Haskell標准庫函數進行轉換

Question

Haskell具有Data.List.permutations

permutations "abc" == ["abc","bac","cba","bca","cab","acb"]

是否有用於轉換的標准庫函數，或者您需要自己滾動？

transformations "ab" == ["aa","ab","ba","bb"]

Ruby的方式是：

 x.repeated_permutation(x.length)

Answer 1

您正在尋找replicateM中Control.Monad模塊：

replicateM 2 "ab"
-- ["aa","ab","ba","bb"]

現場演示

AFAIK它們是與字母['a', 'b']重復的排列。