diff --git a/nasal.h b/nasal.h
index d4c76fe..dd8bb7e 100644
--- a/nasal.h
+++ b/nasal.h
@@ -23,7 +23,7 @@ using std::string;
 
 const u32 STACK_DEPTH=1024;
 
-inline f64 hex2f(const char* str) {
+f64 hex2f(const char* str) {
     f64 ret=0;
     for(;*str;++str) {
         if ('0'<=*str && *str<='9') {
@@ -39,7 +39,7 @@ inline f64 hex2f(const char* str) {
     return ret;
 }
 
-inline f64 oct2f(const char* str) {
+f64 oct2f(const char* str) {
     f64 ret=0;
     while('0'<=*str && *str<'8') {
         ret=ret*8+(*str++-'0');
@@ -54,7 +54,7 @@ inline f64 oct2f(const char* str) {
 // it is not platform independent, and may have strange output.
 // so we write a new function here to convert str to number manually.
 // but this also makes 0.1+0.2==0.3, not another result that you may get in other languages.
-inline f64 dec2f(const char* str) {
+f64 dec2f(const char* str) {
     f64 ret=0,negative=1,num_pow=0;
     while('0'<=*str && *str<='9') {
         ret=ret*10+(*str++-'0');
diff --git a/nasal_ast.h b/nasal_ast.h
index 518abea..8924745 100644
--- a/nasal_ast.h
+++ b/nasal_ast.h
@@ -157,13 +157,13 @@ public:
     void set_str(const string& s) {nd_str=s;}
     void set_num(const f64 n) {nd_num=n;}
 
-    inline u32 line() const {return nd_line;}
-    inline u32 col()  const {return nd_col;}
-    inline u32 type() const {return nd_type;}
-    inline f64 num()  const {return nd_num;}
-    inline const string& str() const {return nd_str;}
-    inline const std::vector<ast>& child() const {return nd_child;}
-    inline std::vector<ast>& child() {return nd_child;}
+    u32 line() const {return nd_line;}
+    u32 col()  const {return nd_col;}
+    u32 type() const {return nd_type;}
+    f64 num()  const {return nd_num;}
+    const string& str() const {return nd_str;}
+    const std::vector<ast>& child() const {return nd_child;}
+    std::vector<ast>& child() {return nd_child;}
 };
 
 ast::ast(const ast& tmp):
diff --git a/nasal_builtin.h b/nasal_builtin.h
index 5f4350c..bc0bdcb 100644
--- a/nasal_builtin.h
+++ b/nasal_builtin.h
@@ -1151,13 +1151,20 @@ var builtin_coresume(var* local,gc& ngc) {
         return nas_err("coroutine::resume","cannot start another coroutine when one is running");
     }
     var co=local[1];
+    // return nil if is not a coroutine object
     if (co.type!=vm_co) {
-        return nas_err("coroutine::resume","must use a coroutine object");
+        return nil;
     }
+    // cannot resume a dead coroutine
     if (co.co().status==nas_co::dead) {
         return nil;
     }
+
+    // change to coroutine context
     ngc.ctxchg(co.co());
+
+    // fetch coroutine's stack top and return
+    // so the coroutine's stack top in fact is not changed
     return ngc.top[0];
 }
 
@@ -1165,16 +1172,21 @@ var builtin_coyield(var* local,gc& ngc) {
     if (!ngc.cort) {
         return nas_err("coroutine::yield","no coroutine is running");
     }
-    ngc.ctxreserve();
+
     // this will set to main stack top
-    // then builtin_coresume will return it
+    ngc.ctxreserve();
+    
+    // then this will return value to main's stack top[0]
+    // the procedure seems like coroutine.resume returns the value
+    // but in fact coroutine.resume stop the main context
+    // until coroutine calls the coroutine.yield
     return local[1];
 }
 
