diff --git a/ast/nasal_new_ast.cpp b/ast/nasal_new_ast.cpp
index 8a5ef5c..b487fe4 100644
--- a/ast/nasal_new_ast.cpp
+++ b/ast/nasal_new_ast.cpp
@@ -57,4 +57,302 @@ hash_pair::~hash_pair() {
 
 void hash_pair::accept(ast_visitor* visitor) {
     visitor->visit_hash_pair(this);
+}
+
+function::~function() {
+    for(auto i : parameter_list) {
+        delete i;
+    }
+    if (block) {
+        delete block;
+    }
+}
+
+void function::accept(ast_visitor* visitor) {
+    // TODO
+}
+
+code_block::~code_block() {
+    for(auto i : expressions) {
+        delete i;
+    }
+}
+
+void code_block::accept(ast_visitor* visitor) {
+    // TODO
+}
+
+parameter::~parameter() {
+    if (name) {
+        delete name;
+    }
+    if (default_value) {
+        delete default_value;
+    }
+}
+
+void parameter::accept(ast_visitor* visitor) {
+    // TODO
+}
+
+ternary_operator::~ternary_operator() {
+    if (condition) {
+        delete condition;
+    }
+    if (left) {
+        delete left;
+    }
+    if (right) {
+        delete right;
+    }
+}
+
+void ternary_operator::accept(ast_visitor* visitor) {
+    // TODO
+}
+
+binary_operator::~binary_operator() {
+    if (left) {
+        delete left;
+    }
+    if (right) {
+        delete right;
+    }
+}
+
+void binary_operator::accept(ast_visitor* visitor) {
+    // TODO
+}
+
+unary_operator::~unary_operator() {
+    if (value) {
+        delete value;
+    }
+}
+
+void unary_operator::accept(ast_visitor* visitor) {
+    // TODO
+}
+
+call_expr::~call_expr() {
+    if(first) {
+        delete first;
+    }
+    for(auto i : calls) {
+        delete i;
+    }
+}
+
+void call_expr::accept(ast_visitor* visitor) {
+    // TODO
+}
+
+void call_hash::accept(ast_visitor* visitor) {
+    // TODO
+}
+
+call_vector::~call_vector() {
+    for(auto i : calls) {
+        delete i;
+    }
+}
+
+void call_vector::accept(ast_visitor* visitor) {
+    // TODO
+}
+
+call_function::~call_function() {
+    for(auto i : args) {
+        delete i;
+    }
+}
+
+void call_function::accept(ast_visitor* visitor) {
+    // TODO
+}
+
+slice_vector::~slice_vector() {
+    if (begin) {
+        delete begin;
+    }
+    if (end) {
+        delete end;
+    }
+}
+
+void slice_vector::accept(ast_visitor* visitor) {
+    // TODO
+}
+
+definition_expr::~definition_expr() {
+    if (variable_name) {
+        delete variable_name;
+    }
+    if (variables) {
+        delete variables;
+    }
+    if (value) {
+        delete value;
+    }
+}
+
+void definition_expr::accept(ast_visitor* visitor) {
+    // TODO
+}
+
+assignment_expr::~assignment_expr() {
+    if (left) {
+        delete left;
+    }
+    if (right) {
+        delete right;
+    }
+}
+
+void assignment_expr::accept(ast_visitor* visitor) {
+    // TODO
+}
+
+multi_define::~multi_define() {
+    for(auto i : variables) {
+        delete i;
+    }
+    if (value) {
+        delete value;
+    }
+}
+
+void multi_define::accept(ast_visitor* visitor) {
+    // TODO
+}
+
+tuple_expr::~tuple_expr() {
+    for(auto i : elements) {
+        delete i;
+    }
+}
+
+void tuple_expr::accept(ast_visitor* visitor) {
+    // TODO
+}
+
+multi_assign::~multi_assign() {
+    if (left) {
+        delete left;
+    }
+    if (right) {
+        delete right;
+    }
+}
+
+void multi_assign::accept(ast_visitor* visitor) {
+    // TODO
+}
+
+while_expr::~while_expr() {
+    if (condition) {
+        delete condition;
+    }
+    if (block) {
+        delete block;
+    }
+}
+
+void while_expr::accept(ast_visitor* visitor) {
+    // TODO
+}
+
+for_expr::~for_expr() {
+    if (initializing) {
+        delete initializing;
+    }
+    if (condition) {
+        delete condition;
+    }
+    if (step) {
+        delete step;
+    }
+    if (block) {
+        delete block;
+    }
+}
+
+void for_expr::accept(ast_visitor* visitor) {
+    // TODO
+}
+
+iter_expr::~iter_expr() {
+    if (name) {
+        delete name;
+    }
+    if (call) {
+        delete call;
+    }
+}
+
+void iter_expr::accept(ast_visitor* visitor) {
+    // TODO
+}
+
+forei_expr::~forei_expr() {
+    if (iterator) {
+        delete iterator;
+    }
+    if (vector_node) {
+        delete vector_node;
+    }
+    if (block) {
+        delete block;
+    }
+}
+
+void forei_expr::accept(ast_visitor* visitor) {
+    // TODO
+}
+
+condition_expr::~condition_expr() {
+    if (if_stmt) {
+        delete if_stmt;
+    }
+    for(auto i : elsif_stmt) {
+        delete i;
+    }
+    if (else_stmt) {
+        delete else_stmt;
+    }
+}
+
+void condition_expr::accept(ast_visitor* visitor) {
+    // TODO
+}
+
+if_expr::~if_expr() {
+    if (condition) {
+        delete condition;
+    }
+    if (block) {
+        delete block;
+    }
+}
+
+void if_expr::accept(ast_visitor* visitor) {
+    // TODO
+}
+
+void continue_expr::accept(ast_visitor* visitor) {
+    // TODO
+}
+
+void break_expr::accept(ast_visitor* visitor) {
+    // TODO
+}
+
+return_expr::~return_expr() {
+    if (value) {
+        delete value;
+    }
+}
+
+void return_expr::accept(ast_visitor* visitor) {
+    // TODO
 }
\ No newline at end of file
diff --git a/ast/nasal_new_ast.h b/ast/nasal_new_ast.h
index ab38ba4..2de3937 100644
--- a/ast/nasal_new_ast.h
+++ b/ast/nasal_new_ast.h
@@ -1,7 +1,7 @@
 #pragma once
 
