diff --git a/CMakeLists.txt b/CMakeLists.txt
index c45022b..d2f7497 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -39,7 +39,6 @@ set(NASAL_OBJECT_SOURCE_FILE
     ${CMAKE_SOURCE_DIR}/src/nasal_gc.cpp
     ${CMAKE_SOURCE_DIR}/src/nasal_import.cpp
     ${CMAKE_SOURCE_DIR}/src/nasal_lexer.cpp
-    ${CMAKE_SOURCE_DIR}/src/nasal_misc.cpp
     ${CMAKE_SOURCE_DIR}/src/nasal_opcode.cpp
     ${CMAKE_SOURCE_DIR}/src/nasal_parse.cpp
     ${CMAKE_SOURCE_DIR}/src/nasal_type.cpp
diff --git a/makefile b/makefile
index ffbf9ad..698e9c2 100644
--- a/makefile
+++ b/makefile
@@ -54,7 +54,6 @@ NASAL_OBJECT = \
 	build/nasal_opcode.o\
 	build/symbol_finder.o\
 	build/nasal_codegen.o\
-	build/nasal_misc.o\
 	build/nasal_gc.o\
 	build/builtin.o\
 	build/fg_props.o\
@@ -92,9 +91,6 @@ build:
 build/main.o: $(NASAL_HEADER) src/main.cpp | build
 	$(CXX) $(CXXFLAGS) src/main.cpp -o build/main.o
 
-build/nasal_misc.o: src/nasal.h src/util/util.h src/nasal_misc.cpp | build
-	$(CXX) $(CXXFLAGS) src/nasal_misc.cpp -o build/nasal_misc.o
-
 build/cli.o: src/cli/cli.h src/cli/cli.cpp | build
 	$(CXX) $(CXXFLAGS) src/cli/cli.cpp -o build/cli.o
 
@@ -110,7 +106,10 @@ build/repl.o: $(NASAL_HEADER) src/repl/repl.h src/repl/repl.cpp | build
 build/nasal_err.o: src/nasal.h src/repl/repl.h src/nasal_err.h src/nasal_err.cpp | build
 	$(CXX) $(CXXFLAGS) src/nasal_err.cpp -o build/nasal_err.o
 
-build/nasal_type.o: src/nasal.h src/nasal_type.h src/nasal_type.cpp | build
+build/nasal_type.o:\
+	src/nasal.h\
+	src/util/util.h\
+	src/nasal_type.h src/nasal_type.cpp | build
 	$(CXX) $(CXXFLAGS) src/nasal_type.cpp -o build/nasal_type.o
 
 build/nasal_gc.o: src/nasal.h src/nasal_type.h src/nasal_gc.h src/nasal_gc.cpp | build
@@ -129,6 +128,7 @@ build/nasal_import.o: \
 build/nasal_lexer.o: \
 	src/nasal.h\
 	src/repl/repl.h\
+	src/util/util.h\
 	src/util/fs.h\
 	src/nasal_err.h\
 	src/nasal_lexer.h src/nasal_lexer.cpp | build
@@ -163,7 +163,6 @@ build/bits_lib.o: \
 	src/natives/bits_lib.h src/natives/bits_lib.cpp | build
 	$(CXX) $(CXXFLAGS) src/natives/bits_lib.cpp -o build/bits_lib.o
 
-
 build/math_lib.o: \
 	src/nasal.h\
 	src/nasal_type.h\
@@ -190,6 +189,7 @@ build/json_lib.o: \
 	src/nasal.h\
 	src/nasal_type.h\
 	src/nasal_gc.h\
+	src/util/util.h\
 	src/natives/json_lib.h src/natives/json_lib.cpp | build
 	$(CXX) $(CXXFLAGS) src/natives/json_lib.cpp -o build/json_lib.o
 
@@ -220,6 +220,7 @@ build/nasal_codegen.o: $(NASAL_HEADER) src/nasal_codegen.h src/nasal_codegen.cpp
 build/nasal_opcode.o: \
 	src/nasal.h\
 	src/natives/builtin.h\
+	src/util/util.h\
 	src/nasal_opcode.h src/nasal_opcode.cpp | build
 	$(CXX) $(CXXFLAGS) src/nasal_opcode.cpp -o build/nasal_opcode.o
 