 var builtin_costatus(var* local,gc& ngc) {
     var co=local[1];
     if (co.type!=vm_co) {
-        return nas_err("coroutine::status","must use a coroutine object");
+        return ngc.newstr("error");
     }
     switch(co.co().status) {
         case nas_co::suspended: return ngc.newstr("suspended");break;
diff --git a/nasal_gc.h b/nasal_gc.h
index d36d8b7..823de2e 100644
--- a/nasal_gc.h
+++ b/nasal_gc.h
@@ -80,17 +80,17 @@ struct var {
     string tostr();
     friend std::ostream& operator<<(std::ostream&,var&);
     bool   objchk(u32);
-    inline var*       addr();
-    inline u32        ret ();
-    inline i64&       cnt ();
-    inline f64        num ();
-    inline string&    str ();
-    inline nas_vec&   vec ();
-    inline nas_hash&  hash();
-    inline nas_func&  func();
-    inline nas_upval& upval();
-    inline nas_obj&   obj ();
-    inline nas_co&    co  ();
+    var*       addr();
+    u32        ret ();
+    i64&       cnt ();
+    f64        num ();
+    string&    str ();
+    nas_vec&   vec ();
+    nas_hash&  hash();
+    nas_func&  func();
+    nas_upval& upval();
+    nas_obj&   obj ();
+    nas_co&    co  ();
 };
 
 struct nas_vec {
@@ -412,17 +412,17 @@ bool var::objchk(u32 objtype) {
     return type==vm_obj && obj().type==objtype && obj().ptr;
 }
 
-inline var*       var::addr () {return val.addr;             }
-inline u32        var::ret  () {return val.ret;              }
-inline i64&       var::cnt  () {return val.cnt;              }
-inline f64        var::num  () {return val.num;              }
-inline string&    var::str  () {return *val.gcobj->ptr.str;  }
-inline nas_vec&   var::vec  () {return *val.gcobj->ptr.vec;  }
-inline nas_hash&  var::hash () {return *val.gcobj->ptr.hash; }
-inline nas_func&  var::func () {return *val.gcobj->ptr.func; }
-inline nas_upval& var::upval() {return *val.gcobj->ptr.upval;}
-inline nas_obj&   var::obj  () {return *val.gcobj->ptr.obj;  }
-inline nas_co&    var::co   () {return *val.gcobj->ptr.co;   }
+var*       var::addr () {return val.addr;             }
+u32        var::ret  () {return val.ret;              }
+i64&       var::cnt  () {return val.cnt;              }
+f64        var::num  () {return val.num;              }
+string&    var::str  () {return *val.gcobj->ptr.str;  }
+nas_vec&   var::vec  () {return *val.gcobj->ptr.vec;  }
+nas_hash&  var::hash () {return *val.gcobj->ptr.hash; }
+nas_func&  var::func () {return *val.gcobj->ptr.func; }
+nas_upval& var::upval() {return *val.gcobj->ptr.upval;}
+nas_obj&   var::obj  () {return *val.gcobj->ptr.obj;  }
+nas_co&    var::co   () {return *val.gcobj->ptr.co;   }
 
