list - 如何将列表列表与列表列表结合起来

Question

我有列表列表，需要将其与另一个列表列表合并。输入示例: 答:[[1,2],[3,4],[5,6],[7,8]] B: [[1,2],[3,4],[5,6],[7,8]]

输出示例: [[1,2,1,2],[1,2,3,4],..,[7,8,5,6],[7,8,7,8]]

2 个列表的列表，其中都有 4 个列表，这将返回一个大小为 4*4 = 16 的列表列表

我尝试过递归地组合列表，但我知道即使通过也行不通。

  mergeAll [[]] [[]] = [[]]
  mergeAll [[]] b = b
  mergeAll a [[]] = a
  mergeAll xs ys = mergeAll (merge xs ys) (drop 1 ys) 

  merge :: [[a]] -> [[a]] -> [[a]]
  merge [[]] [[]] = [[]]
  merge xs [[]] = xs
  merge [[]] ys = ys
  merge (x:xs) (y:ys)  = ((x++y):xs)

Answer 1

您可以使用列表理解:

[ xs ++ ys | xs <- listOfLists1, ys <- listOfLists2 ]