自定义类型基本练习

Basic-practice-of-FSharp/Basic-practice-of-FSharp.fsproj

@@ -14,5 +14,6 @@
     <Compile Include="FunctionSign.fs" />
     <Compile Include="CurryingFunction.fs" />
     <Compile Include="Loop.fs" />
+    <Compile Include="TypeCreating.fs" />
   </ItemGroup>
 </Project>

Basic-practice-of-FSharp/TypeCreating.fs

@@ -0,0 +1,87 @@
+module TypeCreating
+
+// 可区分联合
+type List =
+    | Cons of int * List
+    | Nil
+
+let list = Cons(1, Cons(2, Cons(3, Nil)))
+
+printfn "%A" list
+
+// 记录类型
+type UserInfo = {
+    Username: string
+    Password: string
+}
+
+let user = { Username = "小明"; Password = "123456" }
+
+printfn "%A" user
+
+// 结构类型
+// val表示字段是公有的
+// member 定义属性或者方法
+type UserInfoBtStruct = struct
+    val Username: string
+    val Password: string
+    new(username: string, password: string) = { Username = username; Password = password }
+
+    member this.Display() =
+        printfn $"用户名: {this.Username}  密码: {this.Password}"
+
+    member this.ToString() = this.Display()
+    end
+
+// 类
+// 类后面的括号表示主构造函数的参数
+// 如果let绑定的是函数,那他将编译为成员方法
+// 如果绑定的是未在任何函数或成员中使用的值,那他将编译为主构造函数中的本地变量
+// do绑定将会被编译为主构造函数
+// 不管使用了哪个构造函数,F#始终会执行let和do绑定
+type UserInfoByClass(username: string, password: string) =
+    let _username = username
+    let _password = password
+    do printfn "%A" "DoBinding"
+    member this.Username = _username
+    member this.Password = _password
+
+    member this.Display() =
+        printfn $"用户名: {this.Username}  密码: {this.Password}"
+
+    member this.ToString() = this.Display()
+    
+// 接口
+// 接口定义与类相似,但是并不实现任何成员,并且所有成员都是抽象的abstract
+// 接口默认访问修饰符为public
+type IUserInfo =
+    abstract member Display: unit -> unit
+
+// 继承接口
+// 使用as关键字可以自定义自我标识符,否则默认为this
+type UserInfoWith() =
+    interface IUserInfo with
+        member this.Display() = printfn "实现IUserInfo接口的Display方法"
+
+// 类的继承
+// type class-name(...)
+//     inherit base-class-name(...)
+//         other-member...
+
+// 虚方法与重写
+type BaseClass() =
+    let mutable counter = 0
+    // 虚方法声明
+    abstract member Method: int -> int
+    // 虚方法的默认实现
+    default this.Method(a) = counter <- counter + a; counter
+
+type SubClass() =
+    inherit BaseClass()
+    // 重写父类虚方法
+    override this.Method(a) = a + 1
+
+// 抽象类
+// 抽象类需要在类的前面加个[<AbstactClass>]特性
+// [<AbstactClass>]
+// type AbstactClass(...) = ...