 const var zero={vm_num,(f64)0};
 const var one ={vm_num,(f64)1};
diff --git a/nasal_lexer.h b/nasal_lexer.h
index d09481b..b75664c 100644
--- a/nasal_lexer.h
+++ b/nasal_lexer.h
@@ -238,28 +238,31 @@ string lexer::utf8_gen() {
     while(ptr<res.size() && res[ptr]<0) {
         string tmp="";
         u32 nbytes=utf8_hdchk(res[ptr]);
-        if (nbytes) {
-            tmp+=res[ptr++];
-            for(u32 i=0;i<nbytes;++i,++ptr) {
-                if (ptr<res.size() && (res[ptr]&0xc0)==0x80) {
-                    tmp+=res[ptr];
-                }
-            }
-            if (tmp.length()!=1+nbytes) {
-                ++column;
-                string utf_info="0x"+chrhex(tmp[0]);
-                for(u32 i=1;i<tmp.size();++i) {
-                    utf_info+=" 0x"+chrhex(tmp[i]);
-                }
-                err.err("lexer",line,column,1,"invalid utf-8 <"+utf_info+">");
-                err.fatal("lexer","fatal error occurred, stop");
-            }
-            str+=tmp;
-            column+=2; // may have some problems because not all the unicode takes 2 space
-        } else {
+        if (!nbytes) {
             ++ptr;
             ++column;
+            continue;
         }
+
+        tmp+=res[ptr++];
+        for(u32 i=0;i<nbytes;++i,++ptr) {
+            if (ptr<res.size() && (res[ptr]&0xc0)==0x80) {
+                tmp+=res[ptr];
+            }
+        }
+
+        // utf8 character's total length is 1+nbytes
+        if (tmp.length()!=1+nbytes) {
+            ++column;
+            string utf_info="0x"+chrhex(tmp[0]);
+            for(u32 i=1;i<tmp.size();++i) {
+                utf_info+=" 0x"+chrhex(tmp[i]);
+            }
+            err.err("lexer",line,column,1,"invalid utf-8 <"+utf_info+">");
+            err.fatal("lexer","fatal error occurred, stop");
+        }
+        str+=tmp;
+        column+=2; // may have some problems because not all the unicode takes 2 space
     }
     return str;
 }
diff --git a/nasal_vm.h b/nasal_vm.h
index 2aeda98..2e59fb1 100644
--- a/nasal_vm.h
+++ b/nasal_vm.h
@@ -313,12 +313,18 @@ void vm::die(const string& str) {
     std::cout<<"[vm] error: "<<str<<"\n";
     traceback();
     stackinfo();
+
+    // show verbose crash info
     if (verbose) {
         detail();
     }
+
     if (ngc.stack==stack) {
+        // in main context, exit directly
         std::exit(1);
     } else {
+        // in coroutine, shut down the coroutine
+        // and return to main context
         pc=0; // mark coroutine 'dead'
         ngc.ctxreserve();
         top[0]=nil;
@@ -330,48 +336,48 @@ inline bool vm::cond(var& val) {
         return val.num();
     } else if (val.type==vm_str) {
         const f64 num=str2num(val.str().c_str());
-        return std::isnan(num)?!val.str().empty():num;
+        return std::isnan(num)? !val.str().empty():num;
     }
     return false;
 }
 
-inline void vm::o_intg() {
+void vm::o_intg() {
     // global values store on stack
     top+=imm[pc];
     --top;// point to the top
 }
 
-inline void vm::o_intl() {
+void vm::o_intl() {
     top[0].func().local.resize(imm[pc],nil);
     top[0].func().lsize=imm[pc];
 }
 
-inline void vm::o_loadg() {
+void vm::o_loadg() {
     stack[imm[pc]]=(top--)[0];
 }
 
-inline void vm::o_loadl() {
+void vm::o_loadl() {
     localr[imm[pc]]=(top--)[0];
 }
 
-inline void vm::o_loadu() {
+void vm::o_loadu() {
     funcr.func().upval[(imm[pc]>>16)&0xffff]
          .upval()[imm[pc]&0xffff]=(top--)[0];
 }
 
-inline void vm::o_pnum() {
+void vm::o_pnum() {
     (++top)[0]={vm_num,cnum[imm[pc]]};
 }
 
-inline void vm::o_pnil() {
+void vm::o_pnil() {
     (++top)[0]=nil;
 }
 
-inline void vm::o_pstr() {
+void vm::o_pstr() {
     (++top)[0]=ngc.strs[imm[pc]];
 }
 
-inline void vm::o_newv() {
+void vm::o_newv() {
     var newv=ngc.alloc(vm_vec);
     auto& vec=newv.vec().elems;
     vec.resize(imm[pc]);
@@ -383,11 +389,11 @@ inline void vm::o_newv() {
     top[0]=newv;
 }
 
-inline void vm::o_newh() {
+void vm::o_newh() {
     (++top)[0]=ngc.alloc(vm_hash);
 }
 
