如何修改Haskell列表的第i个元素? [英] how to modify the i-th element of a Haskell List?

问题描述

我正在寻找一种修改haskell List的第i个元素的方法.让我们说foobar是这样的功能，那么下面的工作.

I'm looking for a way to modify the i-th element of haskell List. let says foobar is such a function, then the following works.

let xs = ["a","b","c","d"]
foobar xs 2 "baba" -- xs = ["a","b","baba","d"]

感谢您的回复！

推荐答案

您可以使用splitAt做到这一点:

You can do it with splitAt:

Prelude> let xs = ["a","b","c","d"]
Prelude> (\(l,_:r)->l++"baba":r) $ splitAt 2 xs
["a","b","baba","d"]

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