diff --git a/version2.0/nasal_gc.h b/version2.0/nasal_gc.h
index e8a4cac..4f621e2 100644
--- a/version2.0/nasal_gc.h
+++ b/version2.0/nasal_gc.h
@@ -35,13 +35,16 @@ class nasal_scalar
 		void   set_string(std::string&);
 		void   vector_push(int);
 		int    vector_pop();
+		int    vector_get_member(int);
 		void   hash_add_new_member(std::string,int);
 		void   hash_delete_member(std::string);
 		int    hash_get_member(std::string);
-		int    get_type();
-		double get_number();
-		std::string     get_string();
-		nasal_function& get_function();
+		int                        get_type();
+		double                     get_number();
+		std::string                get_string();
+		std::vector<int>&          get_vector();
+		std::map<std::string,int>& get_hash();
+		nasal_function&            get_function();
 };
 
 struct gc_unit
@@ -105,22 +108,6 @@ class gc_manager
 			free_space.clear();
 			return;
 		}
-		void gc_scanner()
-		{
-			int memory_size=memory.size();
-			for(int i=0;i<memory_size;++i)
-				if((memory[i].refcnt<=0) && (!memory[i].collected))
-				{
-					// need more details here
-					// especially vector and hash
-					memory[i].set_clear();
-					free_space.push_back(i);
-					std::cout<<">> [Gc] collected ";
-					prt_hex(i);
-					std::cout<<"."<<std::endl;
-				}
-			return;
-		}
 		int gc_alloc()
 		{
 			if(free_space.empty())
@@ -156,7 +143,35 @@ class gc_manager
 		void reference_delete(const int place)
 		{
 			if(place<memory.size())
+			{
 				--memory[place].refcnt;
+				if(!memory[place].refcnt)
+				{
+					memory[place].collected=true;
+					if(memory[place].elem.get_type()==scalar_vector)
+					{
+						int vec_size=memory[place].elem.get_vector().size();
+						for(int i=0;i<vec_size;++i)
+							reference_delete(memory[place].elem.get_vector()[i]);
+					}
+					else if(memory[place].elem.get_type()==scalar_hash)
+					{
+						std::map<std::string,int>::iterator begin_node=memory[place].elem.get_hash().begin();
+						std::map<std::string,int>::iterator end_node=memory[place].elem.get_hash().end();
+						for(std::map<std::string,int>::iterator iter=begin_node;iter!=end_node;++iter)
+							reference_delete(iter->second);
+					}
+					else if(memory[place].elem.get_type()==scalar_function)
+					{
+						std::list<std::map<std::string,int> >::iterator begin_scope=memory[place].elem.get_function().get_local_scope().begin();
+						std::list<std::map<std::string,int> >::iterator end_scope=memory[place].elem.get_function().get_local_scope().end();
+						for(std::list<std::map<std::string,int> >::iterator scope_iter=begin_scope;scope_iter!=end_scope;++scope_iter)
+							for(std::map<std::string,int>::iterator i=scope_iter->begin();i!=scope_iter->end();++i)
+								reference_delete(i->second);
+					}
+					memory[place].elem.set_clear();
+				}
+			}
 			else
 			{
 				std::cout<<">> [Gc] fatal error: unexpected memory place ";
@@ -264,7 +279,8 @@ void nasal_scalar::set_clear()
 	type=scalar_nil;
 	var_string.clear();
 	var_number=0;
-	var_array.clear();
+	std::vector<int> tmp_vec;
+	var_array.swap(tmp_vec);
 	var_hash.clear();
 	var_func.set_clear();
 	return;
@@ -296,6 +312,12 @@ int nasal_scalar::vector_pop()
 	var_array.pop_back();
 	return ret;
 }
+int nasal_scalar::vector_get_member(int place)
+{
+	if(place<0 || place>=var_array.size())
+		return -1;
+	return var_array[place];
+}
 void nasal_scalar::hash_add_new_member(std::string member_name,int addr)
 {
 	// if hash has a new function member
@@ -334,6 +356,14 @@ std::string nasal_scalar::get_string()
 {
 	return var_string;
 }
+std::vector<int>& nasal_scalar::get_vector()
+{
+	return var_array;
+}
+std::map<std::string,int>& nasal_scalar::get_hash()
+{
+	return var_hash;
+}
 nasal_function& nasal_scalar::get_function()
 {
 	return var_func;
diff --git a/version2.0/nasal_runtime.h b/version2.0/nasal_runtime.h
index 309b24f..53a5776 100644
--- a/version2.0/nasal_runtime.h
+++ b/version2.0/nasal_runtime.h
@@ -4,8 +4,11 @@
 class nasal_runtime
 {
     private:
-        // local hash_map will be used when running
-        std::list<std::map<std::string,int> > global_scope;
+        // global scope is a hash_map
+        // null_local_scope is used when function need reference of local scope
+        // but this function is called from global scope
+        std::map<std::string,int> global_scope;
+        std::list<std::map<std::string,int> > null_local_scope;
         