@@ -228,6 +229,7 @@ build/nasal_parse.o: \
 	src/nasal_ast.h\
 	src/nasal_lexer.h\
 	src/nasal_err.h\
+	src/util/util.h\
 	src/nasal_parse.h src/nasal_parse.cpp src/nasal_ast.h | build
 	$(CXX) $(CXXFLAGS) src/nasal_parse.cpp -o build/nasal_parse.o
 
@@ -259,6 +261,7 @@ build/ast_dumper.o: \
 	src/nasal_err.h\
 	src/nasal_ast.h\
 	src/ast_visitor.h\
+	src/util/util.h\
 	src/ast_dumper.h src/ast_dumper.cpp | build
 	$(CXX) $(CXXFLAGS) src/ast_dumper.cpp -o build/ast_dumper.o
 
diff --git a/src/ast_dumper.cpp b/src/ast_dumper.cpp
index a12a0e7..03fbb71 100644
--- a/src/ast_dumper.cpp
+++ b/src/ast_dumper.cpp
@@ -1,4 +1,5 @@
 #include "ast_dumper.h"
+#include "util/util.h"
 
 #include <iostream>
 
@@ -39,7 +40,7 @@ bool ast_dumper::visit_number_literal(number_literal* node) {
 
 bool ast_dumper::visit_string_literal(string_literal* node) {
     dump_indent();
-    std::cout << "string \"" << rawstr(node->get_content()) << "\"";
+    std::cout << "string \"" << util::rawstr(node->get_content()) << "\"";
     std::cout << format_location(node);
     return true;
 }
diff --git a/src/nasal.h b/src/nasal.h
index 7d0c256..a324ad5 100644
--- a/src/nasal.h
+++ b/src/nasal.h
@@ -5,11 +5,6 @@
 #endif
 
 #include <cstdint>
-#include <iostream>
-#include <fstream>
-#include <cstring>
-#include <sstream>
-#include <cmath>
 
 // abbreviation of some useful basic type
 using i32 = std::int32_t;
@@ -21,24 +16,5 @@ using u64 = std::uint64_t;
 using usize = std::size_t;
 using f64 = double;
 
-namespace nasal {
-
 // virtual machine stack depth, both global depth and value stack depth
 const u32 VM_STACK_DEPTH = UINT16_MAX;
-
-f64 hex_to_f64(const char*);
-f64 oct_to_f64(const char*);
-// we have the same reason not using atof here
-// just as andy's interpreter does.
-// 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.
-f64 dec_to_f64(const char*);
-
-f64 str_to_num(const char*);
-i32 utf8_hdchk(const char);
-std::string char_to_hex(const char);
-std::string rawstr(const std::string&, const usize maxlen = 0);
-
-}
\ No newline at end of file
diff --git a/src/nasal_codegen.cpp b/src/nasal_codegen.cpp
index 06f7ea9..2a0b3cc 100644
--- a/src/nasal_codegen.cpp
+++ b/src/nasal_codegen.cpp
@@ -1,4 +1,5 @@
 #include "nasal_codegen.h"
+#include "util/util.h"
 
 namespace nasal {
 
@@ -1390,7 +1391,7 @@ void codegen::print(std::ostream& out) {
 
     // print const strings
     for(const auto& str : const_string_table) {
-        out << "  .symbol \"" << rawstr(str) << "\"\n";
+        out << "  .symbol \"" << util::rawstr(str) << "\"\n";
     }
     
     // print blank line
diff --git a/src/nasal_gc.h b/src/nasal_gc.h
index 7acfa57..399773e 100644
--- a/src/nasal_gc.h
+++ b/src/nasal_gc.h
@@ -13,6 +13,7 @@
 #include <thread>
 #include <cstring>
 #include <sstream>
+#include <iostream>
 
 #include "nasal.h"
 #include "nasal_type.h"
diff --git a/src/nasal_lexer.cpp b/src/nasal_lexer.cpp
index f98be38..7ff1f21 100644
--- a/src/nasal_lexer.cpp
+++ b/src/nasal_lexer.cpp
@@ -6,6 +6,7 @@
 
