如何创建具有多个隐式参数的 Scala 匿名函数 [英] How do you create scala anonymous function with multiple implicit parameters

问题描述

我有名为run1"和run2"的 Scala 函数，它们接受 3 个参数.当我应用它们时，我想提供一个带有隐式参数的匿名函数.在下面的示例代码中，这两种情况都不起作用.我想知道

1. 这可能吗?
2. 如果可能，语法是什么?

<预><代码>对象主扩展应用程序{type fType = (Object, String, Long) => Objectdef run1( f: fType ) {f(新对象，第二个参数"，3)}run1 { 隐式 (p1, p2, p3) =>//失败打印(p1)打印(p2)打印(p3)新对象()}def run2( f: fType ) {val fC = f.curredfC(new Object)("第二个参数")(3)}run2 { 隐式 p1 => 隐式 p2 => 隐式 p3 =>//失败打印(p1)打印(p2)打印(p3)新对象()}}

解决方案

你在 run2 中柯里化了函数，所以 run2 仍然需要一个非柯里化的函数.请参阅下面的代码以了解有效的版本:

object Main 扩展 App {type fType = (Object, String, Long) =>目的类型 fType2 = 对象 =>字符串 =>长 =>对象//柯里化def run1( f: fType ) {f(新对象，第二个参数"，3)}//不起作用，语言规范不允许run1 { 隐式 (p1, p2, p3) =>打印(p1)打印(p2)打印(p3)新对象()}def run2( f: fType2 ) {f(new Object)("第二个参数")(3)}run2 { 隐式 p1 =>隐式 p2 =>隐式 p3 =>打印(p1)打印(p2)打印(p3)新对象()}}

I have scala functions called "run1" and "run2" which accept 3 parameters. When I apply them I want to provide an anonymous function with implicit parameters. It doesn't work in both cases in example codes below. I want to know if

1. Is that even possible?
2. If it is possible, what's the syntax?

       object Main extends App {
          type fType = (Object, String, Long) => Object

          def run1( f: fType ) {
            f( new Object, "Second Param", 3)
          }

          run1 { implicit (p1, p2, p3) => // fails
            println(p1)
            println(p2)
            println(p3)
            new Object()
          }

          def run2( f: fType ) {
            val fC = f.curried
            fC(new Object)("Second Param")(3)
          }

          run2 { implicit p1 => implicit p2 => implicit p3 => // fails
            println(p1)
            println(p2)
            println(p3)
            new Object()
          }
        }

解决方案

You're currying the function inside run2 so run2 still needs a non-curried function. See the code below for a version that works:

object Main extends App {
  type fType = (Object, String, Long) => Object
  type fType2 = Object => String => Long => Object //curried

  def run1( f: fType ) {
    f( new Object, "Second Param", 3)
  }

  // Won't work, language spec doesn't allow it
  run1 { implicit (p1, p2, p3) => 
    println(p1)
    println(p2)
    println(p3)
    new Object()
  }

  def run2( f: fType2 ) {
    f(new Object)("Second Param")(3)
  }

  run2 { implicit p1 => implicit p2 => implicit p3 =>
    println(p1)
    println(p2)
    println(p3)
    new Object()
  }
}

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