Get all permutations of a list in Haskell

Question

I\'m trying to do this from scratch, without the use of a library outside the standard lib. Heres my code:

permutations :: [a] -> [[a]]
permutations (x:xs         


        

Answer 1

I think that this is shorter and more elegant variant for what others are suggesting:

permutate :: (Eq a) => [a] -> [[a]]
permutate [] = [[]]
permutate l = [a:x | a <- l, x <- (permutate $ filter (\x -> x /= a) l)]