(ValueData::Object(GcCell::new(obj)))
     }
 
     /// Returns true if the value is an object
     pub fn is_object(&self) -> bool {
-        match *self.ptr {
+        match *self {
             ValueData::Object(_) => true,
             _ => false,
         }
@@ -70,7 +62,7 @@ impl Value {
 
     /// Returns true if the value is undefined
     pub fn is_undefined(&self) -> bool {
-        match *self.ptr {
+        match *self {
             ValueData::Undefined => true,
             _ => false,
         }
@@ -78,7 +70,7 @@ impl Value {
 
     /// Returns true if the value is null
     pub fn is_null(&self) -> bool {
-        match *self.ptr {
+        match *self {
             ValueData::Null => true,
             _ => false,
         }
@@ -86,7 +78,7 @@ impl Value {
 
     /// Returns true if the value is null or undefined
     pub fn is_null_or_undefined(&self) -> bool {
-        match *self.ptr {
+        match *self {
             ValueData::Null | ValueData::Undefined => true,
             _ => false,
         }
@@ -94,7 +86,7 @@ impl Value {
 
     /// Returns true if the value is a 64-bit floating-point number
     pub fn is_double(&self) -> bool {
-        match *self.ptr {
+        match *self {
             ValueData::Number(_) => true,
             _ => false,
         }
@@ -102,7 +94,7 @@ impl Value {
 
     /// Returns true if the value is a string
     pub fn is_string(&self) -> bool {
-        match *self.ptr {
+        match *self {
             ValueData::String(_) => true,
             _ => false,
         }
@@ -111,7 +103,7 @@ impl Value {
     /// Returns true if the value is true
     /// [toBoolean](https://tc39.github.io/ecma262/#sec-toboolean)
     pub fn is_true(&self) -> bool {
-        match *self.ptr {
+        match *self {
             ValueData::Object(_) => true,
             ValueData::String(ref s) if !s.is_empty() => true,
             ValueData::Number(n) if n >= 1.0 && n % 1.0 == 0.0 => true,
@@ -123,7 +115,7 @@ impl Value {
 
     /// Converts the value into a 64-bit floating point number
     pub fn to_num(&self) -> f64 {
-        match *self.ptr {
+        match *self {
             ValueData::Object(_) | ValueData::Undefined | ValueData::Function(_) => NAN,
             ValueData::String(ref str) => match FromStr::from_str(str) {
                 Ok(num) => num,
@@ -138,7 +130,7 @@ impl Value {
 
     /// Converts the value into a 32-bit integer
     pub fn to_int(&self) -> i32 {
-        match *self.ptr {
+        match *self {
             ValueData::Object(_)
             | ValueData::Undefined
             | ValueData::Null
@@ -157,7 +149,7 @@ impl Value {
     /// Resolve the property in the object
     /// Returns a copy of the Property
     pub fn get_prop(&self, field: String) -> Option<Property> {
-        let obj: ObjectData = match *self.ptr {
+        let obj: ObjectData = match *self {
             ValueData::Object(ref obj) => {
                 let hash = obj.clone();
                 hash.into_inner()
@@ -179,9 +171,7 @@ impl Value {
     pub fn get_field(&self, field: String) -> Value {
         match self.get_prop(field) {
             Some(prop) => prop.value.clone(),
-            None => Value {
-                ptr: Gc::new(ValueData::Undefined),
-            },
+            None => Gc::new(ValueData::Undefined),
         }
     }
 
@@ -192,15 +182,20 @@ impl Value {
 
     /// Set the field in the value
     pub fn set_field(&self, field: String, val: Value) -> Value {
-        match *self.ptr {
+        match *self {
             ValueData::Object(ref obj) => {
                 obj.borrow_mut()
-                    .insert(field.clone(), Property::from_value(val.clone()));
+                    .insert(field.clone(), Property::new(val.clone()));
             }
             ValueData::Function(ref func) => {
-                func.borrow_mut()
-                    .object
-                    .insert(field.clone(), Property::from_value(val.clone()));
+                match *func.borrow_mut().deref_mut() {
+                    Function::NativeFunc(ref mut f) => {
+                        f.object.insert(field.clone(), Property::new(val))
+                    }
+                    Function::RegularFunc(ref mut f) => {
+                        f.object.insert(field.clone(), Property::new(val))
+                    }
+                };
             }
             _ => (),
         }
@@ -214,18 +209,26 @@ impl Value {
 
     /// Set the property in the value
     pub fn set_prop(&self, field: String, prop: Property) -> Property {
-        match *self.ptr {
+        match *self {
             ValueData::Object(ref obj) => {
-                obj.borrow_mut().insert(field.clone(), prop.clone());
+                obj.borrow_mut().insert(field.clone(), prop);
             }
             ValueData::Function(ref func) => {
-                func.borrow_mut().object.insert(field.clone(), prop.clone());
+                match *func.borrow_mut().deref_mut() {
+                    Function::NativeFunc(ref mut f) => f.object.insert(field.clone(), prop),
+                    Function::RegularFunc(ref mut f) => f.object.insert(field.clone(), prop),
+                };
             }
             _ => (),
         }
         prop
     }
 