 #include "nasal_lexer.h"
 #include "repl/repl.h"
+#include "util/util.h"
 #include "util/fs.h"
 
 namespace nasal {
@@ -62,7 +63,7 @@ void lexer::err_char() {
     char c = res[ptr++];
     err.err("lexer",
         {line, column-1, line, column, filename},
-        "invalid character 0x" + char_to_hex(c)
+        "invalid character 0x" + util::char_to_hex(c)
     );
     ++invalid_char;
 }
@@ -109,7 +110,7 @@ std::string lexer::utf8_gen() {
     std::string str = "";
     while(ptr<res.size() && res[ptr]<0) {
         std::string tmp = "";
-        u32 nbytes = utf8_hdchk(res[ptr]);
+        u32 nbytes = util::utf8_hdchk(res[ptr]);
         if (!nbytes) {
             ++ptr;
             ++column;
@@ -126,9 +127,9 @@ std::string lexer::utf8_gen() {
         // utf8 character's total length is 1+nbytes
         if (tmp.length()!=1+nbytes) {
             ++column;
-            std::string utf_info = "0x" + char_to_hex(tmp[0]);
+            std::string utf_info = "0x" + util::char_to_hex(tmp[0]);
             for(u32 i = 1; i<tmp.size(); ++i) {
-                utf_info += " 0x" + char_to_hex(tmp[i]);
+                utf_info += " 0x" + util::char_to_hex(tmp[i]);
             }
             err.err("lexer",
                 {line, column-1, line, column, filename},
@@ -319,7 +320,7 @@ token lexer::str_gen() {
     ++column;
 