-#include "nasal.h"
-#include "nasal_err.h"
+#include "nasal_new_header.h"
+#include "nasal_new_err.h"
 
 #include <vector>
 #include <unordered_map>
@@ -51,6 +51,7 @@ enum class expr_type:u32 {
     ast_multi_id,    // multi identifiers sub-tree
     ast_tuple,
     ast_def,         // definition
+    ast_assign,
     ast_multi_assign,
     ast_continue,    // continue keyword, only used in loop
     ast_break,       // break keyword, only used in loop
@@ -88,7 +89,7 @@ public:
         nd_loc.end_line = location.end_line;
         nd_loc.end_column = location.end_column;
     }
-    virtual void accept(ast_visitor*);
+    void accept(ast_visitor*);
 };
 
 class null_expr:public expr {
@@ -115,6 +116,7 @@ public:
     number_literal(const span& location, const f64 num):
         expr(location, expr_type::ast_num), number(num) {}
     ~number_literal() = default;
+    f64 get_number() const {return number;}
     void accept(ast_visitor*) override;
 };
 
@@ -126,6 +128,7 @@ public:
     string_literal(const span& location, const std::string& str):
         expr(location, expr_type::ast_str), content(str) {}
     ~string_literal() = default;
+    const std::string get_content() const {return content;}
     void accept(ast_visitor*) override;
 };
 
@@ -137,6 +140,7 @@ public:
     identifier(const span& location, const std::string& str):
         expr(location, expr_type::ast_id), name(str) {}
     ~identifier() = default;
+    const std::string get_name() const {return name;}
     void accept(ast_visitor*) override;
 };
 
@@ -346,7 +350,7 @@ public:
     call_hash(const span& location, const std::string& name):
         expr(location, expr_type::ast_callh),
         field(name) {}
-    ~call_hash();
+    ~call_hash() = default;
     void accept(ast_visitor*) override;
 };
 
@@ -405,6 +409,42 @@ public:
     void set_identifier(identifier* node) {variable_name = node;}
     void set_multi_define(multi_define* node) {variables = node;}
     void set_value(expr* node) {value = node;}
+
+    expr* get_value() {return value;}
+    void accept(ast_visitor*) override;
+};
+
+class assignment_expr:public expr {
+public:
+    enum class assign_type {
+        equal,
+        add_equal,
+        sub_equal,
+        mult_equal,
+        div_equal,
+        concat_equal,
+        bitwise_and_equal,
+        bitwise_or_equal,
+        bitwise_xor_equal
+    };
+
+private:
+    assign_type type;
+    expr* left;
+    expr* right;
+
+public:
+    assignment_expr(const span& location):
+        expr(location, expr_type::ast_assign),
+        left(nullptr), right(nullptr) {}
+    ~assignment_expr();
+    void set_type(assign_type operator_type) {type = operator_type;}
+    void set_left(expr* node) {left = node;}
+    void set_right(expr* node) {right = node;}
+
+    assign_type get_type() const {return type;}
+    expr* get_left() {return left;}
+    expr* get_right() {return right;}
     void accept(ast_visitor*) override;
 };
 
