[Haskell-cafe] Re: Generic permutations

[Jed Brown]

On 26 Jan 2008, ryani.spam at gmail.com wrote:

> The problem you solved can be solved much more elegantly:
>
> pms : [a] -> Int -> [[a]]
> pms xs n = foldM combine [] (replicate n xs) where
> combine rest as = liftM (:rest) as
>
> or, for the unreadable version:
> pms xs n = foldM (map . flip (:)) [] $ replicate n xs

or, if you don't mind getting the elements in a different order:

  replicateM 3 [True,False]

Jed
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