     // if is not utf8, 1+utf8_hdchk should be 1
-    if (begin=='`' && str.length()!=1+utf8_hdchk(str[0])) {
+    if (begin=='`' && str.length()!=1+util::utf8_hdchk(str[0])) {
         err.err("lexer",
             {begin_line, begin_column, line, column, filename},
             "\'`\' is used for string including one character"
diff --git a/src/nasal_misc.cpp b/src/nasal_misc.cpp
deleted file mode 100644
index 4702e01..0000000
--- a/src/nasal_misc.cpp
+++ /dev/null
@@ -1,154 +0,0 @@
-#include "nasal.h"
-#include "util/util.h"
-
-namespace nasal {
-
-f64 hex_to_f64(const char* str) {
-    f64 ret = 0;
-    for(; *str; ++str) {
-        if ('0'<=*str && *str<='9') {
-            ret = ret*16+(*str-'0');
-        } else if ('a'<=*str && *str<='f') {
-            ret = ret*16+(*str-'a'+10);
-        } else if ('A'<=*str && *str<='F') {
-            ret = ret*16+(*str-'A'+10);
-        } else {
-            return nan("");
-        }
-    }
-    return ret;
-}
-
-f64 oct_to_f64(const char* str) {
-    f64 ret = 0;
-    while('0'<=*str && *str<'8') {
-        ret = ret*8+(*str++-'0');
-    }
-    if (*str) {
-        return nan("");
-    }
-    return ret;
-}
-
-// we have the same reason not using atof here
-// just as andy's interpreter does.
-// 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.
-f64 dec_to_f64(const char* str) {
-    f64 ret = 0, num_pow = 0;
-    bool negative = false;
-    while('0'<=*str && *str<='9') {
-        ret = ret*10+(*str++-'0');
-    }
-    if (!*str) {
-        return ret;
-    }
-    if (*str=='.') {
-        if (!*++str) {
-            return nan("");
-        }
-        num_pow = 0.1;
-        while('0'<=*str && *str<='9') {
-            ret += num_pow*(*str++-'0');
-            num_pow *= 0.1;
-        }
-        if (!*str) {
-            return ret;
-        }
-    }
-    if (*str!='e' && *str!='E') {
-        return nan("");
-    }
-    if (!*++str) {
-        return nan("");
-    }
-    if (*str=='-' || *str=='+') {
-        negative = (*str++=='-');
-    }
-    if (!*str) {
-        return nan("");
-    }
-    num_pow = 0;
-    while('0'<=*str && *str<='9') {
-        num_pow = num_pow*10+(*str++-'0');
-    }
-    if (*str) {
-        return nan("");
-    }
-    return negative?
-        ret*std::pow(10, 1-num_pow)*0.1:
-        ret*std::pow(10, num_pow-1)*10;
-}
-
-f64 str_to_num(const char* str) {
-    bool negative = false;
-    f64 res = 0;
-    if (*str=='-' || *str=='+') {
-        negative = (*str++=='-');
-    }
-    if (!*str) {
-        return nan("");
-    }
-    if (str[0]=='0' && str[1]=='x') {
-        res = hex_to_f64(str+2);
-    } else if (str[0]=='0' && str[1]=='o') {
-        res = oct_to_f64(str+2);
-    } else {
-        res = dec_to_f64(str);
-    }
-    return negative? -res:res;
-}
-
-i32 utf8_hdchk(const char head) {
-    // RFC-2279 but now we use RFC-3629 so nbytes is less than 4
-    const auto c = static_cast<u8>(head);
-    if ((c>>5)==0x06) { // 110x xxxx (10xx xxxx)^1
-        return 1;
-    }
-    if ((c>>4)==0x0e) { // 1110 xxxx (10xx xxxx)^2
-        return 2;
-    }
-    if ((c>>3)==0x1e) { // 1111 0xxx (10xx xxxx)^3
-        return 3;
-    }
-    return 0;
-}
-
-std::string char_to_hex(const char c) {
-    const char hextbl[] = "0123456789abcdef";
-    return {hextbl[(c&0xf0)>>4], hextbl[c&0x0f]};
-}
-
-std::string rawstr(const std::string& str, const usize maxlen) {
-    std::string ret("");
-    for(auto i : str) {
-        // windows doesn't output unicode normally, so we output the hex
-        if (util::is_windows() && i<=0) {
-            ret += "\\x" + char_to_hex(i);
-            continue;
-        }
-        switch(i) {
-            case '\0':  ret += "\\0";  break;
-            case '\a':  ret += "\\a";  break;
-            case '\b':  ret += "\\b";  break;
-            case '\t':  ret += "\\t";  break;
-            case '\n':  ret += "\\n";  break;
-            case '\v':  ret += "\\v";  break;
-            case '\f':  ret += "\\f";  break;
-            case '\r':  ret += "\\r";  break;
-            case '\033':ret += "\\e";  break;
-            case '\"':  ret += "\\\""; break;
-            case '\'':  ret += "\\\'"; break;
-            case '\\':  ret += "\\\\"; break;
-            default:    ret += i;      break;
-        }
-    }
-    if (maxlen && ret.length()>maxlen) {
-        ret = ret.substr(0, maxlen)+"...";
-    }
-    return ret;
-}
-
-}
diff --git a/src/nasal_opcode.cpp b/src/nasal_opcode.cpp
index 80a3439..b8ed77d 100644
--- a/src/nasal_opcode.cpp
+++ b/src/nasal_opcode.cpp
@@ -1,4 +1,5 @@
 #include "nasal_opcode.h"
+#include "util/util.h"
 
 namespace nasal {
 
@@ -80,7 +81,7 @@ void codestream::dump(std::ostream& out) const {
             break;
         case op_lnkeqc:
             out << hex << "0x" << num << dec;
-            out << " (" << rawstr(const_string[num], 16) << ")";
+            out << " (" << util::rawstr(const_string[num], 16) << ")";
             break;
         case op_addecp:
         case op_subecp:
@@ -91,7 +92,7 @@ void codestream::dump(std::ostream& out) const {
             break;
         case op_lnkecp:
             out << hex << "0x" << num << dec;
-            out << " (" << rawstr(const_string[num], 16) << ") sp-1";
+            out << " (" << util::rawstr(const_string[num], 16) << ") sp-1";
             break;
         case op_addc:
         case op_subc:
@@ -141,7 +142,7 @@ void codestream::dump(std::ostream& out) const {
         case op_deft:
         case op_dyn:
             out << hex << "0x" << num << dec;
-            out << " (" << rawstr(const_string[num], 16) << ")";
+            out << " (" << util::rawstr(const_string[num], 16) << ")";
             break;
         default:
             if (files) {
diff --git a/src/nasal_parse.cpp b/src/nasal_parse.cpp
index e3628e6..811c6ce 100644
--- a/src/nasal_parse.cpp
+++ b/src/nasal_parse.cpp
@@ -1,5 +1,6 @@
 #include "nasal_ast.h"
 #include "nasal_parse.h"
+#include "util/util.h"
 