diff --git a/ast/nasal_new_err.cpp b/ast/nasal_new_err.cpp
new file mode 100644
index 0000000..7cf657d
--- /dev/null
+++ b/ast/nasal_new_err.cpp
@@ -0,0 +1,163 @@
+#include "nasal_new_err.h"
+
+std::ostream& back_white(std::ostream& s) {
+#ifdef _WIN32
+    SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), 0xf0);
+#else
+    s<<"\033[7m";
+#endif
+    return s;
+}
+
+std::ostream& red(std::ostream& s) {
+#ifdef _WIN32
+    SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), 0x0c);
+#else
+    s<<"\033[91;1m";
+#endif
+    return s;
+}
+
+std::ostream& cyan(std::ostream& s) {
+#ifdef _WIN32
+    SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), 0x03);
+#else
+    s<<"\033[36;1m";
+#endif
+    return s;
+}
+
+std::ostream& orange(std::ostream& s) {
+#ifdef _WIN32
+    SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), 0x0e);
+#else
+    s<<"\033[93;1m";
+#endif
+    return s;
+}
+
+std::ostream& white(std::ostream& s) {
+#ifdef _WIN32
+    SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), 0x0f);
+#else
+    s<<"\033[0m\033[1m";
+#endif
+    return s;
+}
+
+std::ostream& reset(std::ostream& s) {
+#ifdef _WIN32
+    SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), reset_ter_color.scr.wAttributes);
+#else
+    s<<"\033[0m";
+#endif
+    return s;
+}
+
+void flstream::load(const std::string& f) {
+    if (file==f) { // don't need to load a loaded file
+        return;
+    } else {
+        file=f;
+    }
+
+    res.clear();
+    std::ifstream in(f, std::ios::binary);
+    if (in.fail()) {
+        std::cerr<<red<<"src: "<<reset<<"cannot open <"<<f<<">\n";
+        std::exit(1);
+    }
+    
+    while(!in.eof()) {
+        std::string line;
+        std::getline(in, line);
+        res.push_back(line);
+    }
+}
+
+void error::fatal(const std::string& stage, const std::string& info) {
+    std::cerr<<red<<stage<<": "<<white<<info<<reset<<"\n";
+    if (file.length()) {
+        std::cerr<<cyan<<" --> "<<red<<file<<reset<<"\n\n";
+    } else {
+        std::cerr<<reset<<"\n";
+    }
+    std::exit(1);
+}
+
+void error::err(const std::string& stage, const std::string& info) {
+    ++cnt;
+    std::cerr<<red<<stage<<": "<<white<<info<<reset<<"\n";
+    if (file.length()) {
+        std::cerr<<cyan<<" --> "<<red<<file<<reset<<"\n\n";
+    } else {
+        std::cerr<<reset<<"\n";
+    }
+}
+
+void error::err(
+    const std::string& stage, const span& loc, const std::string& info) {
+    // load error occurred file into string lines
+    load(loc.file);
+
+    ++cnt;
+
+    std::cerr
+    <<red<<stage<<": "<<white<<info<<reset<<"\n"<<cyan<<"  --> "
+    <<red<<loc.file<<":"<<loc.begin_line<<":"<<loc.begin_column+1<<reset<<"\n";
+
+    const usize maxlen = std::to_string(loc.end_line).length();
+    const std::string iden = identation(maxlen);
+
+    for(u32 line=loc.begin_line; line<=loc.end_line; ++line) {
+        if (!line) {
+            continue;
+        }
+
+        if (loc.begin_line<line && line<loc.end_line) {
+            if (line==loc.begin_line+1) {
+                std::cerr<<cyan<<iden<<" | "<<reset<<"...\n"<<cyan<<iden<<" | "<<reset<<"\n";
+            }
+            continue;
+        }
+
+        // if this line has nothing, skip
+        if (!res[line-1].length() && line!=loc.end_line) {
+            continue;
+        }
+
+        const std::string& code=res[line-1];
+        std::cerr<<cyan<<leftpad(line, maxlen)<<" | "<<reset<<code<<"\n";
+        // output underline
+        std::cerr<<cyan<<iden<<" | "<<reset;
+        if (loc.begin_line==loc.end_line) {
+            for(u32 i=0; i<loc.begin_column; ++i) {
+                std::cerr<<char(" \t"[code[i]=='\t']);
+            }
+            for(u32 i=loc.begin_column ;i<loc.end_column; ++i) {
+                std::cerr<<red<<(code[i]=='\t'?"^^^^":"^")<<reset;
+            }
+        } else if (line==loc.begin_line) {
+            for(u32 i=0; i<loc.begin_column; ++i) {
+                std::cerr<<char(" \t"[code[i]=='\t']);
