diff --git a/module/libkey.nas b/module/libkey.nas
index d692c57..0213b59 100644
--- a/module/libkey.nas
+++ b/module/libkey.nas
@@ -1,10 +1,17 @@
 
-var lib=dylib.dlopen("libkey"~(os.platform()=="windows"?".dll":".so"));
-var kb=lib.nas_kbhit;
-var gt=lib.nas_getch;
-var nb=lib.nas_noblock;
-var call=dylib.limitcall(0);
-
-var kbhit = func(){return call(kb);}
-var getch = func(){return call(gt);}
-var nonblock = func(){return call(nb);}
+var (
+    kbhit,
+    getch,
+    nonblock
+) = func {
+    var lib = dylib.dlopen("libkey"~(os.platform()=="windows"? ".dll":".so"));
+    var kb = lib.nas_kbhit;
+    var gt = lib.nas_getch;
+    var nb = lib.nas_noblock;
+    var call = dylib.limitcall(0);
+    return [
+        func(){return call(kb);},
+        func(){return call(gt);},
+        func(){return call(nb);}
+    ];
+}();
diff --git a/std/lib.nas b/std/lib.nas
index ae1e969..5af1204 100644
--- a/std/lib.nas
+++ b/std/lib.nas
@@ -217,6 +217,35 @@ var println = func(elems...) {
     return __println(elems);
 }
 
+# sort function using quick sort
+# not very efficient... :(
+var sort=func(){
+    srand(); # be aware! this causes global changes
+    var quick_sort_core=func(vec,left,right,cmp){
+        if(left>=right) return nil;
+        var base=left+int(rand()*(right-left));
+        (vec[left],vec[base])=(vec[base],vec[left]);
+        var (i,j,tmp)=(left,right,vec[left]);
+        while(i<j){
+            while(i<j and cmp(tmp,vec[j]))
+                j-=1;
+            vec[i]=vec[j];
+            while(i<j and cmp(vec[i],tmp))
+                i+=1;
+            vec[j]=vec[i];
+            j-=1;
+        }
+        vec[i]=tmp;
+        quick_sort_core(vec,left,i-1,cmp);
+        quick_sort_core(vec,i+1,right,cmp);
+        return nil;
+    }
+    return func(vec,cmp=func(a,b){return a<b;}){
+        quick_sort_core(vec,0,size(vec)-1,cmp);
+        return nil;
+    }
+}();
+
 var isfunc = func(f) {
     return typeof(f)=="func";
 }
diff --git a/std/sort.nas b/std/sort.nas
deleted file mode 100644
index c6ce726..0000000
--- a/std/sort.nas
+++ /dev/null
@@ -1,56 +0,0 @@
-# sort.nas
-# valkmjolnir 2021/4/2
-
-var sort=func(){
-    srand(); # be aware! this causes global changes
-    var quick_sort_core=func(vec,left,right,cmp){
-        if(left>=right) return nil;
-        var base=left+int(rand()*(right-left));
-        (vec[left],vec[base])=(vec[base],vec[left]);
-        var (i,j,tmp)=(left,right,vec[left]);
-        while(i<j){
-            while(i<j and cmp(tmp,vec[j]))
-                j-=1;
-            vec[i]=vec[j];
-            while(i<j and cmp(vec[i],tmp))
-                i+=1;
-            vec[j]=vec[i];
-            j-=1;
-        }
-        vec[i]=tmp;
-        quick_sort_core(vec,left,i-1,cmp);
-        quick_sort_core(vec,i+1,right,cmp);
-        return nil;
-    }
-    return func(vec,cmp=func(a,b){return a<b;}){
-        quick_sort_core(vec,0,size(vec)-1,cmp);
-        return nil;
-    }
-}();
-
-var var_sort=func(){
-    srand(); # be aware! this causes global changes
-    var quick_sort_core=func(vec,left,right){
-        if(left>=right) return nil;
-        var base=left+int(rand()*(right-left));
-        (vec[left],vec[base])=(vec[base],vec[left]);
-        var (i,j,tmp)=(left,right,vec[left]);
-        while(i<j){
-            while(i<j and tmp<vec[j])
-                j-=1;
-            vec[i]=vec[j];
-            while(i<j and vec[i]<tmp)
-                i+=1;
-            vec[j]=vec[i];
-            j-=1;
-        }
-        vec[i]=tmp;
-        quick_sort_core(vec,left,i-1);
-        quick_sort_core(vec,i+1,right);
-        return nil;
-    }
-    return func(vec){
-        quick_sort_core(vec,0,size(vec)-1);
-        return nil;
-    }
-}();
\ No newline at end of file
diff --git a/test/ascii-art.nas b/test/ascii-art.nas
index eec4b6e..893f944 100644
--- a/test/ascii-art.nas
+++ b/test/ascii-art.nas
@@ -1,8 +1,6 @@
 import.std.padding;
 import.std.process_bar;
 
