小编ZCo*_*der的帖子

我对Haskell很陌生,我正试图扭转一个列表.同时我想反转该列表中的列表.例如:

Prelude> rev [[3,4,5],[7,5,2]]
[[2,5,7],[5,4,3]]

我知道以下代码反转了一个列表:

rev :: [[a]] -> [[a]]
rev [[]] = [[]]
rev [[x]] = [[x]]
rev xs = last xs : reverse (init xs)

我一直在苦苦挣扎,我已经对代码做了一些补充,但它仍然没有用,而且我被卡住了.

rev :: [[a]] -> [[a]]
rev [[]] = [[]]
rev [[x]] = [[x]]
rev xs = last xs : reverse (init xs)
rev [xs] = last [xs] : reverse (init [xs])

我很感激任何帮助.提前致谢.