+            }
+            for(u32 i=loc.begin_column; i<code.size(); ++i) {
+                std::cerr<<red<<(code[i]=='\t'?"^^^^":"^")<<reset;
+            }
+        } else if (loc.begin_line<line && line<loc.end_line) {
+            for(u32 i=0; i<code.size(); ++i) {
+                std::cerr<<red<<(code[i]=='\t'?"^^^^":"^");
+            }
+        } else {
+            for(u32 i=0; i<loc.end_column; ++i) {
+                std::cerr<<red<<(code[i]=='\t'?"^^^^":"^");
+            }
+        }
+        if (line==loc.end_line) {
+            std::cerr<<reset;
+        } else {
+            std::cerr<<reset<<"\n";
+        }
+    }
+    std::cerr<<"\n\n";
+}
\ No newline at end of file
diff --git a/ast/nasal_new_err.h b/ast/nasal_new_err.h
new file mode 100644
index 0000000..192300b
--- /dev/null
+++ b/ast/nasal_new_err.h
@@ -0,0 +1,73 @@
+#pragma once
+
+#include <iostream>
+#include <fstream>
+#include <sstream> // MSVC need this to use std::getline
+#include <cstring>
+#include <vector>
+
+#include "nasal_new_header.h"
+
+struct span {
+    u32 begin_line;
+    u32 begin_column;
+    u32 end_line;
+    u32 end_column;
+    std::string file;
+};
+
+#ifdef _WIN32
+#include <windows.h> // use SetConsoleTextAttribute
+struct for_reset {
+    CONSOLE_SCREEN_BUFFER_INFO scr;
+    for_reset() {
+        GetConsoleScreenBufferInfo(GetStdHandle(STD_OUTPUT_HANDLE), &scr);
+    }
+} reset_ter_color;
+#endif
+
+std::ostream& back_white(std::ostream&);
+std::ostream& red(std::ostream&);
+std::ostream& cyan(std::ostream&);
+std::ostream& orange(std::ostream&);
+std::ostream& white(std::ostream&);
+std::ostream& reset(std::ostream&);
+
+class flstream {
+protected:
+    std::string file;
+    std::vector<std::string> res;
+public:
+    flstream():file("") {}
+    void load(const std::string&);
+    const std::string& operator[](usize n) const {return res[n];}
+    const std::string& name() const {return file;}
+    usize size() const {return res.size();}
+};
+
+class error:public flstream {
+private:
+    u32 cnt; // counter for errors
+
+    std::string identation(usize len) {
+        return std::string(len,' ');
+    }
+    std::string leftpad(u32 num, usize len) {
+        auto tmp = std::to_string(num);
+        while(tmp.length()<len) {
+            tmp=" "+tmp;
+        }
+        return tmp;
+    }
+public:
+    error():cnt(0) {}
+    void fatal(const std::string&, const std::string&);
+    void err(const std::string&, const std::string&);
+    void err(const std::string&, const span&, const std::string&);
+
+    void chkerr() const {
+        if (cnt) {
+            std::exit(1);
+        }
+    }
+};
diff --git a/ast/nasal_new_header.h b/ast/nasal_new_header.h
new file mode 100644
index 0000000..4b67fe4
--- /dev/null
+++ b/ast/nasal_new_header.h
@@ -0,0 +1,51 @@
+#pragma once
+
+#ifndef __nasver
+#define __nasver "10.1"
+#endif
+
+#include <cstdint>
+#include <iostream>
+#include <fstream>
+#include <cstring>
+#include <cmath>
+#include <vector>
+
+bool is_windows();
+bool is_linux();
+bool is_macos();
+bool is_x86();
+bool is_amd64();
+bool is_x86_64();
+bool is_arm();
+bool is_aarch64();
+bool is_ia64();
+bool is_powerpc();
+bool is_superh();
+
+using i32 = std::int32_t;
+using i64 = std::int64_t;
+using u8 = std::uint8_t;
+using u16 = std::uint16_t;
+using u32 = std::uint32_t;
+using u64 = std::uint64_t;
+using usize = std::size_t;
+using f64 = double;
+
+const u32 STACK_DEPTH=1024;
+
+f64 hex2f(const char*);
+f64 oct2f(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 dec2f(const char*);
+
+f64 str2num(const char*);
+i32 utf8_hdchk(const char);
+std::string chrhex(const char);
+std::string rawstr(const std::string&, const usize maxlen=0);
\ No newline at end of file
diff --git a/ast/nasal_new_lexer.cpp b/ast/nasal_new_lexer.cpp
index a476a91..3981794 100644
--- a/ast/nasal_new_lexer.cpp
+++ b/ast/nasal_new_lexer.cpp
@@ -59,7 +59,7 @@ void lexer::err_char() {
     err.fatal("lexer", "fatal error occurred, stop");
 }
 
