Question

我做错了什么？例如，这应该返回10：

{ val (get, set) = getAndSet (5); set (10); get () }

val getAndSet : Int => (() => Int, Int => Unit) = {
var s : Int = 0
val get : () => Int = () => {
  val z = s;
  s = s + 1;
  z
}
val set : Int => Unit = (x:Int) => {
  s = x
}
x => (get, set)
}

Answer 1

一些错误：

n不存在，您可能是s。
最后一行应为x => (get, set)，但您没有以任何方式使用x。

以下是您的代码中修改最少的版本

val getAndSet: Int => (() => Int, Int => Unit) = {
  var s: Int = 0
  val get : () => Int = () => {
    val z = s;
    s = s + 1;
    z
  }
  val set : Int => Unit = (x:Int) => {
    s = x
  }
  x => (get, set)
}

由于您未使用x，您可以选择

val getAndSet: Int => (() => Int, Int => Unit) = _ => {
  var s: Int = 0
  val get : () => Int = () => {
    val z = s;
    s = s + 1;
    z
  }
  val set : Int => Unit = (x:Int) => {
    s = x
  }
  (get, set)
}

Scala无状态函数

1 个答案: