diff --git a/module/libfib.nas b/module/libfib.nas
index 078630f..d5e92f6 100644
--- a/module/libfib.nas
+++ b/module/libfib.nas
@@ -1,4 +1,5 @@
 use std.dylib;
+use std.os;
 
 var _dl = dylib.dlopen("libfib."~(os.platform()=="windows"?"dll":"so"));
 
diff --git a/module/libjson.nas b/module/libjson.nas
index eefa7fa..e9209a3 100644
--- a/module/libjson.nas
+++ b/module/libjson.nas
@@ -2,6 +2,7 @@
 # 2023/11/27 ValKmjolnir
 
 use std.dylib;
+use std.os;
 
 var _dynamic_lib = dylib.dlopen("libjson."~(os.platform()=="windows"?"dll":"so"));
 var _stringify = _dynamic_lib.stringify;
diff --git a/module/libkey.nas b/module/libkey.nas
index 564266b..26f46da 100644
--- a/module/libkey.nas
+++ b/module/libkey.nas
@@ -1,4 +1,5 @@
 use std.dylib;
+use std.os;
 
 var (
     kbhit,
diff --git a/module/libmat.nas b/module/libmat.nas
index be7ef60..cbf02c9 100644
--- a/module/libmat.nas
+++ b/module/libmat.nas
@@ -1,4 +1,5 @@
 use std.dylib;
+use std.os;
 
 var _dl = dylib.dlopen("libmat."~(os.platform()=="windows"?"dll":"so"));
 
diff --git a/module/libsock.nas b/module/libsock.nas
index d8ace4e..e686cf1 100644
--- a/module/libsock.nas
+++ b/module/libsock.nas
@@ -1,4 +1,5 @@
 use std.dylib;
+use std.os;
 
 var socket = func() {
     var lib = dylib.dlopen("libnasock"~(os.platform()=="windows"? ".dll":".so"));
diff --git a/src/nasal_gc.cpp b/src/nasal_gc.cpp
index ed95a99..e402447 100644
--- a/src/nasal_gc.cpp
+++ b/src/nasal_gc.cpp
@@ -197,7 +197,7 @@ void gc::extend(const vm_type type) {
         memory.push_back(tmp);
         unused[index].push_back(tmp);
     }
-
+    // if incr[index] = 1, this will always be 1
     incr[index] = incr[index]+incr[index]/2;
 }
 
diff --git a/src/nasal_gc.h b/src/nasal_gc.h
index e1c9a39..47d174c 100644
--- a/src/nasal_gc.h
+++ b/src/nasal_gc.h
@@ -45,11 +45,11 @@ struct gc {
         128, // vm_str
         128, // vm_vec
         64,  // vm_hash
-        128, // vm_func
+        256, // vm_func
         256, // vm_upval
         16,  // vm_obj
         16,  // vm_co
-        2,   // vm_map
+        1,   // vm_map
     };
 
     /* values for analysis */
diff --git a/std/csv.nas b/std/csv.nas
index 7423360..c2d843d 100644
--- a/std/csv.nas
+++ b/std/csv.nas
@@ -1,5 +1,7 @@
 # lib csv.nas
 # ValKmjolnir 2022/10/15
+use std.io;
+
 var read = func(path, delimeter=",", endline="\n") {
     var context = io.readfile(path);
     context = split(endline, context);
@@ -13,4 +15,4 @@ var read = func(path, delimeter=",", endline="\n") {
         property: context[0],
         data: context[1:]
     };
-}
\ No newline at end of file
+}
diff --git a/std/dylib.nas b/std/dylib.nas
index 92f5bcf..a808653 100644
--- a/std/dylib.nas
+++ b/std/dylib.nas
@@ -2,6 +2,9 @@
 # 2023 by ValKmjolnir
 # dylib is the core hashmap for developers to load their own library.
 # for safe using dynamic library, you could use 'module' in stl/module.nas
+use std.os;
+use std.io;
+use std.unix;
 
