diff --git a/README.md b/README.md
index 2a00439b..e12c4b90 100644
--- a/README.md
+++ b/README.md
@@ -261,6 +261,30 @@ var (a,b,c)=[0,1,2]; # define multiple variables from a vector
var (a,b,c)=(0,1,2); # define multiple variables from a tuple
```
+Nasal has many special global symbols:
+
+```javascript
+globals; # hashmap including all global symbols and their values
+arg; # in global scope, arg is the command line arguments
+ # in local scope, arg is the dynamic arguments of this function call
+```
+
+For example:
+
+```javascript
+var a = 1;
+println(globals); # will print {a:1}
+```
+
+```javascript
+# nasal a b c
+println(arg); # will print ["a", "b", "c"]
+
+func() {
+ println(arg);
+}(1, 2, 3); # will print [1, 2, 3]
+```
+
Multi-assignment
@@ -767,6 +791,62 @@ If get this, Congratulations!
Ghost Type(for lib developers)
+
+It's quite easy to create a new ghost by yourself now.
+Look at the example below:
+
+```c++
+const auto ghost_for_test = "ghost_for_test";
+
+// declare destructor for ghost type
+void ghost_for_test_destructor(void* ptr) {
+ std::cout << "ghost_for_test::destructor (0x";
+ std::cout << std::hex << reinterpret_cast(ptr) << std::dec << ") {\n";
+ delete static_cast(ptr);
+ std::cout << " delete 0x" << std::hex;
+ std::cout << reinterpret_cast(ptr) << std::dec << ";\n";
+ std::cout << "}\n";
+}
+
+var create_new_ghost(var* args, usize size, gc* ngc) {
+ var res = ngc->alloc(vm_obj);
+ // create ghost type
+ res.obj().set(ghost_for_test, ghost_for_test_destructor, new u32);
+ return res;
+}
+
+var print_new_ghost(var* args, usize size, gc* ngc) {
+ var res = args[0];
+ // check ghost type by the type name
+ if (!res.objchk(ghost_for_test)) {
+ std::cout << "print_new_ghost: not ghost for test type.\n";
+ return nil;
+ }
+ std::cout << "print_new_ghost: " << res.obj() << " result = "
+ << *((u32*)res.obj().ptr) << "\n";
+ return nil;
+}
+```
+
+We use this function to create a new ghost type:
+
+`void nas_ghost::set(const std::string&, nasal::nas_ghost::destructor, void*);`
+
+`const std::string&` is the name of the ghost type.
+
+`nasal::nas_ghost::destructor` is the pointer of the destructor of the ghost type.
+
+`void*` is the pointer of the ghost type instance.
+
+And we use this function to check if value is the correct ghost type:
+
+`bool var::objchk(const std::string&);`
+
+The parameter is the name of the ghost type.
+
+多变量赋值
@@ -741,6 +765,61 @@ dylib.dlclose(dlhandle.lib);
自定义类型(开发者教程)
+
+创建一个自定义类型现在不是很困难。下面是使用示例：
+
+```c++
+const auto ghost_for_test = "ghost_for_test";
+
+// 声明自定义类型的析构函数
+void ghost_for_test_destructor(void* ptr) {
+ std::cout << "ghost_for_test::destructor (0x";
+ std::cout << std::hex << reinterpret_cast(ptr) << std::dec << ") {\n";
+ delete static_cast(ptr);
+ std::cout << " delete 0x" << std::hex;
+ std::cout << reinterpret_cast(ptr) << std::dec << ";\n";
+ std::cout << "}\n";
+}
+
+var create_new_ghost(var* args, usize size, gc* ngc) {
+ var res = ngc->alloc(vm_obj);
+ // 创建自定义类型
+ res.obj().set(ghost_for_test, ghost_for_test_destructor, new u32);
+ return res;
+}
+
+var print_new_ghost(var* args, usize size, gc* ngc) {
+ var res = args[0];
+ // 用自定义类型的名字来检查是否是正确的自定义类型
+ if (!res.objchk(ghost_for_test)) {
+ std::cout << "print_new_ghost: not ghost for test type.\n";
+ return nil;
+ }
+ std::cout << "print_new_ghost: " << res.obj() << " result = "
+ << *((u32*)res.obj().ptr) << "\n";
+ return nil;
+}
+```
+
+我们使用下面这个函数来创建一个自定义类型：
+
+`void nas_ghost::set(const std::string&, nasal::nas_ghost::destructor, void*);`
+
+`const std::string&` 是自定义类型的类型名。
+
+`nasal::nas_ghost::destructor` 是自定义类型的析构函数指针。
+
+`void*` 是指向自定义类型实例的指针。
+
+我们使用下面的这个函数检测是否是正确的自定义类型：
+
+`bool var::objchk(const std::string&);`
+
+参数是自定义类型的类型名。
+
+