diff --git a/README.md b/README.md
index f440acd..fe578cc 100644
--- a/README.md
+++ b/README.md
@@ -39,7 +39,7 @@ headers.__str = fn(a) {
 */
 shy fn handle(req) {
     setmetatable(req.headers, headers)
-    rt 200, string.format('%s %s\n\n%s\n%s', req.method, req.url, req.headers, req.body)
+    rt 200, fmt('%s %s\n\n%s\n%s', req.method, req.url, req.headers, req.body)
 }
 
 // 监听
@@ -71,4 +71,4 @@ if http.listen(':8080', handle) != nil {
   - [x] key为StringExp，而不是NameExp
   - [x] `=` -> `:`, eg: `{a = 'a'}` -> `{a: 'a'}`
 - CLI
-  - [ ] 利用HASH，如果文件内容没变化，就不需要重新编译
\ No newline at end of file
+  - [x] 利用HASH，如果文件内容没变化，就不需要重新编译
\ No newline at end of file
diff --git a/consts/lang.go b/consts/lang.go
index 684608a..376b77f 100644
--- a/consts/lang.go
+++ b/consts/lang.go
@@ -1,6 +1,6 @@
 package consts
 
 var (
-	VERSION   = `0.0.1`
+	VERSION   = `0.1.1`
 	SIGNATURE = `LANG_LK`
 )
\ No newline at end of file
diff --git a/main.go b/main.go
index 8037b53..f7e11fb 100644
--- a/main.go
+++ b/main.go
@@ -1,17 +1,18 @@
 package main
 
 import (
+	"crypto/sha256"
+	"encoding/hex"
 	"flag"
 	"io/ioutil"
 	"os"
-	"strings"
+	"path"
 
 	"git.lolli.tech/lollipopkit/go-lang-lk/compiler"
 	"git.lolli.tech/lollipopkit/go-lang-lk/state"
 )
 
 func main() {
-	compile := flag.Bool("c", false, "compile, not run")
 	flag.Parse()
 
 	file := flag.Arg(0)
@@ -19,7 +20,8 @@ func main() {
 		panic("no input file")
 	}
 
-	compiledFile := strings.Replace(file, ".lk", ".lkc", 1)
+	compiledFileName := getSHA256HashCode([]byte(file)) + ".lkc"
+	compiledFile := path.Join(os.TempDir(), compiledFileName)
 	compiledData, _ := ioutil.ReadFile(compiledFile)
 	
 	if !exist(compiledFile) || sourceChanged(file, compiledFile) {
@@ -39,12 +41,10 @@ func main() {
 		f.Write(compiledData)
 	}
 
-	if !*compile {
-		ls := state.New()
-		ls.OpenLibs()
-		ls.Load(compiledData, file, "bt")
-		ls.Call(0, -1)
-	}
+	ls := state.New()
+	ls.OpenLibs()
+	ls.Load(compiledData, file, "bt")
+	ls.Call(0, -1)
 }
 
 func exist(path string) bool {
@@ -63,3 +63,9 @@ func sourceChanged(source, compiled string) bool {
 	}
 	return s.ModTime().After(c.ModTime())
 }
+
+func getSHA256HashCode(message []byte) string {
+	bytes := sha256.Sum256(message)
+	hashCode := hex.EncodeToString(bytes[:])
+	return hashCode
+}
diff --git a/stdlib/lib_basic.go b/stdlib/lib_basic.go
index b5c194d..13c00ce 100644
--- a/stdlib/lib_basic.go
+++ b/stdlib/lib_basic.go
@@ -7,6 +7,7 @@ import (
 	"strings"
 
 	. "git.lolli.tech/lollipopkit/go-lang-lk/api"
+	"git.lolli.tech/lollipopkit/go-lang-lk/consts"
 )
 
 var baseFuncs = map[string]GoFunction{
@@ -39,6 +40,8 @@ var baseFuncs = map[string]GoFunction{
 	"insert": tabInsert,
 	"delete": tabRemove,
 	"sort":   tabSort,
+	// string
+	"fmt":   strFormat,
 }
 