-void lexer::open(const string& file) {
+void lexer::open(const std::string& file) {
     // check file exsits and it is a regular file
     struct stat buffer;
     if (stat(file.c_str(), &buffer)==0 && !S_ISREG(buffer.st_mode)) {
@@ -80,14 +80,14 @@ void lexer::open(const string& file) {
     res=ss.str();
 }
 
-tok lexer::get_type(const string& str) {
+tok lexer::get_type(const std::string& str) {
     return typetbl.count(str)?typetbl.at(str):tok::null;
 }
 
-string lexer::utf8_gen() {
-    string str="";
+std::string lexer::utf8_gen() {
+    std::string str="";
     while(ptr<res.size() && res[ptr]<0) {
-        string tmp="";
+        std::string tmp="";
         u32 nbytes=utf8_hdchk(res[ptr]);
         if (!nbytes) {
             ++ptr;
@@ -105,7 +105,7 @@ string lexer::utf8_gen() {
         // utf8 character's total length is 1+nbytes
         if (tmp.length()!=1+nbytes) {
             ++column;
-            string utf_info="0x"+chrhex(tmp[0]);
+            std::string utf_info="0x"+chrhex(tmp[0]);
             for(u32 i=1;i<tmp.size();++i) {
                 utf_info+=" 0x"+chrhex(tmp[i]);
             }
@@ -121,7 +121,7 @@ string lexer::utf8_gen() {
 token lexer::id_gen() {
     u32 begin_line=line;
     u32 begin_column=column;
-    string str="";
+    std::string str="";
     while(ptr<res.size() && (is_id(res[ptr])||is_dec(res[ptr]))) {
         if (res[ptr]<0) { // utf-8
             str+=utf8_gen();
@@ -139,7 +139,7 @@ token lexer::num_gen() {
     u32 begin_column=column;
     // generate hex number
     if (ptr+1<res.size() && res[ptr]=='0' && res[ptr+1]=='x') {
-        string str="0x";
+        std::string str="0x";
         ptr+=2;
         while(ptr<res.size() && is_hex(res[ptr])) {
             str+=res[ptr++];
@@ -150,7 +150,7 @@ token lexer::num_gen() {
         }
         return {{begin_line, begin_column, line, column, filename}, tok::num, str};
     } else if (ptr+1<res.size() && res[ptr]=='0' && res[ptr+1]=='o') { // generate oct number
-        string str="0o";
+        std::string str="0o";
         ptr+=2;
         while(ptr<res.size() && is_oct(res[ptr])) {
             str+=res[ptr++];
@@ -168,7 +168,7 @@ token lexer::num_gen() {
     }
     // generate dec number
     // dec number -> [0~9][0~9]*(.[0~9]*)(e|E(+|-)0|[1~9][0~9]*)
-    string str="";
+    std::string str="";
     while(ptr<res.size() && is_dec(res[ptr])) {
         str+=res[ptr++];
     }
@@ -206,7 +206,7 @@ token lexer::num_gen() {
 token lexer::str_gen() {
     u32 begin_line=line;
     u32 begin_column=column;
-    string str="";
+    std::string str="";
     const char begin=res[ptr];
     ++column;
     while(++ptr<res.size() && res[ptr]!=begin) {
@@ -257,7 +257,7 @@ token lexer::str_gen() {
 token lexer::single_opr() {
     u32 begin_line=line;
     u32 begin_column=column;
-    string str(1,res[ptr]);
+    std::string str(1,res[ptr]);
     ++column;
     tok type=get_type(str);
     if (type==tok::null) {
@@ -270,7 +270,7 @@ token lexer::single_opr() {
 token lexer::dots() {
     u32 begin_line=line;
     u32 begin_column=column;
-    string str=".";
+    std::string str=".";
     if (ptr+2<res.size() && res[ptr+1]=='.' && res[ptr+2]=='.') {
         str+="..";
     }
@@ -283,7 +283,7 @@ token lexer::calc_opr() {
     u32 begin_line=line;
     u32 begin_column=column;
     // get calculation operator
-    string str(1,res[ptr++]);
+    std::string str(1,res[ptr++]);
     if (ptr<res.size() && res[ptr]=='=') {
         str+=res[ptr++];
     }
@@ -291,7 +291,7 @@ token lexer::calc_opr() {
     return {{begin_line, begin_column, line, column, filename}, get_type(str), str};
 }
 
-const error& lexer::scan(const string& file) {
+const error& lexer::scan(const std::string& file) {
     line=1;
     column=0;
     ptr=0;
diff --git a/ast/nasal_new_lexer.h b/ast/nasal_new_lexer.h
index 0f4adfd..c4669c2 100644
--- a/ast/nasal_new_lexer.h
+++ b/ast/nasal_new_lexer.h
@@ -12,8 +12,8 @@
 #include <unordered_map>
 #include <sys/stat.h>
 
-#include "nasal.h"
-#include "nasal_err.h"
+#include "nasal_new_header.h"
+#include "nasal_new_err.h"
 
 #ifdef _MSC_VER
 #define S_ISREG(m) (((m)&0xF000)==0x8000)
@@ -81,9 +81,9 @@ enum class tok:u32 {
 };
 
 struct token {
-    span loc;    // location
-    tok type;    // token type
-    string str;  // content
+    span loc; // location
+    tok type; // token type
+    std::string str; // content
     token() = default;
     token(const token&) = default;
 };
@@ -93,11 +93,11 @@ private:
     u32    line;
     u32    column;
     usize  ptr;
-    string filename;
-    string res;
+    std::string filename;
+    std::string res;
     error& err;
     std::vector<token> toks;
-    const std::unordered_map<string,tok> typetbl {
+    const std::unordered_map<std::string, tok> typetbl {
         {"true"    ,tok::tktrue  },
         {"false"   ,tok::tkfalse },
         {"for"     ,tok::rfor    },
@@ -153,7 +153,7 @@ private:
         {">="      ,tok::geq     }
     };
 
-    tok get_type(const string&);
+    tok get_type(const std::string&);
     bool skip(char);
     bool is_id(char);
     bool is_hex(char);
@@ -166,8 +166,8 @@ private:
     void skip_note();
     void err_char();
 
-    void open(const string&);
-    string utf8_gen();
+    void open(const std::string&);
+    std::string utf8_gen();
     token id_gen();
     token num_gen();
     token str_gen();
@@ -175,7 +175,9 @@ private:
     token dots();
     token calc_opr();
 public:
-    lexer(error& e): line(1), column(0), ptr(0), filename(""), res(""), err(e) {}
-    const error& scan(const string&);
+    lexer(error& e):
+        line(1), column(0),
+        ptr(0), filename(""), res(""), err(e) {}
+    const error& scan(const std::string&);
     const std::vector<token>& result() const {return toks;}
 };
diff --git a/ast/new_main.cpp b/ast/nasal_new_main.cpp
similarity index 80%
rename from ast/new_main.cpp
rename to ast/nasal_new_main.cpp
index f1eb2b3..586243f 100644
--- a/ast/new_main.cpp
+++ b/ast/nasal_new_main.cpp
@@ -1,15 +1,9 @@
-#include "nasal.h"
-#include "nasal_err.h"
-#include "nasal_lexer.h"
-#include "nasal_ast.h"
-#include "nasal_parse.h"
-#include "nasal_import.h"
-#include "nasal_opt.h"
-#include "nasal_gc.h"
-#include "nasal_builtin.h"
-#include "nasal_codegen.h"
-#include "nasal_vm.h"
-#include "nasal_dbg.h"
+#include "nasal_new_header.h"
+#include "nasal_new_err.h"
+#include "nasal_new_lexer.h"
+#include "nasal_new_ast.h"
+#include "nasal_new_parse.h"
+#include "ast_visitor.h"
 