 namespace nasal {
 
@@ -227,8 +228,10 @@ nil_expr* parse::nil() {
 }
 
 number_literal* parse::num() {
-    auto node = new number_literal(toks[ptr].loc,
-        str_to_num(toks[ptr].str.c_str()));
+    auto node = new number_literal(
+        toks[ptr].loc,
+        util::str_to_num(toks[ptr].str.c_str())
+    );
     match(tok::tk_num);
     return node;
 }
diff --git a/src/nasal_type.cpp b/src/nasal_type.cpp
index cdb6b38..c163541 100644
--- a/src/nasal_type.cpp
+++ b/src/nasal_type.cpp
@@ -1,4 +1,5 @@
 #include "nasal_type.h"
+#include "util/util.h"
 
 #include <cstring>
 #include <sstream>
@@ -268,7 +269,7 @@ void nas_val::clear() {
 }
 
 f64 var::to_num() {
-    return type!=vm_type::vm_str? val.num:str_to_num(str().c_str());
+    return type!=vm_type::vm_str? val.num:util::str_to_num(str().c_str());
 }
 
 std::string var::to_str() {
diff --git a/src/nasal_type.h b/src/nasal_type.h
index 499befc..208babb 100644
--- a/src/nasal_type.h
+++ b/src/nasal_type.h
@@ -2,6 +2,9 @@
 
 #include "nasal.h"
 
+#include <cstring>
+#include <sstream>
+#include <iostream>
 #include <vector>
 #include <unordered_map>
 
diff --git a/src/nasal_vm.cpp b/src/nasal_vm.cpp
index abf9454..9515c1a 100644
--- a/src/nasal_vm.cpp
+++ b/src/nasal_vm.cpp
@@ -1,4 +1,5 @@
 #include "nasal_vm.h"
+#include "util/util.h"
 
 namespace nasal {
 
@@ -75,7 +76,7 @@ void vm::value_info(var& val) {
         case vm_type::vm_nil:  std::clog << "| nil  |"; break;
         case vm_type::vm_num:  std::clog << "| num  | " << val.num(); break;
         case vm_type::vm_str:  std::clog << "| str  | <0x" << std::hex << p
-                                         << "> \"" << rawstr(val.str(), 16)
+                                         << "> \"" << util::rawstr(val.str(), 16)
                                          << "\"" << std::dec; break;
         case vm_type::vm_func: std::clog << "| func | <0x" << std::hex << p
                                          << std::dec << "> " << val.func();
diff --git a/src/nasal_vm.h b/src/nasal_vm.h
index 2553481..8ed1109 100644
--- a/src/nasal_vm.h
+++ b/src/nasal_vm.h
@@ -8,6 +8,7 @@
 #include "nasal_import.h"
 #include "nasal_gc.h"
 #include "nasal_codegen.h"
+#include "util/util.h"
 
 #ifdef _MSC_VER
 #pragma warning (disable:4244)
@@ -216,7 +217,7 @@ inline bool vm::cond(var& val) {
     if (val.is_num()) {
         return val.num();
     } else if (val.is_str()) {
-        const f64 num = str_to_num(val.str().c_str());
+        const f64 num = util::str_to_num(val.str().c_str());
         return std::isnan(num)? !val.str().empty():num;
     }
     return false;
@@ -333,7 +334,7 @@ inline void vm::o_lnot() {
         case vm_type::vm_nil: ctx.top[0] = one; break;
         case vm_type::vm_num: ctx.top[0] = val.num()? zero:one; break;
         case vm_type::vm_str: {
-            const f64 num = str_to_num(val.str().c_str());
+            const f64 num = util::str_to_num(val.str().c_str());
             if (std::isnan(num)) {
                 ctx.top[0] = var::num(static_cast<f64>(val.str().empty()));
             } else {
diff --git a/src/natives/io_lib.cpp b/src/natives/io_lib.cpp
index 389a6a5..c5efb0b 100644
--- a/src/natives/io_lib.cpp
+++ b/src/natives/io_lib.cpp
@@ -1,6 +1,7 @@
 #include "natives/io_lib.h"
 #include "util/fs.h"
 
