diff --git a/module/nasocket.cpp b/module/nasocket.cpp
index 71b95c8..7dba4c1 100644
--- a/module/nasocket.cpp
+++ b/module/nasocket.cpp
@@ -8,7 +8,7 @@
 #include <winsock.h>
 #pragma comment(lib,"ws2_32")
 
-class WSAmanager{
+class WSAmanager {
 private:
     WSAData data;
 public:
diff --git a/src/nasal_err.cpp b/src/nasal_err.cpp
index d13471f..5075e71 100644
--- a/src/nasal_err.cpp
+++ b/src/nasal_err.cpp
@@ -1,4 +1,5 @@
 #include "nasal_err.h"
+
 #ifdef _WIN32
 #include <windows.h> // use SetConsoleTextAttribute
 struct for_reset {
@@ -6,7 +7,11 @@ struct for_reset {
     for_reset() {
         GetConsoleScreenBufferInfo(GetStdHandle(STD_OUTPUT_HANDLE), &scr);
     }
-} reset_ter_color;
+    static for_reset* singleton() {
+        static for_reset windows_set;
+        return &windows_set;
+    }
+};
 #endif
 
 std::ostream& back_white(std::ostream& s) {
@@ -57,7 +62,7 @@ std::ostream& white(std::ostream& s) {
 std::ostream& reset(std::ostream& s) {
 #ifdef _WIN32
     SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE),
-        reset_ter_color.scr.wAttributes);
+        for_reset::singleton()->scr.wAttributes);
 #else
     s << "\033[0m";
 #endif
@@ -68,7 +73,22 @@ void flstream::load(const std::string& f) {
     if (file==f) { // don't need to load a loaded file
         return;
     } else {
-        file=f;
+        file = f;
+    }
+
+    if (repl_file_info::instance()->in_repl_mode &&
+        repl_file_info::instance()->repl_file_name==file) {
+        const auto& source = repl_file_info::instance()->repl_file_source;
+        res = {};
+        size_t pos = 0, last = 0;
+        while ((pos = source.find("\n", last))!=std::string::npos) {
+            res.push_back(source.substr(last, pos - last));
+            last = pos + 1;
+        }
+        if (last<source.length()) {
+            res.push_back(source.substr(last));
+        }
+        return;
     }
 
     res.clear();
diff --git a/src/nasal_err.h b/src/nasal_err.h
index 277b059..7044d8c 100644
--- a/src/nasal_err.h
+++ b/src/nasal_err.h
@@ -8,6 +8,18 @@
 
 #include "nasal.h"
 
+struct repl_file_info {
+    bool in_repl_mode = false;
+    std::string repl_file_name = "<nasal-repl>";
+    std::string repl_file_source = "";
+
+    // singleton
+    static repl_file_info* instance() {
+        static repl_file_info info;
+        return &info;
+    }
+};
+
 struct span {
     u32 begin_line;
     u32 begin_column;
diff --git a/src/nasal_lexer.cpp b/src/nasal_lexer.cpp
index f7b6c84..43d3aef 100644
--- a/src/nasal_lexer.cpp
+++ b/src/nasal_lexer.cpp
@@ -62,6 +62,14 @@ void lexer::err_char() {
 }
 
 void lexer::open(const std::string& file) {
+    if (repl_file_info::instance()->in_repl_mode &&
+        repl_file_info::instance()->repl_file_name==file) {
+        err.load(file);
+        filename = file;
+        res = repl_file_info::instance()->repl_file_source;
+        return;
+    }
+
     // check file exsits and it is a regular file
     struct stat buffer;
     if (stat(file.c_str(), &buffer)==0 && !S_ISREG(buffer.st_mode)) {
diff --git a/src/repl.cpp b/src/repl.cpp
index 3be8f19..ef8fea3 100644
--- a/src/repl.cpp
+++ b/src/repl.cpp
@@ -20,16 +20,14 @@ void repl::update_temp_file() {
     for(const auto& i : source) {
         content += i + "\n";
     }
-
-    std::ofstream out(".temp.nas", std::ios::binary);
-    out << content;
+    repl_file_info::instance()->repl_file_source = content;
 }
 
 bool repl::check_need_more_input() {
     while(true) {
         update_temp_file();
         auto nasal_lexer = std::unique_ptr<lexer>(new lexer);
-        if (nasal_lexer->scan(".temp.nas").geterr()) {
+        if (nasal_lexer->scan("<nasal-repl>").geterr()) {
             return false;
         }
 
@@ -67,6 +65,10 @@ void repl::help() {
 bool repl::run() {
     update_temp_file();
 
+    using clk = std::chrono::high_resolution_clock;
+    const auto den = clk::duration::period::den;
+    auto start = clk::now();
+
     auto nasal_lexer = std::unique_ptr<lexer>(new lexer);
     auto nasal_parser = std::unique_ptr<parse>(new parse);
     auto nasal_linker = std::unique_ptr<linker>(new linker);
@@ -74,7 +76,7 @@ bool repl::run() {
     auto nasal_codegen = std::unique_ptr<codegen>(new codegen);
     auto nasal_runtime = std::unique_ptr<vm>(new vm);
 
-    if (nasal_lexer->scan(".temp.nas").geterr()) {
+    if (nasal_lexer->scan("<nasal-repl>").geterr()) {
         return false;
     }
 
@@ -82,7 +84,7 @@ bool repl::run() {
         return false;
     }
 
-    if (nasal_linker->link(*nasal_parser, ".temp.nas", true).geterr()) {
+    if (nasal_linker->link(*nasal_parser, "<nasal-repl>", true).geterr()) {
         return false;
     }
 
@@ -91,6 +93,8 @@ bool repl::run() {
         return false;
     }
 
+    auto end = clk::now();
+    std::clog << "[compile time: " << (end-start).count()*1.0/den << "s]\n";
     nasal_runtime->run(*nasal_codegen, *nasal_linker, {}, false);
 
     return true;
@@ -98,6 +102,9 @@ bool repl::run() {
 
 void repl::execute() {
     source = {};
+    auto repl_file_handle = repl_file_info::instance();
+    repl_file_handle->in_repl_mode = true;
+
     std::cout << "Nasal REPL interpreter(experimental).\n";
     help();
 
@@ -127,9 +134,11 @@ void repl::execute() {
             continue;
         }
 
+        // run program
         if (!run()) {
             source.pop_back();
         }
+
         std::cout << "\n";
     }
 }