Re: [Haskell-cafe] Re: Generic permutations

Thanks Jed, replicateM is almost as performant as pms on my pc (+ 2~ seconds). That's a killer suggestion... thank you very much ^_^ --Cetin Sert On 27/01/2008, Jed Brown 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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