//todo working on scope for better emit
        public System.Delegate Compile(System.Type target, IExpressionVisitor <object> visitor)
        {
            //pass scoped arguments // refer System.Linq.Expression.Compiler folder
            var context = TypeContext.Default;

            System.Type returnType;
            if (ReturnSyntax != null)
            {
                returnType = ReturnSyntax.ResolveType(context);
            }
            else
            {
                returnType = TypeProvider.AnyType;
            }
            var names  = Parameters.Map(para => para.Name).AddFirst("closure");
            int length = Parameters.Count;

            System.Type[] types      = new System.Type[length];
            var           parameters = new ParameterInfo[length];

            for (int i = 0; i < Parameters.Count; i++)
            {
                var         para = Parameters[i];
                System.Type type = para.Type == null ? TypeProvider.AnyType : para.Type.ResolveType(context);
                parameters[i] = new ParameterInfo(para.Name, i + 1, type, para.IsVarArgs);
                types[i]      = type;
            }
            // Emit First Argument
            var lamdaVisit = new LamdaVisitor(names);

            Body.Accept(lamdaVisit);
            var parameterTypes = types.AddFirst(typeof(Closure));
            var method         = new System.Reflection.Emit.DynamicMethod("lambda_method", returnType, parameterTypes, true);

            var methodGen = new Generators.DynamicMethodGenerator(method, parameters, target)
            {
                SyntaxBody = Body,
                Context    = context
            };

            methodGen.EmitParameterInfo();
            var bodyGen = new MethodBodyGenerator(methodGen, method.GetILGenerator());

            object[] values = new object[lamdaVisit.HoistedLocals.Count];
            if (values.Length > 0)
            {
                int index = 0;
                var field = typeof(Closure).GetField("Values");
                foreach (var item in lamdaVisit.HoistedLocals)
                {
                    var value = item.Value;
                    values[index] = value.Accept(visitor);
                    var variable = bodyGen.DeclareVariable(value.Type, item.Key);
                    bodyGen.LoadArgument(0);
                    bodyGen.LoadField(field);
                    bodyGen.LoadInt32(index);
                    bodyGen.LoadArrayElement(typeof(object));
                    bodyGen.UnboxObject(value.Type);
                    bodyGen.StoreVariable(variable);
                    index++;
                }
            }
            bodyGen.Compile();
            var delgateType = DelegateGen.MakeNewDelegate(types, returnType);

            Type = delgateType;
            return(method.CreateDelegate(delgateType, new Runtime.Closure(values)));
        }