-inline void vm::o_newf() {
+void vm::o_newf() {
     (++top)[0]=ngc.alloc(vm_func);
     nas_func& func=top[0].func();
     func.entry=imm[pc];
@@ -406,19 +412,19 @@ inline void vm::o_newf() {
     }
 }
 
-inline void vm::o_happ() {
+void vm::o_happ() {
     top[-1].hash().elems[cstr[imm[pc]]]=top[0];
     --top;
 }
 
-inline void vm::o_para() {
+void vm::o_para() {
     nas_func& func=top[0].func();
     // func->size has 1 place reserved for "me"
     func.keys[imm[pc]]=func.psize;
     func.local[func.psize++]={vm_none};
 }
 
-inline void vm::o_deft() {
+void vm::o_deft() {
     var val=top[0];
     nas_func& func=(--top)[0].func();
     // func->size has 1 place reserved for "me"
@@ -426,11 +432,11 @@ inline void vm::o_deft() {
     func.local[func.psize++]=val;
 }
 
-inline void vm::o_dyn() {
+void vm::o_dyn() {
     top[0].func().dpara=imm[pc];
 }
 
-inline void vm::o_unot() {
+void vm::o_unot() {
     var val=top[0];
     switch(val.type) {
         case vm_nil:top[0]=one;break;
@@ -450,7 +456,7 @@ inline void vm::o_unot() {
     }
 }
 
-inline void vm::o_usub() {
+void vm::o_usub() {
     top[0]={vm_num,-top[0].tonum()};
 }
 
@@ -458,11 +464,11 @@ inline void vm::o_usub() {
     top[-1]={vm_num,top[-1].tonum() type top[0].tonum()};\
     --top;
 
-inline void vm::o_add() {op_calc(+);}
-inline void vm::o_sub() {op_calc(-);}
-inline void vm::o_mul() {op_calc(*);}
-inline void vm::o_div() {op_calc(/);}
-inline void vm::o_lnk() {
+void vm::o_add() {op_calc(+);}
+void vm::o_sub() {op_calc(-);}
+void vm::o_mul() {op_calc(*);}
+void vm::o_div() {op_calc(/);}
+void vm::o_lnk() {
     top[-1]=ngc.newstr(top[-1].tostr()+top[0].tostr());
     --top;
 }
@@ -470,11 +476,11 @@ inline void vm::o_lnk() {
 #define op_calc_const(type)\
     top[0]={vm_num,top[0].tonum() type cnum[imm[pc]]};
 
-inline void vm::o_addc() {op_calc_const(+);}
-inline void vm::o_subc() {op_calc_const(-);}
-inline void vm::o_mulc() {op_calc_const(*);}
-inline void vm::o_divc() {op_calc_const(/);}
-inline void vm::o_lnkc() {
+void vm::o_addc() {op_calc_const(+);}
+void vm::o_subc() {op_calc_const(-);}
+void vm::o_mulc() {op_calc_const(*);}
+void vm::o_divc() {op_calc_const(/);}
+void vm::o_lnkc() {
     top[0]=ngc.newstr(top[0].tostr()+cstr[imm[pc]]);
 }
 
@@ -483,11 +489,11 @@ inline void vm::o_lnkc() {
     memr=nullptr;\
     top-=imm[pc]+1;
 
-inline void vm::o_addeq() {op_calc_eq(+);}
-inline void vm::o_subeq() {op_calc_eq(-);}
-inline void vm::o_muleq() {op_calc_eq(*);}
-inline void vm::o_diveq() {op_calc_eq(/);}
-inline void vm::o_lnkeq() {
+void vm::o_addeq() {op_calc_eq(+);}
+void vm::o_subeq() {op_calc_eq(-);}
+void vm::o_muleq() {op_calc_eq(*);}
+void vm::o_diveq() {op_calc_eq(/);}
+void vm::o_lnkeq() {
     top[-1]=memr[0]=ngc.newstr(memr[0].tostr()+top[-1].tostr());
     memr=nullptr;
     top-=imm[pc]+1;
@@ -498,17 +504,17 @@ inline void vm::o_lnkeq() {
     memr=nullptr;\
     top-=(imm[pc]>>31);
 
