diff --git a/main.cpp b/main.cpp
index 860058e..8f21d52 100644
--- a/main.cpp
+++ b/main.cpp
@@ -46,6 +46,7 @@ void logo()
 void die(const char* stage,std::string& filename)
 {
     std::cout<<"["<<stage<<"] in <"<<filename<<">: error(s) occurred,stop.\n";
+    exit(1);
     return;
 }
 
@@ -59,10 +60,7 @@ void execute(std::string& file,std::string& command)
     lexer.openfile(file);
     lexer.scanner();
     if(lexer.get_error())
-    {
         die("lexer",file);
-        return;
-    }
     if(command=="--lex" || command=="-l")
     {
         lexer.print_token();
@@ -70,10 +68,7 @@ void execute(std::string& file,std::string& command)
     }
     parse.main_process(lexer.get_token_list());
     if(parse.get_error())
-    {
         die("parse",file);
-        return;
-    }
     if(command=="--ast" || command=="-a")
     {
         parse.get_root().print_ast(0);
@@ -82,16 +77,10 @@ void execute(std::string& file,std::string& command)
     // first used file is itself
     import.link(parse.get_root(),file);
     if(import.get_error())
-    {
         die("import",file);
-        return;
-    }
     codegen.main_progress(import.get_root(),import.get_file());
     if(codegen.get_error())
-    {
         die("code",file);
-        return;
-    }
     if(command=="--code" || command=="-c")
     {
         codegen.print_byte_code();
@@ -149,6 +138,7 @@ int main(int argc,const char* argv[])
         std::cout
         <<"invalid argument(s).\n"
         <<"use nasal -h to get help.\n";
+        exit(1);
     }
     return 0;
 }
\ No newline at end of file
diff --git a/test/trait.nas b/test/trait.nas
new file mode 100644
index 0000000..0f00688
--- /dev/null
+++ b/test/trait.nas
@@ -0,0 +1,39 @@
+import("lib.nas");
+
+var trait={
+    get:func{return me.val;},
+    set:func(x){me.val=x;}
+};
+
+var class={
+    new:func(){
+        return {
+            val:nil,
+            parents:[trait]
+        };
+    }
+};
+
+var class2={
+    new:func(){
+        return {
+            val:nil,
+            parents:[trait],
+            set:func(x){me.val=typeof(x);}
+        };
+    }
+};
+
+var class_obj=[];
+for(var i=0;i<10;i+=1){
+    append(class_obj,class.new());
+    class_obj[i].set(i);
+}
+for(var i=0;i<10;i+=1){
+    append(class_obj,class2.new());
+    class_obj[10+i].set(i);
+}
+
+foreach(var object;class_obj){
+    println(object.get(),' ',keys(object));
+}
\ No newline at end of file