 #include <unordered_map>
 #include <thread>
@@ -73,8 +67,8 @@ void err() {
 }
 
 void execute(
-    const string& file,
-    const std::vector<string>& argv,
+    const std::string& file,
+    const std::vector<std::string>& argv,
     const u32 cmd
 ) {
     using clk=std::chrono::high_resolution_clock;
@@ -83,9 +77,9 @@ void execute(
     error   err;
     lexer   lex(err);
     parse   parse(err);
-    linker  ld(err);
-    codegen gen(err);
-    vm      ctx;
+    // linker  ld(err);
+    // codegen gen(err);
+    // vm      ctx;
 
     // lexer scans file to get tokens
     lex.scan(file).chkerr();
@@ -94,27 +88,27 @@ void execute(
     parse.compile(lex).chkerr();
 
     // linker gets parser's ast and load import files to this ast
-    ld.link(parse, file, cmd&VM_DETAIL).chkerr();
+    // ld.link(parse, file, cmd&VM_DETAIL).chkerr();
 
     // optimizer does simple optimization on ast
-    optimize(parse.tree());
-    if (cmd&VM_AST) {
-        parse.tree().dump();
-    }
+    // optimize(parse.tree());
+    // if (cmd&VM_AST) {
+    //     parse.tree().dump();
+    // }
 
     // code generator gets parser's ast and import file list to generate code
-    gen.compile(parse, ld).chkerr();
-    if (cmd&VM_CODE) {
-        gen.print();
-    }
+    // gen.compile(parse, ld).chkerr();
+    // if (cmd&VM_CODE) {
+    //     gen.print();
+    // }
 
     // run
     auto start=clk::now();
-    if (cmd&VM_DEBUG) {
-        dbg(err).run(gen, ld, argv);
-    } else if (cmd&VM_TIME || cmd&VM_EXEC) {
-        ctx.run(gen, ld, argv, cmd&VM_DETAIL);
-    }
+    // if (cmd&VM_DEBUG) {
+    //     dbg(err).run(gen, ld, argv);
+    // } else if (cmd&VM_TIME || cmd&VM_EXEC) {
+    //     ctx.run(gen, ld, argv, cmd&VM_DETAIL);
+    // }
 
     // get running time
     if (cmd&VM_TIME) {
@@ -132,7 +126,7 @@ i32 main(i32 argc, const char* argv[]) {
 
     // run directly or show help
     if (argc==2) {
-        string s(argv[1]);
+        std::string s(argv[1]);
         if (s=="-h" || s=="--help") {
             std::clog<<help;
         } else if (s[0]!='-') {
@@ -144,7 +138,7 @@ i32 main(i32 argc, const char* argv[]) {
     }
 
