元组和函数组合 [英] Tuple and function composition

问题描述

有没有更好的方法来表达 ((a, b) -> a < b) 与函数组合?我觉得我错过了一些东西，而尝试 curry 只会让我更加困惑.

Is there a better way to express ((a, b) -> a < b) with function composition? I feel like I'm missing something and experimenting with curry only confused me more.

推荐答案

curry 在这里用错了；它将对元组进行操作的函数转换为柯里化函数.您想要相反，即 uncurry:

curry is the wrong thing to use here; it turns a function operating on tuples into a curried function. You want the opposite, which is uncurry:

uncurry :: (a -> b -> c) -> (a, b) -> c

在这种情况下，它是 uncurry (<).

In this case, it's uncurry (<).

(用于在元组上编写函数的组合器的另一个有用来源是 Control.Arrow; 因为 (->) 是 Arrow 的一个实例，所以可以阅读 <代码>abc 为 b -> c.)

(Another useful source for combinators useful in writing functions on tuples is Control.Arrow; since (->) is an instance of Arrow, you can read a b c as b -> c.)

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