-var (leftpad, rightpad) = (padding.leftpad, padding.rightpad);
-
 var char_ttf=[
     ["    ","    ","    ","    ","    ","    "],
     [" █████╗ ","██╔══██╗","███████║","██╔══██║","██║  ██║","╚═╝  ╚═╝"],
@@ -136,43 +134,43 @@ var curve5=func(line=4){
 var ansi_escape_sequence=func(){
     # decoration
     for(var i=0;i<10;i+=1)
-        print("\e["~i~"m",rightpad(i,4),"\e[0m");
+        print("\e["~i~"m",padding.rightpad(i,4),"\e[0m");
     print("\n");
 
     # 8/16 color
     for(var i=30;i<38;i+=1)
-        print("\e["~i~"m ",rightpad(i,4),"\e[0m");
+        print("\e["~i~"m ",padding.rightpad(i,4),"\e[0m");
     for(var i=30;i<38;i+=1)
-        print("\e["~i~";1m ",rightpad(i,4),"\e[0m");
+        print("\e["~i~";1m ",padding.rightpad(i,4),"\e[0m");
     print("\n");
     for(var i=40;i<48;i+=1)
-        print("\e["~i~"m ",rightpad(i,4),"\e[0m");
+        print("\e["~i~"m ",padding.rightpad(i,4),"\e[0m");
     for(var i=40;i<48;i+=1)
-        print("\e["~i~";1m ",rightpad(i,4),"\e[0m");
+        print("\e["~i~";1m ",padding.rightpad(i,4),"\e[0m");
     print("\n");
     for(var i=90;i<98;i+=1)
-        print("\e["~i~"m ",rightpad(i,4),"\e[0m");
+        print("\e["~i~"m ",padding.rightpad(i,4),"\e[0m");
     for(var i=90;i<98;i+=1)
-        print("\e["~i~";1m ",rightpad(i,4),"\e[0m");
+        print("\e["~i~";1m ",padding.rightpad(i,4),"\e[0m");
     print("\n");
     for(var i=100;i<108;i+=1)
-        print("\e["~i~"m ",rightpad(i,4),"\e[0m");
+        print("\e["~i~"m ",padding.rightpad(i,4),"\e[0m");
     for(var i=100;i<108;i+=1)
-        print("\e["~i~";1m ",rightpad(i,4),"\e[0m");
+        print("\e["~i~";1m ",padding.rightpad(i,4),"\e[0m");
     print("\n");
 
     # 256 color
     for(var i=0;i<16;i+=1) {
         for(var j=0;j<16;j+=1) {
             var code=str(i*16+j);
-            print("\e[38;5;"~code~"m ",rightpad(code,4),"\e[0m");
+            print("\e[38;5;"~code~"m ",padding.rightpad(code,4),"\e[0m");
         }
         print("\n");
     }
     for(var i=0;i<16;i+=1) {
         for(var j=0;j<16;j+=1) {
             var code=str(i*16+j);
-            print("\e[48;5;"~code~"m ",rightpad(code,4),"\e[0m");
+            print("\e[48;5;"~code~"m ",padding.rightpad(code,4),"\e[0m");
         }
         print("\n");
     }
@@ -182,14 +180,14 @@ var ansi_escape_sequence=func(){
     var progress=[0,0,0,0,0,0,0,0];
     var increase=[0.03,0.06,0.04,0.094,0.08,0.09,0.05,0.032];
     foreach(var i;progress) {
-        print("\e[1000D",bar.bar(i)," ",rightpad(str(int(i*100)),3)," % \n");
+        print("\e[1000D",bar.bar(i)," ",padding.rightpad(str(int(i*100)),3)," % \n");
     }
     for(var i=0;i<1/0.03;i+=1) {
         print("\e[1000D","\e["~str(size(progress))~"A");
         forindex(var j;progress) {
             progress[j]+=increase[j];
             progress[j]=progress[j]>1?1:progress[j];
-            print("\e[1000D",bar.bar(progress[j])," ",rightpad(str(int(progress[j]*100)),3)," % \n")
+            print("\e[1000D",bar.bar(progress[j])," ",padding.rightpad(str(int(progress[j]*100)),3)," % \n")
         }
         unix.sleep(0.01);
     }
@@ -203,9 +201,15 @@ if(os.platform()=="windows"){
 
