haskell - haskell 在列表推导中迭代

Question

我想在 Haskell 中做这个

对于MyString = "ab"，n = 4结果应该是 >

["aaaa","aaab","aaba","aabb","abaa","abab","abba","abbb","baaa","baab","baba","babb","bbaa","bbab","bbba","bbbb"]

score 7 · Accepted Answer

7

replicateM 4 "ab"

给出你所要求的。您可以从Control.Monad.

于 2013-10-27T18:32:14.090 回答

score 1 · Accepted Answer

如果您想自己编写，可以执行以下操作。

seq i xs | i > 0 = [x:ys | x <- xs, ys <- seq (i-1) xs]
         | otherwise = [[]]

2 回答 2