Haskell组合（。）与F＃的管道转发运算符（|>） [英] Haskell composition (.) vs F#'s pipe forward operator (|>)

问题描述

在F＃中，使用管道转发操作符 |> 很常见。然而，在Haskell中，我只见过函数组合，（。），正在使用。我了解他们的相关，但是有没有一个语言的原因，没有使用管道转发在Haskell中，或者是别的什么？

我正在一点点我认为 |> 是一个重要的操作符在F＃的文化中，也许与Haskell的。类似。 F＃有一个函数组合操作符<< ，但我认为F＃社区倾向于使用

语言差异：我不喜欢这种风格，我们对两种语言都有足够的了解来进行比较，但是可能的普遍化让绑定的规则有很大的不同，以至于影响这一点。例如，我知道在F＃中有时会写

  let f = exp 
  

不会编译，您需要显式的eta转换：

 令fx =（exp）x //或x |> exp 
  

使其编译。这也使人们远离无点/构图风格，并转向流水线风格。此外，F＃类型推断有时需要流水线操作，因此左侧会出现已知类型（请参阅）。

（个人而言，我觉得无点式风格是不可读的，但我想每个新的/不同的东西似乎都是不可读的，除非您习惯于）

我认为两种语言在任何一种语言中都具有潜在的可行性，历史/文化/意外可能会解释为什么每个社区都有不同的吸引力。 >

In F#, use of the the pipe-forward operator, |>, is pretty common. However, in Haskell I've only ever seen function composition, (.), being used. I understand that they are related, but is there a language reason that pipe-forward isn't used in Haskell or is it something else?

解决方案

I am being a little speculative...

Culture: I think |> is an important operator in the F# "culture", and perhaps similarly with . for Haskell. F# has a function composition operator << but I think the F# community tends to use points-free style less than the Haskell community.

Language differences: I don't know enough about both languages to compare, but perhaps the rules for generalizing let-bindings are sufficiently different as to affect this. For example, I know in F# sometimes writing

let f = exp

will not compile, and you need explicit eta-conversion:

let f x = (exp) x   // or x |> exp

to make it compile. This also steers people away from points-free/compositional style, and towards the pipelining style. Also, F# type inference sometimes demands pipelining, so that a known type appears on the left (see here).

(Personally, I find points-free style unreadable, but I suppose every new/different thing seems unreadable until you become accustomed to it.)

I think both are potentially viable in either language, and history/culture/accident may define why each community settled at a different "attractor".

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