     // execute with arguments
-    const std::unordered_map<string,u32> cmdlst={
+    const std::unordered_map<std::string,u32> cmdlst = {
         {"--ast", VM_AST},
         {"-a", VM_AST},
         {"--code", VM_CODE},
@@ -159,8 +153,8 @@ i32 main(i32 argc, const char* argv[]) {
         {"-dbg", VM_DEBUG}
     };
     u32 cmd=0;
-    string filename="";
-    std::vector<string> vm_argv;
+    std::string filename="";
+    std::vector<std::string> vm_argv;
     for(i32 i=1; i<argc; ++i) {
         if (cmdlst.count(argv[i])) {
             cmd|=cmdlst.at(argv[i]);
diff --git a/ast/nasal_new_misc.cpp b/ast/nasal_new_misc.cpp
new file mode 100644
index 0000000..97ae1c7
--- /dev/null
+++ b/ast/nasal_new_misc.cpp
@@ -0,0 +1,230 @@
+#include "nasal_new_header.h"
+
+bool is_windows() {
+#if defined(_WIN32) || defined(_WIN64)
+    return true;
+#else
+    return false;
+#endif
+}
+
+bool is_linux() {
+#if defined __linux__
+    return true;
+#else
+    return false;
+#endif
+}
+
+bool is_macos() {
+#if defined __APPLE__
+    return true;
+#else
+    return false;
+#endif
+}
+
+bool is_x86() {
+#if defined(__i386__) || defined(_M_IX86)
+    return true;
+#else
+    return false;
+#endif
+}
+
+bool is_amd64() {
+#if defined(__amd64__) || defined(_M_X64)
+    return true;
+#else
+    return false;
+#endif
+}
+
+bool is_x86_64() {
+    return is_amd64();
+}
+
+bool is_arm() {
+#if defined(__arm__) || defined(_M_ARM)
+    return true;
+#else
+    return false;
+#endif
+}
+
+bool is_aarch64() {
+#if defined(__aarch64__) || defined(_M_ARM64)
+    return true;
+#else
+    return false;
+#endif
+}
+
+bool is_ia64() {
+#if defined(__ia64__)
+    return true;
+#else
+    return false;
+#endif
+}
+
+bool is_powerpc() {
+#if defined(__powerpc__)
+    return true;
+#else
+    return false;
+#endif
+}
+
+bool is_superh() {
+#if defined(__sh__)
+    return true;
+#else
+    return false;
+#endif
+}
+
+f64 hex2f(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 oct2f(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 dec2f(const char* str) {
+    f64 ret=0,negative=1,num_pow=0;
+    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++=='-'? -1:1);
+    }
+    if (!*str) {
+        return nan("");
+    }
+    num_pow=0;
+    while('0'<=*str && *str<='9') {
+        num_pow=num_pow*10+(*str++-'0');
+    }
+    if (*str) {
+        return nan("");
+    }
+    return ret*std::pow(10,negative*num_pow);
+}
+
+f64 str2num(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=hex2f(str+2);
+    } else if (str[0]=='0' && str[1]=='o') {
+        res=oct2f(str+2);
+    } else {
+        res=dec2f(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 u8 c=(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 chrhex(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 (is_windows() && i<=0) {
+            ret+="\\x"+chrhex(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;
+}
\ No newline at end of file
diff --git a/ast/nasal_new_parse.cpp b/ast/nasal_new_parse.cpp
index ffa7c13..71bf125 100644
--- a/ast/nasal_new_parse.cpp
+++ b/ast/nasal_new_parse.cpp
@@ -129,17 +129,10 @@ bool parse::check_func_end(expr* node) {
         type==expr_type::ast_hash) {
         return false;
     }
-    if (node.child().empty() || (
-        type!=expr_type::ast_def &&
-        type!=expr_type::ast_equal &&
-        type!=expr_type::ast_addeq &&
-        type!=expr_type::ast_subeq &&
-        type!=expr_type::ast_multeq &&
-        type!=expr_type::ast_diveq &&
-        type!=expr_type::ast_lnkeq)) {
-        return false;
-    } else {
-        return check_func_end(node.child().back());
+    if (type==expr_type::ast_def) {
+        return check_func_end(((definition_expr*)type)->get_value());
+    } else if (type==expr_type::ast_assign) {
+        return check_func_end(((assignment_expr*)type)->get_right());
     }
     return false;
 }
@@ -301,7 +294,6 @@ void parse::params(function* func_node) {
         auto param = new parameter(toks[ptr].loc);
         param->set_parameter_name(id());
         if (lookahead(tok::eq) || lookahead(tok::ellipsis)) {
-            ast special_arg(toks[ptr].loc, ast_null);
             if (lookahead(tok::eq)) {
                 match(tok::eq);
                 param->set_parameter_type(parameter::param_type::default_parameter);
@@ -417,16 +409,31 @@ expr* parse::calc() {
         node = tmp;
     } else if (tok::eq<=toks[ptr].type && toks[ptr].type<=tok::lnkeq) {
         // tok::eq~tok::lnkeq is 37 to 42,ast_equal~ast_lnkeq is 21~26
-        ast tmp(toks[ptr].loc, (u32)toks[ptr].type-(u32)tok::eq+ast_equal);
-        tmp.add(std::move(node));
+        auto tmp = new assignment_expr(toks[ptr].loc);
+        switch(toks[ptr].type) {
+            case tok::eq: tmp->set_type(assignment_expr::assign_type::equal); break;
+            case tok::addeq: tmp->set_type(assignment_expr::assign_type::add_equal); break;
+            case tok::subeq: tmp->set_type(assignment_expr::assign_type::sub_equal); break;
+            case tok::multeq: tmp->set_type(assignment_expr::assign_type::mult_equal); break;
+            case tok::diveq: tmp->set_type(assignment_expr::assign_type::div_equal); break;
+            case tok::lnkeq: tmp->set_type(assignment_expr::assign_type::concat_equal); break;
+            default: break;
+        }
+        tmp->set_left(node);
         match(toks[ptr].type);
-        tmp.add(calc());
+        tmp->set_right(calc());
         node = tmp;
     } else if (toks[ptr].type==tok::btandeq || toks[ptr].type==tok::btoreq || toks[ptr].type==tok::btxoreq) {
-        ast tmp(toks[ptr].loc, (u32)toks[ptr].type-(u32)tok::btandeq+ast_btandeq);
-        tmp.add(std::move(node));
+        auto tmp = new assignment_expr(toks[ptr].loc);
+        switch(toks[ptr].type) {
+            case tok::btandeq: tmp->set_type(assignment_expr::assign_type::bitwise_and_equal); break;
+            case tok::btoreq: tmp->set_type(assignment_expr::assign_type::bitwise_or_equal); break;
+            case tok::btxoreq: tmp->set_type(assignment_expr::assign_type::bitwise_xor_equal); break;
+            default: break;
+        }
+        tmp->set_left(node);
         match(toks[ptr].type);
-        tmp.add(calc());
+        tmp->set_right(calc());
         node = tmp;
     }
     update_location(node);
diff --git a/ast/nasal_new_parse.h b/ast/nasal_new_parse.h
index 9753bc5..72abdd1 100644
--- a/ast/nasal_new_parse.h
+++ b/ast/nasal_new_parse.h
@@ -2,11 +2,10 @@
 
