方便的F＃代码段 [英] Handy F# snippets

问题描述

已经有两个 有关F＃/功能代码段的问题。

但是我我在这里寻找的是有用片段，可重用的小辅助功能。或是您永远不会记得的晦涩但漂亮的模式。

However what I'm looking for here are useful snippets, little 'helper' functions that are reusable. Or obscure but nifty patterns that you can never quite remember.

类似的东西：

open System.IO

let rec visitor dir filter= 
    seq { yield! Directory.GetFiles(dir, filter)
          for subdir in Directory.GetDirectories(dir) do 
              yield! visitor subdir filter} 

我想将其作为一种方便的参考页。因此，没有正确的答案，但希望有很多好的答案。

I'd like to make this a kind of handy reference page. As such there will be no right answer, but hopefully lots of good ones.

编辑 Tomas Petricek创建了一个专门针对F＃代码段的网站< a href = http://fssnip.net/ rel = nofollow noreferrer> http://fssnip.net/ 。

EDIT Tomas Petricek has created a site specifically for F# snippets http://fssnip.net/.

推荐答案

中缀运算符

我从 http://sandersn.com/blog//index.php/2009/10/22/infix -function-trick-for-f 转到该页面以获取更多详细信息。

I got this from http://sandersn.com/blog//index.php/2009/10/22/infix-function-trick-for-f go to that page for more details.

如果您知道Haskell，您可能会发现自己在F＃中缺少中缀糖：

If you know Haskell, you might find yourself missing infix sugar in F#:

// standard Haskell call has function first, then args just like F#. So obviously
// here there is a function that takes two strings: string -> string -> string 
startsWith "kevin" "k"

//Haskell infix operator via backQuotes. Sometimes makes a function read better.
"kevin" `startsWith` "K" 

而F＃没有'infix'运算符，几乎可以通过管道和'backpipeline'（谁知道这样的事情？）来完成相同的事情

While F# doesn't have a true 'infix' operator, the same thing can be accomplished almost as elegantly via a pipeline and a 'backpipeline' (who knew of such a thing??)

// F# 'infix' trick via pipelines
"kevin" |> startsWith <| "K"

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