-inline void vm::o_addeqc() {op_calc_eq_const(+);}
-inline void vm::o_subeqc() {op_calc_eq_const(-);}
-inline void vm::o_muleqc() {op_calc_eq_const(*);}
-inline void vm::o_diveqc() {op_calc_eq_const(/);}
-inline void vm::o_lnkeqc() {
+void vm::o_addeqc() {op_calc_eq_const(+);}
+void vm::o_subeqc() {op_calc_eq_const(-);}
+void vm::o_muleqc() {op_calc_eq_const(*);}
+void vm::o_diveqc() {op_calc_eq_const(/);}
+void vm::o_lnkeqc() {
     top[0]=memr[0]=ngc.newstr(memr[0].tostr()+cstr[imm[pc]&0x7fffffff]);
     memr=nullptr;
     top-=(imm[pc]>>31);
 }
 
-inline void vm::o_meq() {
+void vm::o_meq() {
     // pop old memr[0] and replace it
     // the reason why we should get memr and push the old value on stack
     // is that when lnkeq/lnkeqc is called, there will be
@@ -519,7 +525,7 @@ inline void vm::o_meq() {
     top-=imm[pc]+1;
 }
 
-inline void vm::o_eq() {
+void vm::o_eq() {
     var val2=top[0];
     var val1=(--top)[0];
     if (val1.type==vm_nil && val2.type==vm_nil) {
@@ -534,7 +540,7 @@ inline void vm::o_eq() {
     }
 }
 
-inline void vm::o_neq() {
+void vm::o_neq() {
     var val2=top[0];
     var val1=(--top)[0];
     if (val1.type==vm_nil && val2.type==vm_nil) {
@@ -553,28 +559,28 @@ inline void vm::o_neq() {
     --top;\
     top[0]=(top[0].tonum() type top[1].tonum())?one:zero;
 
-inline void vm::o_less() {op_cmp(<);}
-inline void vm::o_leq() {op_cmp(<=);}
-inline void vm::o_grt() {op_cmp(>);}
-inline void vm::o_geq() {op_cmp(>=);}
+void vm::o_less() {op_cmp(<);}
+void vm::o_leq() {op_cmp(<=);}
+void vm::o_grt() {op_cmp(>);}
+void vm::o_geq() {op_cmp(>=);}
 
 #define op_cmp_const(type)\
     top[0]=(top[0].tonum() type cnum[imm[pc]])?one:zero;
 
-inline void vm::o_lessc() {op_cmp_const(<);}
-inline void vm::o_leqc() {op_cmp_const(<=);}
-inline void vm::o_grtc() {op_cmp_const(>);}
-inline void vm::o_geqc() {op_cmp_const(>=);}
+void vm::o_lessc() {op_cmp_const(<);}
+void vm::o_leqc() {op_cmp_const(<=);}
+void vm::o_grtc() {op_cmp_const(>);}
+void vm::o_geqc() {op_cmp_const(>=);}
 
-inline void vm::o_pop() {
+void vm::o_pop() {
     --top;
 }
 
-inline void vm::o_jmp() {
+void vm::o_jmp() {
     pc=imm[pc]-1;
 }
 
-inline void vm::o_jt() {
+void vm::o_jt() {
     // jump true needs to reserve the result on stack
     // because conditional expression in nasal has return value
     if (cond(top[0])) {
@@ -582,7 +588,7 @@ inline void vm::o_jt() {
     }
 }
 
-inline void vm::o_jf() {
+void vm::o_jf() {
     // jump false doesn't need to reserve result
     if (!cond(top[0])) {
         pc=imm[pc]-1;
@@ -590,7 +596,7 @@ inline void vm::o_jf() {
     --top;
 }
 
-inline void vm::o_cnt() {
+void vm::o_cnt() {
     if (top[0].type!=vm_vec) {
         die("must use vector in forindex/foreach");
         return;
@@ -598,7 +604,7 @@ inline void vm::o_cnt() {
     (++top)[0]={vm_cnt,(i64)-1};
 }
 