 trans_ttf("just for test");
 trans_ttf(" ValKmjolnir ");
+print("curve 1\n");
 curve1();
+print("curve 2\n");
 curve2();
+print("curve 3\n");
 curve3();
+print("curve 4\n");
 curve4();
+print("curve 5\n");
 curve5();
+print("ANSI escape sequence\n");
 ansi_escape_sequence();
diff --git a/test/calc.nas b/test/calc.nas
index b6a5cb1..f1de5ac 100644
--- a/test/calc.nas
+++ b/test/calc.nas
@@ -1,10 +1,5 @@
 import.std.padding;
 import.std.file;
-import.std.sort;
-
-var sort = sort.sort;
-
-var (leftpad, rightpad) = (padding.leftpad, padding.rightpad);
 
 var source=file.find_all_files_with_extension("./src","cpp","h");
 sort(source,func(a,b){return cmp(a,b)<0});
@@ -55,7 +50,7 @@ var count=func(s,c){
 
 var column=func(number){
     number=number>=1000?substr(str(number/1000),0,3)~'k':str(number);
-    return leftpad(number,6);
+    return padding.leftpad(number,6);
 }
 
 var calc=func(codetype,files,path=""){
@@ -64,20 +59,20 @@ var calc=func(codetype,files,path=""){
     forindex(var i;files){
         var s=io.exists(path~files[i])?io.readfile(path~files[i]):"";
         (line_cnt,semi_cnt)=(count(s,'\n'),count(s,';'));
-        println(rightpad(files[i],padding_length),'|',
+        println(padding.rightpad(files[i],padding_length),'|',
             column(line_cnt),' line |',
             column(semi_cnt),' semi |',
-            leftpad(str(int(size(s)/1024)),4),' kb | ',
+            padding.leftpad(str(int(size(s)/1024)),4),' kb | ',
             md5(s),' |');
         bytes+=size(s);
         ctx~=s;
         line+=line_cnt;
         semi+=semi_cnt;
     }
-    println(rightpad("total:",padding_length),'|',
+    println(padding.rightpad("total:",padding_length),'|',
         column(line),' line |',
         column(semi),' semi |',
-        leftpad(str(int(bytes/1024)),4),' kb | ',
+        padding.leftpad(str(int(bytes/1024)),4),' kb | ',
         md5(ctx),' |\n');
     return int(bytes/1024);
 }
@@ -86,4 +81,4 @@ var all=calc("source code:",source,"src/")
     +calc("lib:",lib,"std/")
     +calc("test file:",testfile,"test/")
     +calc("module:",module,"module/");
-println(rightpad("total:",padding_length),'|',leftpad(str(all),6),' kb   |');
\ No newline at end of file
+println(padding.rightpad("total:",padding_length),'|',padding.leftpad(str(all),6),' kb   |');
\ No newline at end of file
diff --git a/test/console3D.nas b/test/console3D.nas
index d696515..ff8f794 100644
--- a/test/console3D.nas
+++ b/test/console3D.nas
@@ -25,15 +25,26 @@ import.module.libmat;
 
 func(){
     # allocate more spaces
-    var t=[];
-    for(var i=0;i<16384;i+=1)
-        append(t,[],[],[],str(i));
-    t=[];
+    for(var i = 0; i<10; i+=1) {
+        runtime.gc.extend("str");
+        runtime.gc.extend("vec");
+    }
 }();
 
-var (max,min,sqrt,sin,cos,abs)=(math.max,math.min,math.sqrt,math.sin,math.cos,math.abs);
+var (max,min,sqrt,sin,cos,abs)=(
+    math.max,
+    math.min,
+    math.sqrt,
+    math.sin,
+    math.cos,
+    math.abs
+);
+
+var (vec2,vec3)=(
+    libmat.vec2.new,
+    libmat.vec3.new
+);
 
-var (vec2,vec3)=(libmat.vec2.new,libmat.vec3.new);
 var (vec2add,vec2sub,vec2mul,vec2div,vec2len)=(
     libmat.vec2.add,
     libmat.vec2.sub,
@@ -41,6 +52,7 @@ var (vec2add,vec2sub,vec2mul,vec2div,vec2len)=(
     libmat.vec2.div,
     libmat.vec2.len
 );
+
 var (vec3add,vec3sub,vec3mul,vec3div,vec3neg,vec3norm,vec3len,vec3dot)=(
     libmat.vec3.add,
     libmat.vec3.sub,
@@ -51,6 +63,7 @@ var (vec3add,vec3sub,vec3mul,vec3div,vec3neg,vec3norm,vec3len,vec3dot)=(
     libmat.vec3.len,
     libmat.vec3.dot
 );
+
 var (rotateX,rotateY,rotateZ)=(
     libmat.vec3.rx,
     libmat.vec3.ry,
diff --git a/test/coroutine.nas b/test/coroutine.nas
index 0bcb539..4d6c09a 100644
--- a/test/coroutine.nas
+++ b/test/coroutine.nas
@@ -3,8 +3,6 @@
 import.std.process_bar;
 import.std.padding;
 
