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在Ramda中相当于Haskell的const函数

[英]Equivalent of Haskell's const function in Ramda

原文 2017-01-29 19:25:29 6 2 javascript/ ramda.js

Does Ramda have a function that works the same as Haskell's const function , ie takes two parameters and returns the first one? Ramda是否具有与Haskell的const函数相同的功能，即采用两个参数并返回第一个参数？

I'm aware that it could be easily implemented as R.curry((a, b) => a) , but if Ramda already has such a function, I think I should use it instead of my own implementation. 我知道可以很容易地将其实现为R.curry((a, b) => a) ，但是如果Ramda已经具有这样的功能，我想我应该使用它而不是自己的实现。

2 个解决方案

This function is named always in Ramda. 该功能在Ramda中always被命名。

Returns a function that always returns the given value. 返回始终返回给定值的函数。 Note that for non-primitives the value returned is a reference to the original value. 请注意，对于非基本元素，返回的值是对原始值的引用。

This function is known as const , constant , or K (for K combinator) in other languages and libraries. 在其他语言和库中，此函数称为const ， constant或K （对于K组合器）。

Ramda doesn't provide a function of type a -> b -> a . Ramda不提供类型a -> b -> a a- a -> b -> a的函数。 As Gothdo's answer states, Ramda does provide R.always :: a -> (() -> a) which is similar. 正如Gothdo的回答所指出的那样， R.always :: a -> (() -> a)确实提供了R.always :: a -> (() -> a) 。

Adding an a -> b -> a function to Ramda was proposed in ramda/ramda#1680 , but that thread has not been active for some time. 在ramda / ramda＃1680中建议向Ramda添加a- a -> b -> a函数，但是该线程已经有一段时间没有被激活了。

Sanctuary does provide a true const function, SK :: a -> b -> a . Sanctuary确实提供了真正的const函数，即SK :: a -> b -> a 。