使用点表示法在 Scala 中链接函数 [英] Chaining function in Scala using dot notation

问题描述

到目前为止，我所知道的在 Scala 中将函数链接在一起的唯一本机方法是使用 andThen/compose.它完成了工作，但看起来仍然很笨重.例如，如果我有 3 个函数应用于一个值( f1(f2(f3(value))) )，我必须做这样的事情:

So far, the only native method of chaining functions together in Scala I know of is using andThen/compose. It gets the job done but still looks very clunky. For example, if I have 3 functions to apply to a value ( f1(f2(f3(value))) ), I have to do something like that:

(f1 _ andThen f2 andThen f3)(value)

当链更长并且函数需要超过 1 个参数时，问题会变得更糟.F# 使用|>"运算符非常优雅地解决了这个难题，但这种方法在 Scala 中效果不佳，因为该语言在很大程度上依赖于点表示法，而柯里化是可选的.

Problems get even worse when the chain is longer and the functions require more than 1 parameter. F# solves this conundrum very elegantly with the '|>' operator, but that approach doesn't work well in Scala, since the language relies a lot on dot notation and currying is optional.

所以问题是，是否可以在 Scala 中做这样的事情:

So the question is, is it possible to do something like this in Scala:

def addNumber(i: Int, s: String) = s + i
def doubleString(s: String) = (s + s, (s + s).length)
def trimString(i: (String, Int)) = i._1.substring(0, i._2-1)

addNumber(1,"Hello").doubleString.trimString

换句话说，我们可以使用点符号链接函数，前提是它们具有不同的返回类型/参数.

In other words can we chain functions using dot-notation, provided that they have different return types/arguments.

推荐答案

从 Scala 2.13 开始，您可以使用 pipe 链接操作员:

Starting Scala 2.13 you can use the pipe chaining operator:

import scala.util.chaining._

// def addNumber(i: Int, s: String) = s + i
// def doubleString(s: String) = (s + s, (s + s).length)
// def trimString(i: (String, Int)) = i._1.substring(0, i._2-1)
"Hello".pipe(addNumber(1, _)).pipe(doubleString).pipe(trimString)
// "Hello1Hello"

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