-inline void vm::o_findex() {
+void vm::o_findex() {
     if ((usize)(++top[0].cnt())>=top[-1].vec().size()) {
         pc=imm[pc]-1;
         return;
@@ -607,7 +613,7 @@ inline void vm::o_findex() {
     ++top;
 }
 
-inline void vm::o_feach() {
+void vm::o_feach() {
     auto& ref=top[-1].vec().elems;
     if ((usize)(++top[0].cnt())>=ref.size()) {
         pc=imm[pc]-1;
@@ -617,20 +623,20 @@ inline void vm::o_feach() {
     ++top;
 }
 
-inline void vm::o_callg() {
+void vm::o_callg() {
     (++top)[0]=stack[imm[pc]];
 }
 
-inline void vm::o_calll() {
+void vm::o_calll() {
     (++top)[0]=localr[imm[pc]];
 }
 
-inline void vm::o_upval() {
+void vm::o_upval() {
     (++top)[0]=funcr.func().upval[(imm[pc]>>16)&0xffff]
                     .upval()[imm[pc]&0xffff];
 }
 
-inline void vm::o_callv() {
+void vm::o_callv() {
     var val=top[0];
     var vec=(--top)[0];
     if (vec.type==vm_vec) {
@@ -666,7 +672,7 @@ inline void vm::o_callv() {
     }
 }
 
-inline void vm::o_callvi() {
+void vm::o_callvi() {
     var val=top[0];
     if (val.type!=vm_vec) {
         die("must use a vector");
@@ -680,7 +686,7 @@ inline void vm::o_callvi() {
     }
 }
 
-inline void vm::o_callh() {
+void vm::o_callh() {
     var val=top[0];
     if (val.type!=vm_hash) {
         die("must call a hash");
@@ -695,7 +701,7 @@ inline void vm::o_callh() {
     }
 }
 
-inline void vm::o_callfv() {
+void vm::o_callfv() {
     u32 argc=imm[pc]; // arguments counter
     var* local=top-argc+1; // arguments begin address
     if (local[-1].type!=vm_func) {
@@ -753,7 +759,7 @@ inline void vm::o_callfv() {
     upvalr=nil;
 }
 
-inline void vm::o_callfh() {
+void vm::o_callfh() {
     auto& hash=top[0].hash().elems;
     if (top[-1].type!=vm_func) {
         die("must call a function");
@@ -797,7 +803,7 @@ inline void vm::o_callfh() {
     upvalr=nil;
 }
 
-inline void vm::o_callb() {
+void vm::o_callb() {
     // reserve place for builtin function return,
     // in fact this code is changed because of coroutine
     (++top)[0]=nil;
@@ -811,7 +817,7 @@ inline void vm::o_callb() {
     }
 }
 
-inline void vm::o_slcbeg() {
+void vm::o_slcbeg() {
     // +--------------+
     // | slice_vector | <-- top[0]
     // +--------------+
@@ -824,12 +830,12 @@ inline void vm::o_slcbeg() {
     }
 }
 
-inline void vm::o_slcend() {
+void vm::o_slcend() {
     top[-1]=top[0];
     --top;
 }
 
-inline void vm::o_slc() {
+void vm::o_slc() {
     var val=(top--)[0];
     var res=top[-1].vec().get_val(val.tonum());
     if (res.type==vm_none) {
@@ -839,7 +845,7 @@ inline void vm::o_slc() {
     top[0].vec().elems.push_back(res);
 }
 
-inline void vm::o_slc2() {
+void vm::o_slc2() {
     var val2=(top--)[0];
     var val1=(top--)[0];
     auto& ref=top[-1].vec().elems;
@@ -868,28 +874,28 @@ inline void vm::o_slc2() {
     }
 }
 
