diff --git a/README.md b/README.md
index cbb0ae6..371903c 100644
--- a/README.md
+++ b/README.md
@@ -213,6 +213,22 @@ __`vm_str`__ has 3 formats. The third one is used to declare a character.
 var s='str';
 var s="another string";
 var s=`c`;
+
+# some special characters is allowed in this language:
+
+'\a';
+'\b';
+'\e';
+'\f';
+'\n';
+'\r';
+'\t';
+'\v';
+'\0';
+'\\';
+'\?';
+'\'';
+'\"';
 ```
 
 __`vm_vec`__ has unlimited length and can store all types of values.
diff --git a/makefile b/makefile
index a9a5c44..ec37858 100644
--- a/makefile
+++ b/makefile
@@ -31,5 +31,5 @@ test:nasal
 	./nasal -op -e test/scalar.nas
 	./nasal -op -e test/trait.nas
 	./nasal -op -t -d test/turingmachine.nas
-	./nasal -op -t -d test/ycombinator.nas
+	./nasal -op -t -d -o test/ycombinator.nas
 	
\ No newline at end of file
diff --git a/nasal_builtin.h b/nasal_builtin.h
index 8617f63..0ec9666 100644
--- a/nasal_builtin.h
+++ b/nasal_builtin.h
@@ -949,7 +949,7 @@ nasal_ref builtin_opendir(nasal_ref* local,nasal_gc& gc)
         return builtin_err("opendir","\"path\" must be string");
     DIR* p=opendir(path.str()->c_str());
     if(!p)
-        return builtin_err("opendir","cannot open dir <"+*path.str()+">");
+        return builtin_err("opendir","cannot open dir <"+*path.str()+"> errno "+std::to_string(errno));
     nasal_ref ret=gc.alloc(vm_obj);
     ret.obj()->type=obj_dir;
     ret.obj()->ptr=(void*)p;
@@ -1020,7 +1020,7 @@ nasal_ref builtin_dlopen(nasal_ref* local,nasal_gc& gc)
     void* ptr=dlopen(dlname.str()->c_str(),RTLD_LOCAL|RTLD_LAZY);
 #endif
     if(!ptr)
-        return builtin_err("dlopen","cannot open dynamic lib \""+*dlname.str()+"\"");
+        return builtin_err("dlopen","cannot open dynamic lib <"+*dlname.str()+">");
     nasal_ref ret=gc.alloc(vm_obj);
     ret.obj()->type=obj_dylib;
     ret.obj()->ptr=ptr;
diff --git a/test/turingmachine.nas b/test/turingmachine.nas
index 86e6a13..5c65025 100644
--- a/test/turingmachine.nas
+++ b/test/turingmachine.nas
@@ -7,8 +7,44 @@ var table=[
     ['q2','0','1','R','q3'],
     ['q3',nil,nil,'S','q3']
 ];
+
+var operand={
+    new:func(symbol,changed_symbol,move,next_state){
+        if(move!='L' and move!='R' and move!='S')
+            die("invalid move type:"+move);
+        return {
+            symbol:symbol,
+            changed_symbol:changed_symbol,
+            move:move,
+            next_state:next_state
+        };
+    }
+};
+
+var machine={
+    states:{},
+    add:func(state,operand){
+        if(!contains(me.states,state))
+            me.states[state]=[operand];
+        else{
+            foreach(var i;me.states[state])
+                if(i.symbol==operand.symbol or i.symbol==nil){
+                    println(i);
+                    die("conflict operand");
+                }
+            append(me.states[state],operand);
+        }
+    },
+    load:func(data){
+        foreach(var opr;data){
+            var (nstat,sym,csym,move,nextstat)=opr;
+            me.add(nstat,operand.new(sym,csym,move,nextstat));
+        }
+    }
+};
+
 var prt=func(state,pointer,paper,act=nil){
-    print(state,':',pointer,':',act!=nil?act:'','\n\t');
+    print(act!=nil?act:'','\n\t');
     var s='';
     foreach(var i;paper)
         s~=i;
@@ -16,37 +52,50 @@ var prt=func(state,pointer,paper,act=nil){
     for(var i=0;i<pointer;i+=1)
         for(var j=0;j<size(paper[i]);j+=1)
             s~=' ';
-    print(s,'^\n');
+    print(s,'^\n',state," ");
 }
-var run=func(table,node,start,stop){
+var run=func(table,start,stop){
     var paper=['0','1','1','1','0','1','0','a'];
     var pointer=0;
-    foreach(var action;table){
-        if(!contains(node,action[0]))
-            node[action[0]]=nil;
-        if(!contains(node,action[4]))
-            node[action[4]]=nil;
-        print(action,'\n');
-    }
-    print("nodes: ",keys(node),'\n');
-    if(!contains(node,start))
+
+    machine.load(table);
+
+    print("states: ",keys(machine.states),'\n');
+    if(!contains(machine.states,start))
         die(start~" is not a valid node");
-    if(!contains(node,stop))
+    if(!contains(machine.states,stop))
         die(stop~" is not a valid node");
-    var state=start;
+    
+    var (state,pointer)=(start,0);
+
     prt(state,pointer,paper);
     while(state!=stop){
-        foreach(var action;table)
-            if(action[0]==state and (action[1]==paper[pointer] or action[1]==' ')){
-                paper[pointer]=action[2]==nil?paper[pointer]:action[2];
-                if(action[3]=='L') pointer-=1;
-                elsif(action[3]=='R') pointer+=1;
-                elsif(action[3]!='S') die("invalid action <"~action[3]~'>');
-                state=action[4];
+        if(!contains(machine.states,state))
+            die("no matching function for state:"~state);
+        var found=0;
+        foreach(var action;machine.states[state]){
+            var (sym,csym,move,next)=(
+                action.symbol,
+                action.changed_symbol,
+                action.move,
+                action.next_state
+            );
+            if(sym==paper[pointer] or sym==nil){
+                if(sym!=nil)
+                    paper[pointer]=csym;
+                if(move=='L') pointer-=1;
+                elsif(move=='R') pointer+=1;
+                (state,found)=(next,1);
                 break;
             }
-        prt(state,pointer,paper,action);
+        }
+
+        if(!found)
+            die("no matching function for state:"~state);
+
+        prt(state,pointer,paper,[sym,csym,move,next]);
     }
 }
 
-run(table,{},'q0','q3');
\ No newline at end of file
+run(table,'q0','q3');
+print('\n');
\ No newline at end of file