         // see detail of each enum type in function error_interrupt(const int)
         enum runtime_error_type
@@ -17,10 +20,10 @@ class nasal_runtime
         void error_interrupt   (const int);
         void vector_generation (abstract_syntax_tree&);
         void hash_generation   (abstract_syntax_tree&);
-        void call_identifier   (abstract_syntax_tree&);
         void calculation       (abstract_syntax_tree&);
-        void assignment        (abstract_syntax_tree&);
-        void definition        (abstract_syntax_tree&);
+        void call_identifier   (std::list<std::map<std::string,int> >&,abstract_syntax_tree&);
+        void assignment        (std::list<std::map<std::string,int> >&,abstract_syntax_tree&);
+        void definition        (std::list<std::map<std::string,int> >&,abstract_syntax_tree&);
         void loop_expr         (abstract_syntax_tree&);
         void conditional       (abstract_syntax_tree&);
         void func_proc         (std::list<std::map<std::string,int> >&,abstract_syntax_tree&);
@@ -64,28 +67,42 @@ void nasal_runtime::hash_generation(abstract_syntax_tree& node)
 {
     return;
 }
-void nasal_runtime::call_identifier(abstract_syntax_tree& node)
-{
-    return;
-}
 void nasal_runtime::calculation(abstract_syntax_tree& node)
 {
     return;
 }
-void nasal_runtime::assignment(abstract_syntax_tree& node)
+void nasal_runtime::call_identifier(std::list<std::map<std::string,int> >& local_scope,abstract_syntax_tree& node)
 {
+    if(local_scope.empty())
+        ;
     return;
 }
-void nasal_runtime::definition(abstract_syntax_tree& node)
+void nasal_runtime::assignment(std::list<std::map<std::string,int> >& local_scope,abstract_syntax_tree& node)
 {
+    if(local_scope.empty())
+        ;
+    return;
+}
+void nasal_runtime::definition(std::list<std::map<std::string,int> >& local_scope,abstract_syntax_tree& node)
+{
+    if(local_scope.empty())
+        ;
     return;
 }
 void nasal_runtime::loop_expr(abstract_syntax_tree& node)
 {
+    std::list<std::map<std::string,int> > local_scope;
+    std::map<std::string,int> new_scope;
+    local_scope.push_back(new_scope);
+
     return;
 }
 void nasal_runtime::conditional(abstract_syntax_tree& node)
 {
+    std::list<std::map<std::string,int> > local_scope;
+    std::map<std::string,int> new_scope;
+    local_scope.push_back(new_scope);
+    
     return;
 }
 
@@ -104,7 +121,7 @@ void nasal_runtime::func_proc(std::list<std::map<std::string,int> >& local_scope
             ;
         // only number or string
         else if(node_type==__id)
-            this->call_identifier(*iter);
+            this->call_identifier(local_scope,*iter);
         else if(node_type==__vector)
             this->vector_generation(*iter);
         else if(node_type==__hash)
@@ -150,7 +167,7 @@ void nasal_runtime::main_proc(abstract_syntax_tree& root)
         if(node_type==__number || node_type==__string)
             ;
         else if(node_type==__id)
-            this->call_identifier(*iter);
+            this->call_identifier(null_local_scope,*iter);
         else if(node_type==__vector)
             this->vector_generation(*iter);
         else if(node_type==__hash)