 # open dynamic lib. return a hash including dl pointer and function pointers
 var dlopen = func(libname) {
diff --git a/std/fg_env.nas b/std/fg_env.nas
index ffe40f7..46c3878 100644
--- a/std/fg_env.nas
+++ b/std/fg_env.nas
@@ -2,6 +2,7 @@
 # ValKmjolnir 2022
 use std.runtime;
 use std.coroutine;
+use std.os;
 
 println("-------------------------------------------------------------");
 println(" FlightGear simulated-env for developers project, since 2019");
diff --git a/std/file.nas b/std/file.nas
index cc033fa..1138a54 100644
--- a/std/file.nas
+++ b/std/file.nas
@@ -1,5 +1,7 @@
 # lib file.nas
 # ValKmjolnir 2022/3/6
+use std.io;
+use std.unix;
 
 var SEEK_SET = io.SEEK_SET;
 
diff --git a/std/io.nas b/std/io.nas
index d2a950a..bbc9e74 100644
--- a/std/io.nas
+++ b/std/io.nas
@@ -72,3 +72,21 @@ var stdin = func() { return __stdin; }();
 var stdout = func() { return __stdout;}();
 
 var stderr = func() { return __stderr; }();
+
+# get file status. using data from stat
+var fstat = func(filename) {
+    var s = stat(filename);
+    return {
+        st_dev: s[0],
+        st_ino: s[1],
+        st_mode: s[2],
+        st_nlink: s[3],
+        st_uid: s[4],
+        st_gid: s[5],
+        st_rdev: s[6],
+        st_size: s[7],
+        st_atime: s[8],
+        st_mtime: s[9],
+        st_ctime: s[10]
+    };
+}
diff --git a/std/lib.nas b/std/lib.nas
index bb2a408..60d7eca 100644
--- a/std/lib.nas
+++ b/std/lib.nas
@@ -1,9 +1,6 @@
 # lib.nas
 # 2019 ValKmjolnir
 use std.math;
-use std.io;
-use std.os;
-use std.unix;
 
 # print is used to print all things in nasal, try and see how it works.
 # this function uses std::cout to output logs.
@@ -349,24 +346,6 @@ var md5 = func(str) {
     return __md5(str);
 }
 
-# get file status. using data from io.stat
-var fstat = func(filename) {
-    var s = io.stat(filename);
-    return {
-        st_dev: s[0],
-        st_ino: s[1],
-        st_mode: s[2],
-        st_nlink: s[3],
-        st_uid: s[4],
-        st_gid: s[5],
-        st_rdev: s[6],
-        st_size: s[7],
-        st_atime: s[8],
-        st_mtime: s[9],
-        st_ctime: s[10]
-    };
-}
-
 # important global constants
 var D2R = math.pi / 180;         # degree to radian
 var R2D = 180 / math.pi;         # radian to degree
diff --git a/std/log.nas b/std/log.nas
index ce22517..432256c 100644
--- a/std/log.nas
+++ b/std/log.nas
@@ -1,5 +1,7 @@
 # log.nas
 # ValKmjolnir 2022/6/14
+use std.os;
+
 var log = func() {
     var (log_date,log_time,prefix)=(1,1,"");
     var os_time="";
diff --git a/std/phi.nas b/std/phi.nas
index a185c6a..2602d39 100644
--- a/std/phi.nas
+++ b/std/phi.nas
@@ -5,6 +5,8 @@
 
 use module.libsock;
 use std.json;
+use std.os;
+use std.unix;
 
 var _raw_str = func(s) {
     var v = split("", s);
diff --git a/std/process_bar.nas b/std/process_bar.nas
index cac9f07..6bf76aa 100644
--- a/std/process_bar.nas
+++ b/std/process_bar.nas
@@ -1,6 +1,8 @@
 # process_bar.nas
 # ValKmjolnir 2022/6/14
 # this file is inspired by a Python lib: alive_progress
+use std.os;
+use std.unix;
 
