Scala推理_

我是scala（fxnl编程）的新手，不过我在下面的一些地方把它放在上下文中

list.map(_ * 1) 

我不能完全理解这句话

val story = (catch _) andThen (eat _)

虽然我可以从电话中推断

story(new Cat, new Bird)

下划线用作参数位置的占位符，我想了解它背后的概念。

语句

不正确-因为catch是关键字

但这是正确的：

scala> def caught(x:Int) = x + 8
caught: (x: Int)Int

scala> def eat(x:Int) = x + 3
eat: (x: Int)Int

scala> val story = (caught _) andThen (eat _) // story is function.
story: Int => Int = <function1>

scala> story(90) // You put 90 - parameter for caught (first _). It returns 90 + 8 and put it to eat (second _). eat function return 98 + 3
res0: Int = 101

scala>def捕获（x:Int）=x+8
捕获：（x:Int）Int
scala>defeat（x:Int）=x+3
吃：（x:Int）Int
scala>val story=（捕获）和（吃）//story是函数。
故事：Int=>Int=
scala>story（90）//您将90-参数放在catch（first)上。它返回90+8并将其放入食物中（秒）。eat函数返回98+3
res0:Int=101

语句

不正确-因为catch是关键字

但这是正确的：

scala> def caught(x:Int) = x + 8
caught: (x: Int)Int

scala> def eat(x:Int) = x + 3
eat: (x: Int)Int

scala> val story = (caught _) andThen (eat _) // story is function.
story: Int => Int = <function1>

scala> story(90) // You put 90 - parameter for caught (first _). It returns 90 + 8 and put it to eat (second _). eat function return 98 + 3
res0: Int = 101

scala>def捕获（x:Int）=x+8
捕获：（x:Int）Int
scala>defeat（x:Int）=x+3
吃：（x:Int）Int
scala>val story=（捕获）和（吃）//story是函数。
故事：Int=>Int=
scala>story（90）//您将90-参数放在catch（first)上。它返回90+8并将其放入食物中（秒）。eat函数返回98+3
res0:Int=101

浏览此答案，了解下划线的用法：感谢您在搜索时发现此为，浏览此答案，了解下划线的用法：感谢您在搜索时发现此为