-var (leftpad, rightpad) = (padding.leftpad, padding.rightpad);
-
 if(os.platform()=="windows"){
     system("chcp 65001");
     system("color");
@@ -108,12 +106,17 @@ for(var t=0;t<10;t+=1){
             coroutine.resume(co);
         if(counter-int(counter/1000)*1000==0){
             var rate=counter/2e5;
-            print(" ",bar.bar(rate)," ",leftpad(str(int(rate*100)),3),"% | ",str(1e3*int(counter/tm.elapsedMSec()))," tasks/s         \r");
+            print(" ",bar.bar(rate)," ",
+                padding.leftpad(str(int(rate*100)),3),"% | ",
+                str(1e3*int(counter/tm.elapsedMSec())),
+                " tasks/s         \r");
         }
     }
 
     tm.stamp();
     for(var i=0;i<1e5;i+=1)
         consumer();
-    println(" ",bar.bar(1)," 100% | ",str(int(1e3*counter/tm.elapsedMSec()))," tasks/s         ");
+    println(" ",bar.bar(1)," 100% | ",
+        str(int(1e3*counter/tm.elapsedMSec())),
+        " tasks/s         ");
 }
\ No newline at end of file
diff --git a/test/datalog.nas b/test/datalog.nas
index 6b0fc5d..4530a24 100644
--- a/test/datalog.nas
+++ b/test/datalog.nas
@@ -1,10 +1,6 @@
-import.std.sort;
 import.std.padding;
 import.std.process_bar;
 
-var sort = sort.sort;
-var (leftpad, rightpad) = (padding.leftpad, padding.rightpad);
-
 var mess=func(vec) {
     srand();
     var s=size(vec);
@@ -30,10 +26,12 @@ var project=func(n) {
         # generate process bar, every 0.2%
         if((i-last_step)/n>1/500) {
             last_step=i;
-            print(" ",bar.bar((i+1)/n)," ",leftpad(str(int((i+1)/n*100)),3),"% | \r");
+            print(" ",bar.bar((i+1)/n)," ",
+                padding.leftpad(str(int((i+1)/n*100)),3),"% | \r");
         }
     }
-    print(" ",bar.bar(1)~" 100% | ",rightpad(str(ts.elapsedMSec()/1000),5)," s | ");
+    print(" ",bar.bar(1)~" 100% | ",
+        padding.rightpad(str(ts.elapsedMSec()/1000),5)," s | ");
 
     mess(color);
 
@@ -44,7 +42,7 @@ var project=func(n) {
         cnt+=1;
     }
 
-    println(rightpad(str(cnt),7)," in ",ts.elapsedMSec()/1000," s");
+    println(padding.rightpad(str(cnt),7)," in ",ts.elapsedMSec()/1000," s");
 }
 
 var select=func(n) {
@@ -66,10 +64,12 @@ var select=func(n) {
         # generate process bar, every 0.2%
         if((i-last_step)/n>1/500) {
             last_step=i;
-            print(" ",bar.bar((i+1)/n)," ",leftpad(str(int((i+1)/n*100)),3),"% | \r");
+            print(" ",bar.bar((i+1)/n)," ",
+                padding.leftpad(str(int((i+1)/n*100)),3),"% | \r");
         }
     }
-    print(" ",bar.bar(1)~" 100% | ",rightpad(str(ts.elapsedMSec()/1000),5)," s | ");
+    print(" ",bar.bar(1)~" 100% | ",
+        padding.rightpad(str(ts.elapsedMSec()/1000),5)," s | ");
 
     mess(color);
     mess(message);
@@ -97,7 +97,7 @@ var select=func(n) {
         }
     }
 
-    println(rightpad(str(cnt),7)," in ",ts.elapsedMSec()/1000," s");
+    println(padding.rightpad(str(cnt),7)," in ",ts.elapsedMSec()/1000," s");
 }
 
 var cartesian=func(n) {
@@ -119,10 +119,12 @@ var cartesian=func(n) {
         # generate process bar, every 0.2%
         if((i-last_step)/n>1/500) {
             last_step=i;
-            print(" ",bar.bar((i+1)/n)," ",leftpad(str(int((i+1)/n*100)),3),"% | \r");
+            print(" ",bar.bar((i+1)/n)," ",
+                padding.leftpad(str(int((i+1)/n*100)),3),"% | \r");
         }
     }
-    print(" ",bar.bar(1)~" 100% | ",rightpad(str(ts.elapsedMSec()/1000),5)," s | ");
+    print(" ",bar.bar(1)~" 100% | ",
+        padding.rightpad(str(ts.elapsedMSec()/1000),5)," s | ");
 
     mess(color);
     mess(message);
@@ -143,7 +145,7 @@ var cartesian=func(n) {
         }
     }
 
-    println(rightpad(str(size(res)),7)," in ",ts.elapsedMSec()/1000," s");
+    println(padding.rightpad(str(size(res)),7)," in ",ts.elapsedMSec()/1000," s");
 }
 
 println("project");
diff --git a/test/md5compare.nas b/test/md5compare.nas
index 060cbae..42c5133 100644
--- a/test/md5compare.nas
+++ b/test/md5compare.nas
@@ -1,9 +1,8 @@
 import.test.md5_self;
 import.std.process_bar;
 import.std.file;
-srand();
 
-var _md5 = md5_self._md5;
+srand();
 
 var compare=func() {
     var ch=[
@@ -24,7 +23,7 @@ var compare=func() {
             }
             byte+=size(s);
             var res=md5(s);
-            if(cmp(res,_md5(s))) {
+            if(cmp(res,md5_self._md5(s))) {
                 die("error: "~str(i));
             }
             if (i-begin-int((i-begin)/4)*4==0) {
@@ -75,7 +74,7 @@ var filechecksum=func(){
         var f=io.readfile(files[i]);
         var res=md5(f);
         byte+=size(f);
-        if(cmp(res,_md5(f))){
+        if(cmp(res,md5_self._md5(f))){
             die("error: "~files[i]);
         }
         print(
diff --git a/test/quick_sort.nas b/test/quick_sort.nas
index 53ce809..af10a5f 100644
--- a/test/quick_sort.nas
+++ b/test/quick_sort.nas
@@ -1,10 +1,32 @@
-import.std.sort;
 
-var var_sort = sort.var_sort;
-var sort = sort.sort;
+var var_sort=func(){
+    srand(); # be aware! this causes global changes
+    var quick_sort_core=func(vec,left,right){
+        if(left>=right) return nil;
+        var base=left+int(rand()*(right-left));
+        (vec[left],vec[base])=(vec[base],vec[left]);
+        var (i,j,tmp)=(left,right,vec[left]);
+        while(i<j){
+            while(i<j and tmp<vec[j])
+                j-=1;
+            vec[i]=vec[j];
+            while(i<j and vec[i]<tmp)
+                i+=1;
+            vec[j]=vec[i];
+            j-=1;
+        }
+        vec[i]=tmp;
+        quick_sort_core(vec,left,i-1);
+        quick_sort_core(vec,i+1,right);
+        return nil;
+    }
+    return func(vec){
+        quick_sort_core(vec,0,size(vec)-1);
+        return nil;
+    }
+}();
 
-
-var vec=[];
+var vec = [];
 setsize(vec, 1e4);
 rand(time(0));
 for(var i=0;i<1e4;i+=1)
diff --git a/test/snake.nas b/test/snake.nas
index fe25e83..cad86a6 100644
--- a/test/snake.nas
+++ b/test/snake.nas
@@ -1,4 +1,5 @@
 import.module.libkey;
+
 var list=func(){
     var (begin,end,len)=(nil,nil,0);
     return{
diff --git a/test/word_collector.nas b/test/word_collector.nas
index 1a917fb..9e801cc 100644
--- a/test/word_collector.nas
+++ b/test/word_collector.nas
@@ -1,5 +1,3 @@
-import.std.sort;
-var sort = sort.sort;
 
 var to_lower=func(s){
     var tmp="";
diff --git a/tools/search_file.nas b/tools/search_file.nas
index 5716578..5329025 100644
--- a/tools/search_file.nas
+++ b/tools/search_file.nas
@@ -1,5 +1,4 @@
 import.std.file;
-import.std.sort;
 
 if (size(arg)!=1) {
     println("need a key string to search files.");
@@ -21,7 +20,7 @@ var do_flat = func(vec) {
             append(flat, d.dir~"/"~f);
         }
     }
-    sort.sort(flat, func(a,b){return cmp(a,b)<0});
+    sort(flat, func(a,b){return cmp(a,b)<0});
     return flat;
 }