 var bar = func() {
     var bar = {
@@ -240,96 +242,96 @@ var default_bar = func(name = "classic", length = 20) {
     if (typeof(name)!="str")
         name="classic";
     if (name=="classic")
-        return process_bar.bar("sharp","point","bracket",length);
+        return bar("sharp","point","bracket",length);
     elsif (name=="classic2")
-        return process_bar.bar("equal","point","bracket",length);
+        return bar("equal","point","bracket",length);
     elsif (name=="classic3")
-        return process_bar.bar("sharp","point","line",length);
+        return bar("sharp","point","line",length);
     elsif (name=="classic4")
-        return process_bar.bar("equal","point","line",length);
+        return bar("equal","point","line",length);
     elsif (name=="triangle")
-        return process_bar.bar("solid_triangle_right","hollow_triangle_right","angle_bracket",length);
+        return bar("solid_triangle_right","hollow_triangle_right","angle_bracket",length);
     elsif (name=="dots")
-        return process_bar.bar("solid_circle","hollow_circle","curve",length);
+        return bar("solid_circle","hollow_circle","curve",length);
     elsif (name=="ticks")
-        return process_bar.bar("tick","space","line",length);
+        return bar("tick","space","line",length);
     elsif (name=="deep_shadow")
-        return process_bar.bar("deep_shadow","light_shadow","line",length);
+        return bar("deep_shadow","light_shadow","line",length);
     elsif (name=="block")
-        return process_bar.bar("block","light_shadow","line",length);
+        return bar("block","light_shadow","line",length);
     elsif (name=="oneline")
-        return process_bar.bar("line","space","space",length);
+        return bar("line","space","space",length);
     else
-        return process_bar.bar("sharp","point","bracket",length);
+        return bar("sharp","point","bracket",length);
 }
 
 var default_spinner = func(name = "classic", repeat = 1) {
     if (typeof(name)!="str")
         name="classic";
     if (name=="rise")
-        return process_bar.spinner("rise",repeat);
+        return spinner("rise",repeat);
     elsif (name=="vertical")
-        return process_bar.spinner("vertical",repeat);
+        return spinner("vertical",repeat);
     elsif (name=="dot")
-        return process_bar.spinner("dot",repeat);
+        return spinner("dot",repeat);
     elsif (name=="dots")
-        return process_bar.spinner("dots",repeat);
+        return spinner("dots",repeat);
     elsif (name=="arrow")
-        return process_bar.spinner("arrow",repeat);
+        return spinner("arrow",repeat);
     elsif (name=="classic")
-        return process_bar.spinner("classic",repeat);
+        return spinner("classic",repeat);
     elsif (name=="balls")
-        return process_bar.spinner("balls",repeat);
+        return spinner("balls",repeat);
     elsif (name=="dots_wave")
-        return process_bar.spinner("dots_wave",repeat);
+        return spinner("dots_wave",repeat);
     elsif (name=="pulse")
-        return process_bar.spinner("pulse",repeat);
+        return spinner("pulse",repeat);
     elsif (name=="wave")
-        return process_bar.spinner("wave",repeat);
+        return spinner("wave",repeat);
     elsif (name=="short_wave")
-        return process_bar.spinner("short_wave",repeat);
+        return spinner("short_wave",repeat);
     elsif (name=="fish")
-        return process_bar.spinner("fish",repeat);
+        return spinner("fish",repeat);
     elsif (name=="happy")
-        return process_bar.spinner("happy",repeat);
+        return spinner("happy",repeat);
     elsif (name=="wait")
-        return process_bar.spinner("wait",repeat);
+        return spinner("wait",repeat);
     elsif (name=="stars")
-        return process_bar.spinner("stars",repeat);
+        return spinner("stars",repeat);
     else
-        return process_bar.spinner("classic",repeat);
+        return spinner("classic",repeat);
 }
 
