type alias

Author: 刘建秋

EN/type.md

@@ -39,6 +39,53 @@ type handle func (str string)
 
 ```
 
+###### Type aliases and type definitions (Distinction)
+
+Define built-in type definitions prior to Go 1.9:
+```
+type byte uint8
+type rune int32
+```
+
+After Go 1.9, it becomes:
+```
+type byte = uint8
+type rune = int32
+```
+This change is made in conjunction with the type alias.
+
+The definition of a type alias is written as:
+```
+type TypeAlias = Type
+```
+A Type alias specifies that a TypeAlias is an alias to a Type; essentially, a TypeAlias is the same Type as a Type.
+
+```
+package main
+import (
+"fmt"
+)
+// Define NewInt as int
+type NewInt int
+// Use an int as IntAlias
+type IntAlias = int
+func main() {
+// Declare A as type NewInt
+var a NewInt
+// View the type name of A
+fmt.Printf("a type: %T\n", a)
+Declare A2 as type IntAlias
+var a2 IntAlias
+// View the type name of A2
+fmt.Printf("a2 type: %T\n", a2)
+}
+
+// a type: main.NewInt
+// a2 type: int
+
+```
+
+
 ###### Type Switch
 ```
 func Demo (params ... interface (}) {

zh_CN/type.md

@@ -33,12 +33,54 @@ type Demo string
 
 ```
 
+
 ###### 类型定义
 ```
 type handle func(str string) 
 
 ```
 
+###### 类型别名和类型定义（区别）
+
+在 Go 1.9 版本之前定义内建类型的定义：
+type byte uint8
+type rune int32
+
+而在 Go 1.9 版本之后变为：
+type byte = uint8
+type rune = int32
+这个修改就是配合类型别名而进行的修改。
+
+定义类型别名的写法为：
+type TypeAlias = Type
+类型别名规定：TypeAlias 只是 Type 的别名，本质上 TypeAlias 与 Type 是同一个类型
+
+```
+package main
+import (
+    "fmt"
+)
+// 将NewInt定义为int类型
+type NewInt int
+// 将int取一个别名叫IntAlias
+type IntAlias = int
+func main() {
+    // 将a声明为NewInt类型
+    var a NewInt
+    // 查看a的类型名
+    fmt.Printf("a type: %T\n", a)
+    // 将a2声明为IntAlias类型
+    var a2 IntAlias
+    // 查看a2的类型名
+    fmt.Printf("a2 type: %T\n", a2)
+}
+
+// a type: main.NewInt
+// a2 type: int
+
+```
+
+
 ###### 类型开关
 ```
 func Demo(params ...interface{})  {