6 lines
218 B
Haskell
6 lines
218 B
Haskell
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permutations :: [a] -> [[a]]
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permutations [] = [[]]
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permutations xs = [ y:zs | (y,ys) <- select xs, zs <- permutations ys]
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where select [] = []
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select (x:xs) = (x,xs) : [ (y,x:ys) | (y,ys) <- select xs ]
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