-inline void vm::o_mcallg() {
+void vm::o_mcallg() {
     memr=stack+imm[pc];
     (++top)[0]=memr[0];
     // push value in this memory space on stack
     // to avoid being garbage collected
 }
 
-inline void vm::o_mcalll() {
+void vm::o_mcalll() {
     memr=localr+imm[pc];
     (++top)[0]=memr[0];
     // push value in this memory space on stack
     // to avoid being garbage collected
 }
 
-inline void vm::o_mupval() {
+void vm::o_mupval() {
     memr=&(funcr.func().upval[(imm[pc]>>16)&0xffff].upval()[imm[pc]&0xffff]);
     (++top)[0]=memr[0];
     // push value in this memory space on stack
     // to avoid being garbage collected
 }
 
-inline void vm::o_mcallv() {
+void vm::o_mcallv() {
     var val=top[0];     // index
     var vec=(--top)[0]; // mcall vector, reserved on stack to avoid gc
     if (vec.type==vm_vec) {
@@ -916,7 +922,7 @@ inline void vm::o_mcallv() {
     }
 }
 
-inline void vm::o_mcallh() {
+void vm::o_mcallh() {
     var hash=top[0]; // mcall hash, reserved on stack to avoid gc
     if (hash.type!=vm_hash) {
         die("must call a hash");
@@ -931,7 +937,7 @@ inline void vm::o_mcallh() {
     }
 }
 
-inline void vm::o_ret() {
+void vm::o_ret() {
 /*  +-------------+
 *   | return value| <- top[0]
 *   +-------------+
@@ -974,6 +980,7 @@ inline void vm::o_ret() {
         ngc.ctxreserve();
     }
 }
+
 void vm::run(
     const codegen& gen,
     const linker& linker,
diff --git a/test/life.nas b/test/life.nas
index d5d7c1d..e2cfa0e 100644
--- a/test/life.nas
+++ b/test/life.nas
@@ -28,6 +28,7 @@ var run=func(width,height){
         if(_width>=width) _width=0;
         return map[_height][_width]=='O';
     }
+
     # enable ANSI escape sequence
     if(os.platform()=="windows")
         system("color");
@@ -55,43 +56,48 @@ var run=func(width,height){
 };
 
 var ppm_gen=func(width,height){
+    var pixels=width*height;
+
+    var new_map=func(){
+        var tmp=[];
+        setsize(tmp,pixels);
+        return tmp;
+    }
 
     # iteration counter and trigger for ppm/data generator
     var iter_to_print=0;
 
     var init=func(){
-        var res=new_map(width,height);
+        var res=new_map();
         if(io.exists(".life_data")) {
             var vec=split("\n",io.fin(".life_data"));
             if (num(vec[0])!=width or num(vec[1])!=height) {
                 die("incorrect width or height: "~vec[0]~":"~str(width)~" / "~vec[1]~":"~str(height))
             }
             iter_to_print=num(vec[2]);
-            var data=split("",vec[3]);
-            for(var i=0;i<height;i+=1)
-                for(var j=0;j<width;j+=1)
-                    res[i][j]=num(data[i*width+j]);
+            var data=vec[3];
+            var n="1"[0];
+            for(var i=0;i<pixels;i+=1){
+                res[i]=data[i]==n?1:0;
+            }
             return res;
         }
 
         rand(time(0));
-        for(var i=0;i<height;i+=1)
-            for(var j=0;j<width;j+=1)
-                res[i][j]=0;
+        for(var i=0;i<pixels;i+=1)
+            res[i]=0;
         
         for(var i=int(height/5*2);i<int(height/5*3);i+=1)
             forindex(var j;res[i])
-                res[i][j]=rand()<0.5?1:0;
+                res[i*width+j]=rand()<0.5?1:0;
         return res;
     }
 