+#include <fstream>
 #include <sys/stat.h>
 
 namespace nasal {
diff --git a/src/natives/json_lib.cpp b/src/natives/json_lib.cpp
index e32cbfc..719120c 100644
--- a/src/natives/json_lib.cpp
+++ b/src/natives/json_lib.cpp
@@ -1,4 +1,5 @@
 #include "natives/json_lib.h"
+#include "util/util.h"
 
 #include <iostream>
 #include <cstring>
@@ -170,7 +171,7 @@ void json::next() {
         } else if (text[ptr]!=' ' && text[ptr]!='\t' && text[ptr]!='\r') {
             error_info() += "json::parse: line " + std::to_string(line);
             error_info() += ": invalid character `0x";
-            error_info() += char_to_hex(text[ptr]);
+            error_info() += util::char_to_hex(text[ptr]);
             error_info() += "`\n";
         }
         ++ptr;
@@ -253,7 +254,7 @@ void json::vector_member(nas_vec& vec, gc* ngc) {
         vec.elems.push_back(ngc->newstr(this_token.content));
         next();
     } else if (this_token.type==json_token_type::tok_num) {
-        vec.elems.push_back(var::num(str_to_num(this_token.content.c_str())));
+        vec.elems.push_back(var::num(util::str_to_num(this_token.content.c_str())));
         next();
     }
 }
@@ -292,7 +293,7 @@ void json::hash_member(nas_hash& hash, gc* ngc) {
         hash.elems.insert({name, ngc->newstr(this_token.content)});
         next();
     } else if (this_token.type==json_token_type::tok_num) {
-        hash.elems.insert({name, var::num(str_to_num(this_token.content.c_str()))});
+        hash.elems.insert({name, var::num(util::str_to_num(this_token.content.c_str()))});
         next();
     }
 }
diff --git a/src/util/util.cpp b/src/util/util.cpp
index cf027fc..95dc052 100644
--- a/src/util/util.cpp
+++ b/src/util/util.cpp
@@ -1,5 +1,7 @@
 #include "util/util.h"
 
+#include <cmath>
+
 namespace nasal::util {
 
 bool is_windows() {
@@ -118,4 +120,152 @@ const char* get_arch() {
     return "unknown";
 }
 