 var show = func() {
     print("\ec");
     var bars={
-        "classic    ":process_bar.default_bar("classic",40),
-        "classic2   ":process_bar.default_bar("classic2",40),
-        "classic3   ":process_bar.default_bar("classic3",40),
-        "classic4   ":process_bar.default_bar("classic4",40),
-        "triangle   ":process_bar.default_bar("triangle",40),
-        "dots       ":process_bar.default_bar("dots",40),
-        "ticks      ":process_bar.default_bar("ticks",40),
-        "deep_shadow":process_bar.default_bar("deep_shadow",40),
-        "block      ":process_bar.default_bar("block",40),
-        "oneline    ":process_bar.default_bar("oneline",40)
+        "classic    ":default_bar("classic",40),
+        "classic2   ":default_bar("classic2",40),
+        "classic3   ":default_bar("classic3",40),
+        "classic4   ":default_bar("classic4",40),
+        "triangle   ":default_bar("triangle",40),
+        "dots       ":default_bar("dots",40),
+        "ticks      ":default_bar("ticks",40),
+        "deep_shadow":default_bar("deep_shadow",40),
+        "block      ":default_bar("block",40),
+        "oneline    ":default_bar("oneline",40)
     };
     var spinners={
-        "rise       ":process_bar.default_spinner("rise",16),
-        "vertical   ":process_bar.default_spinner("vertical",16),
-        "dot        ":process_bar.default_spinner("dot",16),
-        "dots       ":process_bar.default_spinner("dots",16),
-        "arrow      ":process_bar.default_spinner("arrow",16),
-        "classic    ":process_bar.default_spinner("classic",16),
-        "balls      ":process_bar.default_spinner("balls",4),
-        "dots_wave  ":process_bar.default_spinner("dots_wave",2),
-        "pulse      ":process_bar.default_spinner("pulse",1),
-        "wave       ":process_bar.default_spinner("wave",2),
-        "short_wave ":process_bar.default_spinner("short_wave",4),
-        "fish       ":process_bar.default_spinner("fish",1),
-        "happy      ":process_bar.default_spinner("happy",1),
-        "wait       ":process_bar.default_spinner("wait",1),
-        "stars      ":process_bar.default_spinner("stars",1)
+        "rise       ":default_spinner("rise",16),
+        "vertical   ":default_spinner("vertical",16),
+        "dot        ":default_spinner("dot",16),
+        "dots       ":default_spinner("dots",16),
+        "arrow      ":default_spinner("arrow",16),
+        "classic    ":default_spinner("classic",16),
+        "balls      ":default_spinner("balls",4),
+        "dots_wave  ":default_spinner("dots_wave",2),
+        "pulse      ":default_spinner("pulse",1),
+        "wave       ":default_spinner("wave",2),
+        "short_wave ":default_spinner("short_wave",4),
+        "fish       ":default_spinner("fish",1),
+        "happy      ":default_spinner("happy",1),
+        "wait       ":default_spinner("wait",1),
+        "stars      ":default_spinner("stars",1)
     };
     var bar_key=keys(bars);
     var spin_key=keys(spinners);
diff --git a/std/udp.nas b/std/udp.nas
index 6f6210b..0f4efbf 100644
--- a/std/udp.nas
+++ b/std/udp.nas
@@ -1,4 +1,6 @@
 use module.libsock;
+use std.os;
+use std.unix;
 
 var udp_server = func(hostname, port, retry_delay = 5) {
     var socket = libsock.socket;
diff --git a/std/unix.nas b/std/unix.nas
index 88f0282..a966c09 100644
--- a/std/unix.nas
+++ b/std/unix.nas
@@ -1,6 +1,8 @@
 # unix.nas
 # 2023 by ValKmjolnir
 use std.bits;
+use std.os;
+use std.io;
 
 var _S_IFDIR = 0x4000;
 var _S_IFREG = 0x8000;
@@ -70,5 +72,5 @@ var getenv = func(envvar) {
 }
 
 var getpath = func() {
-    return split(os.platform()=="windows"? ";":":", unix.getenv("PATH"));
+    return split(os.platform()=="windows"? ";":":", getenv("PATH"));
 }
diff --git a/test/ascii-art.nas b/test/ascii-art.nas
index 95c53ea..1ea8bdf 100644
--- a/test/ascii-art.nas
+++ b/test/ascii-art.nas
@@ -1,5 +1,7 @@
 use std.padding;
 use std.process_bar;
+use std.os;
+use std.unix;
 