     var store=func(){
         var fd=io.open(".life_data","w");
         io.write(fd,str(width)~"\n"~str(height)~"\n"~str(iter_to_print)~"\n");
-        for(var i=0;i<height;i+=1){
-            for(var j=0;j<width;j+=1){
-                io.write(fd,map[i][j]==1?"1":"0");
-            }
+        for(var i=0;i<pixels;i+=1){
+            io.write(fd,map[i]==1?"1":"0");
         }
         io.close(fd);
     }
@@ -103,24 +109,21 @@ var ppm_gen=func(width,height){
         io.write(fd,"P6\n"~width~" "~height~"\n255\n");
         var white=char(255)~char(255)~char(255);
         var black=char(0)~char(0)~char(0);
-        for(var i=0;i<height;i+=1){
-            for(var j=0;j<width;j+=1){
-                var s=map[i][j]==1?white:black;
-                io.write(fd,s);
-            }
+        for(var i=0;i<pixels;i+=1){
+            io.write(fd,map[i]==1?white:black);
         }
         io.close(fd);
     }
 
     var ts=maketimestamp();
-    var bar=process_bar.high_resolution_bar(80);
+    var bar=process_bar.high_resolution_bar(50);
     var map=init();
-    var tmp=new_map(width,height);
+    var tmp=new_map();
     
     var check=func(_width,_height){
         if(_height>=height) _height=0;
         if(_width>=width) _width=0;
-        return map[_height][_width]==1;
+        return map[_height*width+_width]==1;
     }
 
     for(var r=0;r<1001;r+=1){
@@ -128,9 +131,9 @@ var ppm_gen=func(width,height){
         for(var i=0;i<height;i+=1){
             for(var j=0;j<width;j+=1){
                 var cnt=check(j,i+1)+check(j+1,i)+check(j,i-1)+check(j-1,i)+check(j+1,i+1)+check(j-1,i-1)+check(j+1,i-1)+check(j-1,i+1);
-                if(cnt==2)    tmp[i][j]=map[i][j];
-                elsif(cnt==3) tmp[i][j]=1;
-                else          tmp[i][j]=0;
+                if(cnt==2)    tmp[i*width+j]=map[i*width+j];
+                elsif(cnt==3) tmp[i*width+j]=1;
+                else          tmp[i*width+j]=0;
             }
         }
         (map,tmp)=(tmp,map);
diff --git a/test/utf8chk.nas b/test/utf8chk.nas
index 2e47189..37ee852 100644
--- a/test/utf8chk.nas
+++ b/test/utf8chk.nas
@@ -12,19 +12,19 @@ var unicode测试=func(){
 var emoji测试=func(){
     var 💻=print;
     var 🎤="\n";
-    var 🤣="🤣笑嘻了";
-    var 😅="😅差不多得了";
-    var 🤤="🤤收收味";
-    var 🥵="🥵太烧啦";
-    var 🥶="🥶捏麻麻滴冷死了";
-    var 🤢="🤢老八秘制小汉堡🍔";
-    var 🤓="🤓我是傻逼";
-    var 😭="😭你带我走吧😭😭😭";
-    var 👿="👿密麻麻石蜡";
-    var 🤡="🤡居然就是你";
-    var 💩="💩奥利给干了兄弟们";
-    var 🍾="🍾好似，开🍾咯";
-    var 🐘="🐘太🚬🐘了兄弟们";
+    var 🤣="🤣 笑嘻了";
+    var 😅="😅 差不多得了";
+    var 🤤="🤤 收收味";
+    var 🥵="🥵 太烧啦";
+    var 🥶="🥶 我草！冰！";
+    var 🤢="🤢 老八秘制小汉堡 🍔";
+    var 🤓="🤓 我是傻逼";
+    var 😭="😭 你带我走吧 😭😭😭";
+    var 👿="👿 密麻麻石蜡";
+    var 🤡="🤡 居然就是你";
+    var 💩="💩 奥利给干了兄弟们";
+    var 🍾="🍾 好似，开 🍾 咯";
+    var 🐘="🐘 太 🚬🐘 了兄弟们";
     var 📁=[🤣,😅,🤤,🥵,🥶,🤢,🤓,😭,👿,🤡,💩,🍾,🐘];
     var 🗄️={
         🤣:🤣,