功能定义 [英] Greaters function define

问题描述

我想定义一个更大的功能，该功能从列表中选择比之前更大的项目.

I would like to define a greaters function, which selects from a list items that are larger than the one before it.

例如:

greaters [1,3,2,4,3,4,5] == [3,4,4,5]
greaters [5,10,6,11,7,12] == [10,11,12]

我想出的定义是这样的:

The definition I came up with is this :

greaters :: Ord a => [a] -> [a]

到目前为止我尝试过的事情:

Things I tried so far:

greaters (x:xs) = group [ d | d <- xs, x < xs ]

有什么提示吗?

推荐答案

我将从这里开始:

greaters :: Ord a => [a] -> [a]
greaters [] = []
greaters (x:xs) = greatersImpl x xs
    where
        greatersImpl last [] = <fill this out>
        greatersImpl last (x:xs) = <fill this out>

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