 var char_ttf=[
     ["    ","    ","    ","    ","    ","    "],
diff --git a/test/bf.nas b/test/bf.nas
index 546446c..7c4c4bf 100644
--- a/test/bf.nas
+++ b/test/bf.nas
@@ -1,3 +1,5 @@
+use std.os;
+
 var mandelbrot=
 "[A mandelbrot set fractal viewer in brainf*** written by Erik Bosman]
 +++++++++++++[->++>>>+++++>++>+<<<<<<]>>>>>++++++>--->>>>>>>>>>+++++++++++++++[[
diff --git a/test/bfconvertor.nas b/test/bfconvertor.nas
index 074c844..388a4f3 100644
--- a/test/bfconvertor.nas
+++ b/test/bfconvertor.nas
@@ -1,3 +1,5 @@
+use std.io;
+
 var mandelbrot=
 "[A mandelbrot set fractal viewer in brainf*** written by Erik Bosman]
 +++++++++++++[->++>>>+++++>++>+<<<<<<]>>>>>++++++>--->>>>>>>>>>+++++++++++++++[[
diff --git a/test/bfs.nas b/test/bfs.nas
index 3775981..294f292 100644
--- a/test/bfs.nas
+++ b/test/bfs.nas
@@ -1,4 +1,6 @@
 use std.queue;
+use std.os;
+use std.unix;
 
 rand(time(0));
 var pixel=[' ','#','.','*'];
diff --git a/test/burningship.nas b/test/burningship.nas
index 076feff..c3a5b68 100644
--- a/test/burningship.nas
+++ b/test/burningship.nas
@@ -1,4 +1,6 @@
 use std.process_bar;
+use std.os;
+use std.io;
 
 var ppm = func(filename, width, height, RGB) {
     # P3 use ASCII number
diff --git a/test/calc.nas b/test/calc.nas
index 3088387..caadb7f 100644
--- a/test/calc.nas
+++ b/test/calc.nas
@@ -1,5 +1,6 @@
 use std.padding;
 use std.file;
+use std.io;
 
 var source = file.find_all_files_with_extension("./src", "cpp", "h");
 sort(source, func(a, b) {return cmp(a, b)<0});
diff --git a/test/coroutine.nas b/test/coroutine.nas
index b101049..deb1c1d 100644
--- a/test/coroutine.nas
+++ b/test/coroutine.nas
@@ -3,6 +3,7 @@
 use std.coroutine;
 use std.process_bar;
 use std.padding;
+use std.os;
 
 if (os.platform()=="windows") {
     system("chcp 65001");
diff --git a/test/diff.nas b/test/diff.nas
index 9a7a492..40b2a86 100644
--- a/test/diff.nas
+++ b/test/diff.nas
@@ -1,3 +1,5 @@
+use std.io;
+
 var myers = func(src,dst,show_table=0) {
     (src,dst)=(split("\n",src),split("\n",dst));
     append(src,"");
diff --git a/test/feigenbaum.nas b/test/feigenbaum.nas
index 66b4d2a..760bd50 100644
--- a/test/feigenbaum.nas
+++ b/test/feigenbaum.nas
@@ -1,4 +1,6 @@
 use std.process_bar;
+use std.os;
+use std.io;
 
 var ppm = func(filename, width, height, RGB) {
     # P3 use ASCII number
diff --git a/test/filesystem.nas b/test/filesystem.nas
index 92d6521..27d67e9 100644
--- a/test/filesystem.nas
+++ b/test/filesystem.nas
@@ -1,3 +1,7 @@
+use std.os;
+use std.io;
+use std.unix;
+
 var files = func(path) {
     if (!io.exists(path))
         return [];
diff --git a/test/flush_screen.nas b/test/flush_screen.nas
index 499797a..e9937f4 100644
--- a/test/flush_screen.nas
+++ b/test/flush_screen.nas
@@ -1,4 +1,5 @@
 use module.libkey;
+use std.unix;
 
 srand();
 
diff --git a/test/gc_test.nas b/test/gc_test.nas
index fd3f28e..8263c77 100644
--- a/test/gc_test.nas
+++ b/test/gc_test.nas
@@ -1,4 +1,5 @@
 use std.runtime;
+use std.os;
 
 var test_func = func(test_processes...) {
     var test_process_total = maketimestamp();
diff --git a/test/hexdump.nas b/test/hexdump.nas
index b90606d..cf5c66b 100644
--- a/test/hexdump.nas
+++ b/test/hexdump.nas
@@ -2,6 +2,8 @@
 # 2021/8/13
 use std.file;
 use std.runtime;
+use std.os;
+use std.io;
 
