在Elixir中引用管道值 [英] Referencing piped value in Elixir

问题描述

我想计算一个字符串中出现单词的次数。实现是有问题的，但是让我们用它来演示我的问题：

I want to count the number of word-occurrences in a string. The implementation is questionable, but lets use it to demonstrate my problem:

  def count(sentence) do
    words = String.split(sentence)
    occurrences = Enum.map(words, fn w -> {w, Enum.count(words, &(&1 == w))} end)
    Map.new(occurrences)
  end

我希望获得与上述相同的结果，但使用管道代替中间结果变量：

I would like to achieve the same result as above, but using pipes instead of intermediate result variables:

def count(sentence) do
    sentence
    |> String.split
    |> Enum.map(fn w -> {w, Enum.count(???)} end)
    |> Map.new
  end

是否可以引用枚举中的值。计数功能？还是我必须使用中间变量？

Is it possible to reference the piped in value in the Enum.count function? Or do i have to use an intermediate variable?

推荐答案

您可以在管道中放置一个匿名函数：

You can put an anonymous function in the pipeline:

def count(sentence) do
  sentence
  |> String.split
  |> (fn words -> Enum.map(words, fn w -> {w, Enum.count(words, &(&1 == w))} end) end).()
  |> Map.new
end

iex(1)> count("foo bar baz foo")
%{"bar" => 1, "baz" => 1, "foo" => 2}

这篇关于在Elixir中引用管道值的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！