+u32 utf8_hdchk(const char head) {
+    // RFC-2279 but now we use RFC-3629 so nbytes is less than 4
+    const auto c = static_cast<u8>(head);
+    if ((c>>5)==0x06) { // 110x xxxx (10xx xxxx)^1
+        return 1;
+    }
+    if ((c>>4)==0x0e) { // 1110 xxxx (10xx xxxx)^2
+        return 2;
+    }
+    if ((c>>3)==0x1e) { // 1111 0xxx (10xx xxxx)^3
+        return 3;
+    }
+    return 0;
+}
+
+std::string char_to_hex(const char c) {
+    const char hextbl[] = "0123456789abcdef";
+    return {hextbl[(c&0xf0)>>4], hextbl[c&0x0f]};
+}
+
+std::string rawstr(const std::string& str, const usize maxlen) {
+    std::string ret("");
+    for(auto i : str) {
+        // windows doesn't output unicode normally, so we output the hex
+        if (util::is_windows() && i<=0) {
+            ret += "\\x" + char_to_hex(i);
+            continue;
+        }
+        switch(i) {
+            case '\0':  ret += "\\0";  break;
+            case '\a':  ret += "\\a";  break;
+            case '\b':  ret += "\\b";  break;
+            case '\t':  ret += "\\t";  break;
+            case '\n':  ret += "\\n";  break;
+            case '\v':  ret += "\\v";  break;
+            case '\f':  ret += "\\f";  break;
+            case '\r':  ret += "\\r";  break;
+            case '\033':ret += "\\e";  break;
+            case '\"':  ret += "\\\""; break;
+            case '\'':  ret += "\\\'"; break;
+            case '\\':  ret += "\\\\"; break;
+            default:    ret += i;      break;
+        }
+    }
+    if (maxlen && ret.length()>maxlen) {
+        ret = ret.substr(0, maxlen)+"...";
+    }
+    return ret;
+}
+
+f64 hex_to_f64(const char* str) {
+    f64 ret = 0;
+    for(; *str; ++str) {
+        if ('0'<=*str && *str<='9') {
+            ret = ret*16+(*str-'0');
+        } else if ('a'<=*str && *str<='f') {
+            ret = ret*16+(*str-'a'+10);
+        } else if ('A'<=*str && *str<='F') {
+            ret = ret*16+(*str-'A'+10);
+        } else {
+            return nan("");
+        }
+    }
+    return ret;
+}
+
+f64 oct_to_f64(const char* str) {
+    f64 ret = 0;
+    while('0'<=*str && *str<'8') {
+        ret = ret*8+(*str++-'0');
+    }
+    if (*str) {
+        return nan("");
+    }
+    return ret;
+}
+
+// we have the same reason not using atof here
+// just as andy's interpreter does.
+// 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.
+f64 dec_to_f64(const char* str) {
+    f64 ret = 0, num_pow = 0;
+    bool negative = false;
+    while('0'<=*str && *str<='9') {
+        ret = ret*10+(*str++-'0');
+    }
+    if (!*str) {
+        return ret;
+    }
+    if (*str=='.') {
+        if (!*++str) {
+            return nan("");
+        }
+        num_pow = 0.1;
+        while('0'<=*str && *str<='9') {
+            ret += num_pow*(*str++-'0');
+            num_pow *= 0.1;
+        }
+        if (!*str) {
+            return ret;
+        }
+    }
+    if (*str!='e' && *str!='E') {
+        return nan("");
+    }
+    if (!*++str) {
+        return nan("");
+    }
+    if (*str=='-' || *str=='+') {
+        negative = (*str++=='-');
+    }
+    if (!*str) {
+        return nan("");
+    }
+    num_pow = 0;
+    while('0'<=*str && *str<='9') {
+        num_pow = num_pow*10+(*str++-'0');
+    }
+    if (*str) {
+        return nan("");
+    }
+    return negative?
+        ret*std::pow(10, 1-num_pow)*0.1:
+        ret*std::pow(10, num_pow-1)*10;
+}
+
+f64 str_to_num(const char* str) {
+    bool negative = false;
+    f64 res = 0;
+    if (*str=='-' || *str=='+') {
+        negative = (*str++=='-');
+    }
+    if (!*str) {
+        return nan("");
+    }
+    if (str[0]=='0' && str[1]=='x') {
+        res = hex_to_f64(str+2);
+    } else if (str[0]=='0' && str[1]=='o') {
+        res = oct_to_f64(str+2);
+    } else {
+        res = dec_to_f64(str);
+    }
+    return negative? -res:res;
+}
+
 }
\ No newline at end of file
diff --git a/src/util/util.h b/src/util/util.h
index 551b264..4ab673e 100644
--- a/src/util/util.h
+++ b/src/util/util.h
@@ -1,4 +1,9 @@
-#pragma
+#pragma once
+
+#include "nasal.h"
+
+#include <cstring>
+#include <sstream>
 
 namespace nasal::util {
 
@@ -16,4 +21,21 @@ bool is_superh();
 const char* get_platform();
 const char* get_arch();
 
+u32 utf8_hdchk(const char);
+
+std::string char_to_hex(const char);
+std::string rawstr(const std::string&, const usize maxlen = 0);
+
+f64 hex_to_f64(const char*);
+f64 oct_to_f64(const char*);
+// we have the same reason not using atof here
+// just as andy's interpreter does.
+// 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.
+f64 dec_to_f64(const char*);
+
+f64 str_to_num(const char*);
+
 }
\ No newline at end of file