 // lua-5.3.4/src/lbaselib.c#luaopen_base()
@@ -50,7 +53,7 @@ func OpenBaseLib(ls LkState) int {
 	ls.PushValue(-1)
 	ls.SetField(-2, "_G")
 	/* set global _VERSION */
-	ls.PushString("LK 5.3") // todo
+	ls.PushString(consts.VERSION) // todo
 	ls.SetField(-2, "_VERSION")
 	return 1
 }
@@ -70,6 +73,33 @@ func baseKV(ls LkState) int {
 	return 2
 }
 
+
+// format (formatstring, ···)
+// http://www.lua.org/manual/5.3/manual.html#pdf-string.format
+func strFormat(ls LkState) int {
+	fmtStr := ls.CheckString(1)
+	if len(fmtStr) <= 1 || strings.IndexByte(fmtStr, '%') < 0 {
+		ls.PushString(fmtStr)
+		return 1
+	}
+
+	argIdx := 1
+	arr := parseFmtStr(fmtStr)
+	for i := range arr {
+		if arr[i][0] == '%' {
+			if arr[i] == "%%" {
+				arr[i] = "%"
+			} else {
+				argIdx += 1
+				arr[i] = _fmtArg(arr[i], ls, argIdx)
+			}
+		}
+	}
+
+	ls.PushString(strings.Join(arr, ""))
+	return 1
+}
+
 // print (···)
 // http://www.lua.org/manual/5.3/manual.html#pdf-print
 // lua-5.3.4/src/lbaselib.c#luaB_print()
diff --git a/stdlib/lib_string.go b/stdlib/lib_string.go
index 94a6fab..741fced 100644
--- a/stdlib/lib_string.go
+++ b/stdlib/lib_string.go
@@ -17,7 +17,6 @@ var strLib = map[string]GoFunction{
 	"byte":     strByte,
 	"char":     strChar,
 	"dump":     strDump,
-	"format":   strFormat,
 	"packsize": strPackSize,
 	"pack":     strPack,
 	"unpack":   strUnpack,
@@ -225,34 +224,6 @@ func strUnpack(ls LkState) int {
 	panic("todo: strUnpack!")
 }
 
-/* STRING FORMAT */
-
-// string.format (formatstring, ···)
-// http://www.lua.org/manual/5.3/manual.html#pdf-string.format
-func strFormat(ls LkState) int {
-	fmtStr := ls.CheckString(1)
-	if len(fmtStr) <= 1 || strings.IndexByte(fmtStr, '%') < 0 {
-		ls.PushString(fmtStr)
-		return 1
-	}
-
-	argIdx := 1
-	arr := parseFmtStr(fmtStr)
-	for i := range arr {
-		if arr[i][0] == '%' {
-			if arr[i] == "%%" {
-				arr[i] = "%"
-			} else {
-				argIdx += 1
-				arr[i] = _fmtArg(arr[i], ls, argIdx)
-			}
-		}
-	}
-
-	ls.PushString(strings.Join(arr, ""))
-	return 1
-}
-
 func _fmtArg(tag string, ls LkState, argIdx int) string {
 	switch tag[len(tag)-1] { // specifier
 	case 'c': // character
diff --git a/test/basic.lk b/test/basic.lk
index db5843f..dba81af 100644
--- a/test/basic.lk
+++ b/test/basic.lk
@@ -19,4 +19,4 @@ if #long >= 0 and '' {
 }
 
 print(6 ~/ 2, 6 & 2, 6 / 2)
-print({'a'} .. '', 1 .. 2)
\ No newline at end of file
+print({'a'} .. '', 1 .. 2, _VERSION)
\ No newline at end of file
diff --git a/test/http/listen.lk b/test/http/listen.lk
index 7643307..376f946 100644
--- a/test/http/listen.lk
+++ b/test/http/listen.lk
@@ -13,7 +13,7 @@ headers.__str = fn(a) {
 
 shy fn handle(req) {
     setmetatable(req.headers, headers)
-    rt 200, string.format('%s %s\n\n%s\n%s', req.method, req.url, req.headers, req.body)
+    rt 200, fmt('%s %s\n\n%s\n%s', req.method, req.url, req.headers, req.body)
 }
 
 if http.listen(':8080', handle) != nil {