 # init
 var hex = func() {
diff --git a/test/httptest.nas b/test/httptest.nas
index 3ec6719..ee919fb 100644
--- a/test/httptest.nas
+++ b/test/httptest.nas
@@ -1,4 +1,7 @@
 use module.libsock;
+use std.os;
+use std.io;
+use std.unix;
 
 var socket = libsock.socket;
 
diff --git a/test/jsonrpc.nas b/test/jsonrpc.nas
index c5dfaa7..3b7f95b 100644
--- a/test/jsonrpc.nas
+++ b/test/jsonrpc.nas
@@ -1,6 +1,8 @@
 use module.libsock;
 use std.json;
 use std.runtime;
+use std.os;
+use std.unix;
 
 var socket = libsock.socket;
 
diff --git a/test/juliaset.nas b/test/juliaset.nas
index e6d387a..0bb5e63 100644
--- a/test/juliaset.nas
+++ b/test/juliaset.nas
@@ -1,4 +1,6 @@
 use std.process_bar;
+use std.os;
+use std.io;
 
 var ppm = func(filename, width, height, RGB) {
     # P3 use ASCII number
diff --git a/test/lexer.nas b/test/lexer.nas
index 6055a90..211ed04 100644
--- a/test/lexer.nas
+++ b/test/lexer.nas
@@ -1,3 +1,5 @@
+use std.io;
+
 var lexer = func(file) {
     var (ptr,token)=(0,[]);
     var s=io.readfile(file);
diff --git a/test/life.nas b/test/life.nas
index 8bdcbcb..18e0b25 100644
--- a/test/life.nas
+++ b/test/life.nas
@@ -1,5 +1,8 @@
 use std.process_bar;
 use std.runtime;
+use std.os;
+use std.io;
+use std.unix;
 
 var new_map = func(width,height) {
     var tmp=[];
diff --git a/test/mandelbrotset.nas b/test/mandelbrotset.nas
index 072a37d..c4573bc 100644
--- a/test/mandelbrotset.nas
+++ b/test/mandelbrotset.nas
@@ -1,4 +1,6 @@
 use std.process_bar;
+use std.os;
+use std.io;
 
 var ppm = func(filename, width, height, RGB) {
     # P3 use ASCII number
diff --git a/test/mcpu.nas b/test/mcpu.nas
index 7860d2c..d1ade9b 100644
--- a/test/mcpu.nas
+++ b/test/mcpu.nas
@@ -1,4 +1,5 @@
 use std.bits;
+use std.os;
 
 var inst={
     inst_stop:0,
diff --git a/test/md5compare.nas b/test/md5compare.nas
index 5bf7f47..1fcfda7 100644
--- a/test/md5compare.nas
+++ b/test/md5compare.nas
@@ -1,6 +1,8 @@
 use test.md5_self;
 use std.process_bar;
 use std.file;
+use std.os;
+use std.io;
 
 srand();
 
diff --git a/test/module_test.nas b/test/module_test.nas
index de7228f..5eec70c 100644
--- a/test/module_test.nas
+++ b/test/module_test.nas
@@ -1,3 +1,4 @@
+use std.os;
 use std.dylib;
 use module.libfib;
 
diff --git a/test/occupation.nas b/test/occupation.nas
index 6cd2f93..577539e 100644
--- a/test/occupation.nas
+++ b/test/occupation.nas
@@ -2,6 +2,9 @@ use std.coroutine;
 use std.process_bar;
 use module.libkey;
 use std.runtime;
+use std.os;
+use std.io;
+use std.unix;
 
 var is_windows_platform=os.platform()=="windows";
 var is_macos_platform=os.platform()=="macOS";
diff --git a/test/qrcode.nas b/test/qrcode.nas
index 3b4c4c1..04fb12a 100644
--- a/test/qrcode.nas
+++ b/test/qrcode.nas
@@ -1,3 +1,4 @@
+use std.os;
 var code=[
     [1,1,1,1,1,1,1,0,1,0,0,1,1,0,1,0,1,0,1,1,0,0,1,1,1,1,1,1,1],
     [1,0,0,0,0,0,1,0,0,1,1,0,0,1,0,0,0,1,1,1,1,0,1,0,0,0,0,0,1],
diff --git a/test/snake.nas b/test/snake.nas
index dec06ff..3a314b8 100644
--- a/test/snake.nas
+++ b/test/snake.nas
@@ -2,6 +2,8 @@ use module.libkey;
 use std.list;
 use std.runtime;
 use std.coroutine;
+use std.os;
+use std.unix;
 