+    /// Set the property in the value
+    pub fn set_prop_slice<'t>(&self, field: &'t str, prop: Property) -> Property {
+        self.set_prop(field.to_string(), prop)
+    }
+
     /// Convert from a JSON value to a JS value
     pub fn from_json(json: JSONValue) -> ValueData {
         match json {
@@ -238,19 +241,20 @@ impl Value {
                     i += 1;
                     (
                         (i - 1).to_string().to_string(),
-                        Property::from_value(to_value(json.clone())),
+                        Property::new(to_value(json.clone())),
                     )
                 }));
                 data.insert(
                     "length".to_string(),
-                    Property::from_value(to_value(vs.len() as i32)),
+                    Property::new(to_value(vs.len() as i32)),
                 );
                 ValueData::Object(GcCell::new(data))
             }
             JSONValue::Object(obj) => {
-                let data: ObjectData = FromIterator::from_iter(obj.iter().map(|(key, json)| {
-                    (key.clone(), Property::from_value(to_value(json.clone())))
-                }));
+                let data: ObjectData = FromIterator::from_iter(
+                    obj.iter()
+                        .map(|(key, json)| (key.clone(), Property::new(to_value(json.clone())))),
+                );
                 ValueData::Object(GcCell::new(data))
             }
             JSONValue::Null => ValueData::Null,
@@ -258,7 +262,7 @@ impl Value {
     }
 
     pub fn to_json(&self) -> JSONValue {
-        match *self.ptr {
+        match *self {
             ValueData::Null | ValueData::Undefined => JSONValue::Null,
             ValueData::Boolean(b) => JSONValue::Bool(b),
             ValueData::Object(ref obj) => {
@@ -279,7 +283,7 @@ impl Value {
 
     /// Get the type of the value
     pub fn get_type(&self) -> &'static str {
-        match *self.ptr {
+        match *self {
             ValueData::Number(_) | ValueData::Integer(_) => "number",
             ValueData::String(_) => "string",
             ValueData::Boolean(_) => "boolean",
@@ -288,17 +292,11 @@ impl Value {
             _ => "object",
         }
     }
-    /// Get the value for undefined
-    pub fn undefined() -> Value {
-        Value {
-            ptr: Gc::new(ValueData::Undefined),
-        }
-    }
 }
 
-impl Display for Value {
+impl Display for ValueData {
     fn fmt(&self, f: &mut Formatter) -> FmtResult {
-        match *self.ptr {
+        match *self {
             ValueData::Null => write!(f, "null"),
             ValueData::Undefined => write!(f, "undefined"),
             ValueData::Boolean(v) => write!(f, "{}", v),
@@ -337,7 +335,7 @@ impl Display for Value {
 
 impl PartialEq for Value {
     fn eq(&self, other: &Value) -> bool {
-        match (self.ptr.clone().deref(), other.ptr.clone().deref()) {
+        match (self.clone().deref(), other.clone().deref()) {
             // TODO: fix this
             // _ if self.ptr.to_inner() == &other.ptr.to_inner() => true,
             _ if self.is_null_or_undefined() && other.is_null_or_undefined() => true,
@@ -373,9 +371,7 @@ pub trait FromValue {
 
 impl ToValue for String {
     fn to_value(&self) -> Value {
-        Value {
-            ptr: Gc::new(ValueData::String(self.clone())),
-        }
+        Gc::new(ValueData::String(self.clone())),
     }
 }
 
@@ -450,7 +446,7 @@ impl<'s, T: ToValue> ToValue for &'s [T] {
         let mut arr = HashMap::new();
         let mut i = 0;
         for item in self.iter() {
-            arr.insert(i.to_string(), Property::from_value(item.to_value()));
+            arr.insert(i.to_string(), Property::new(item.to_value()));
             i += 1;
         }
         to_value(arr)
@@ -461,7 +457,7 @@ impl<T: ToValue> ToValue for Vec<T> {
         let mut arr = HashMap::new();
         let mut i = 0;
         for item in self.iter() {
-            arr.insert(i.to_string(), Property::from_value(item.to_value()));
+            arr.insert(i.to_string(), Property::new(item.to_value()));
             i += 1;
         }
         to_value(arr)
diff --git a/src/lib/lib.rs b/src/lib/lib.rs
index e00417dc90..f93c8b94d0 100644
--- a/src/lib/lib.rs
+++ b/src/lib/lib.rs
@@ -6,6 +6,6 @@ extern crate time;
 #[macro_use]
 extern crate gc_derive;
 
-// pub mod exec;
+pub mod exec;
 pub mod js;
 pub mod syntax;
diff --git a/src/lib/syntax/ast/expr.rs b/src/lib/syntax/ast/expr.rs
index 53fce62f3b..e686cdd480 100644
--- a/src/lib/syntax/ast/expr.rs
+++ b/src/lib/syntax/ast/expr.rs
@@ -3,7 +3,7 @@ use std::fmt::{Display, Formatter, Result};
 use syntax::ast::constant::Const;
 use syntax::ast::op::{BinOp, Operator, UnaryOp};
 
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, Trace, Debug, PartialEq)]
 pub struct Expr {
     /// The expression definition
     pub def: ExprDef,
@@ -12,9 +12,7 @@ pub struct Expr {
 impl Expr {
     /// Create a new expression with a starting and ending position
     pub fn new(def: ExprDef) -> Expr {
-        Expr {
-            def: def,
-        }
+        Expr { def: def }
     }
 }