haskell从列表列表中删除所有出现的给定值

Question

我想从列表列表中删除所有出现的给定值。例如， 输入：

'a' ["abc", "bc", "aa"] 

输出：

 ["bc", "bc", ""]

到目前为止：

remove :: Eq a => a -> [[a ]] -> [[a ]]
remove y xs = filter(\x -> x/= y) xs

我收到了错误，请提前谢谢。

Answer 1

您需要映射外部列表。

remove y xs = map (filter(\x -> x/= y)) xs

这里你实际上并不需要lambda，更好：

remove y xs = map (filter(/=y)) xs