 var game = func(x,y) {
     rand(time(0));
diff --git a/test/tetris.nas b/test/tetris.nas
index 50ebe74..3493c2c 100644
--- a/test/tetris.nas
+++ b/test/tetris.nas
@@ -1,5 +1,7 @@
 use module.libkey;
 use std.runtime;
+use std.os;
+use std.unix;
 
 var color=[
     "\e[31m","\e[32m","\e[33m","\e[34m","\e[35m","\e[36m",
diff --git a/test/udptest.nas b/test/udptest.nas
index 2275f93..94c80f5 100644
--- a/test/udptest.nas
+++ b/test/udptest.nas
@@ -1,4 +1,5 @@
 use std.udp;
+use std.unix;
 
 var argument = arg[0];
 if (argument=="server") {
diff --git a/test/watchdog.nas b/test/watchdog.nas
index 1cb53a0..2e315fd 100644
--- a/test/watchdog.nas
+++ b/test/watchdog.nas
@@ -1,4 +1,7 @@
 use std.runtime;
+use std.os;
+use std.io;
+use std.unix;
 
 var os_time = func() {
     return "[\e[33;1m"~os.time()~"\e[0m] ";
@@ -35,7 +38,7 @@ if (size(argv)==2) {
     args=split(" ",argv[1]);
 }
 
-var modified_time=fstat(filename).st_mtime;
+var modified_time = io.fstat(filename).st_mtime;
 println(os_time(),info_hd(),"\e[1mwatching ",filename," ..\e[0m");
 while(1) {
     unix.sleep(1);
@@ -43,7 +46,7 @@ while(1) {
         println(os_time(),err_hd(),"\e[1mfile <",filename,"> does not exist\e[0m");
         break;
     }
-    var latest_modified_time=fstat(filename).st_mtime;
+    var latest_modified_time = io.fstat(filename).st_mtime;
     if (latest_modified_time!=modified_time) {
         modified_time=latest_modified_time;
         println(os_time(),modified_hd(),"\e[1m",filename,"\e[0m");
diff --git a/test/wavecollapse.nas b/test/wavecollapse.nas
index 1cdbf90..5c34caa 100644
--- a/test/wavecollapse.nas
+++ b/test/wavecollapse.nas
@@ -1,5 +1,7 @@
 # wave collapse function 2022/4/10
 # by ValKmjolnir
+use std.os;
+
 srand();
 var table=[
     # c ,w,a,s,d
diff --git a/test/word_collector.nas b/test/word_collector.nas
index 38e33db..4b2eeca 100644
--- a/test/word_collector.nas
+++ b/test/word_collector.nas
@@ -1,4 +1,5 @@
 use std.runtime;
+use std.io;
 
 var to_lower = func(s) {
     var tmp="";
diff --git a/tools/file2ppm.nas b/tools/file2ppm.nas
index b2498dc..0459c0a 100644
--- a/tools/file2ppm.nas
+++ b/tools/file2ppm.nas
@@ -1,3 +1,4 @@
+use std.io;
 
 var ppm = func(filename, buffer) {
     # P3 use ASCII number
diff --git a/tools/push.nas b/tools/push.nas
index c4c1a60..61aefea 100644
--- a/tools/push.nas
+++ b/tools/push.nas
@@ -1,3 +1,5 @@
+use std.os;
+use std.unix;
 
 println("[", os.time(), "] (=.=) auto push, please wait...");
 
diff --git a/tools/search_file.nas b/tools/search_file.nas
index 307f0b0..242f326 100644
--- a/tools/search_file.nas
+++ b/tools/search_file.nas
@@ -1,6 +1,7 @@
 use std.file;
 use std.padding;
 use std.process_bar;
+use std.io;
 
 var tips = func() {
     println("usage:");
@@ -29,7 +30,7 @@ foreach(var f; all_files) {
     }
     var begin = substr(f, 0, pos);
     var end = pos+size(needle)>=size(f)? "":substr(f, pos+size(needle), size(f));
-    var file_size = fstat(f).st_size;
+    var file_size = io.fstat(f).st_size;
     var unit = " b";
     if (file_size>1024) {
         file_size/=1024;