 #include <unordered_map>
 
-#include "nasal.h"
+#include "nasal_new_header.h"
 #include "nasal_new_ast.h"
-#include "nasal_lexer.h"
-#include "nasal_ast.h"
-#include "nasal_err.h"
+#include "nasal_new_lexer.h"
+#include "nasal_new_err.h"
 
 class parse {
 
@@ -22,7 +21,7 @@ private:
     error& err;
 
 private:
-    const std::unordered_map<tok,string> tokname {
+    const std::unordered_map<tok, std::string> tokname {
         {tok::rfor    ,"for"     },
         {tok::forindex,"forindex"},
         {tok::foreach ,"foreach" },
diff --git a/makefile b/makefile
index 160192e..5dfa980 100644
--- a/makefile
+++ b/makefile
@@ -18,24 +18,12 @@ SRC=\
 
 STD=c++14
 
-nasal:$(SRC) nasal_new_lexer.o nasal_new_ast.o nasal_new_parse.o ast_visitor.o
+nasal:$(SRC)
 	$(CXX) -std=$(STD) -O3 main.cpp -o nasal -fno-exceptions -ldl -Wshadow -Wall
 
 nasal.exe:$(SRC)
 	$(CXX) -std=$(STD) -O3 main.cpp -o nasal.exe -fno-exceptions -Wshadow -Wall -static
 
-nasal_new_lexer.o: ast/nasal_new_lexer.h ast/nasal_new_lexer.cpp nasal.h
-	$(CXX) -std=$(STD) -c -O3 ast/nasal_new_lexer.cpp -fno-exceptions -fPIC -o nasal_new_lexer.o -I .
-
-nasal_new_ast.o: ast/nasal_new_ast.h ast/nasal_new_ast.cpp nasal.h
-	$(CXX) -std=$(STD) -c -O3 ast/nasal_new_ast.cpp -fno-exceptions -fPIC -o nasal_new_ast.o -I .
-
-nasal_new_parse.o: ast/nasal_new_parse.h ast/nasal_new_parse.cpp nasal.h ast/nasal_new_ast.h
-#	$(CXX) -std=$(STD) -c -O3 ast/nasal_new_parse.cpp -fno-exceptions -fPIC -o nasal_new_parse.o -I .
-
-ast_visitor.o: ast/nasal_new_ast.h ast/ast_visitor.h ast/ast_visitor.cpp
-	$(CXX) -std=$(STD) -c -O3 ast/ast_visitor.cpp -fno-exceptions -fPIC -o ast_visitor.o -I .
-
 stable-release:$(SRC)
 	$(CXX) -std=$(STD) -O2 main.cpp -o nasal -fno-exceptions -ldl -Wshadow -Wall
 
@@ -83,4 +71,43 @@ test:nasal
 	@ ./nasal -t -d test/turingmachine.nas
 	@ ./nasal -d test/wavecollapse.nas
 	@ ./nasal test/word_collector.nas test/md5compare.nas
-	@ ./nasal -t -d test/ycombinator.nas
\ No newline at end of file
+	@ ./nasal -t -d test/ycombinator.nas
+
+NASAL_NEW_AST=\
+	nasal_new_misc.o\
+	nasal_new_err.o\
+	nasal_new_lexer.o\
+	nasal_new_ast.o\
+	nasal_new_parse.o\
+	ast_visitor.o\
+	nasal_new_main.o
+
+# for test
+nasal_new: $(NASAL_NEW_AST)
+	$(CXX) $(NASAL_NEW_AST) -o nasal_new
+	@ echo "build done"
+
+nasal_new_main.o: ast/nasal_new_main.cpp
+	$(CXX) -std=$(STD) -c -O3 ast/nasal_new_main.cpp -fno-exceptions -fPIC -o nasal_new_main.o -I .
+
+nasal_new_misc.o: ast/nasal_new_header.h ast/nasal_new_misc.cpp
+	$(CXX) -std=$(STD) -c -O3 ast/nasal_new_misc.cpp -fno-exceptions -fPIC -o nasal_new_misc.o -I .
+
+nasal_new_err.o: ast/nasal_new_err.h ast/nasal_new_err.cpp
+	$(CXX) -std=$(STD) -c -O3 ast/nasal_new_err.cpp -fno-exceptions -fPIC -o nasal_new_err.o -I .
+
+nasal_new_lexer.o: ast/nasal_new_lexer.h ast/nasal_new_lexer.cpp
+	$(CXX) -std=$(STD) -c -O3 ast/nasal_new_lexer.cpp -fno-exceptions -fPIC -o nasal_new_lexer.o -I .
+
+nasal_new_ast.o: ast/nasal_new_ast.h ast/nasal_new_ast.cpp
+	$(CXX) -std=$(STD) -c -O3 ast/nasal_new_ast.cpp -fno-exceptions -fPIC -o nasal_new_ast.o -I .
+
+nasal_new_parse.o: ast/nasal_new_parse.h ast/nasal_new_parse.cpp ast/nasal_new_ast.h
+	$(CXX) -std=$(STD) -c -O3 ast/nasal_new_parse.cpp -fno-exceptions -fPIC -o nasal_new_parse.o -I .
+
+ast_visitor.o: ast/nasal_new_ast.h ast/ast_visitor.h ast/ast_visitor.cpp
+	$(CXX) -std=$(STD) -c -O3 ast/ast_visitor.cpp -fno-exceptions -fPIC -o ast_visitor.o -I .
+
+.PHONY: nasal_new_clean
+nasal_new_clean:
+	rm $(NASAL_NEW_AST)
\ No newline at end of file