[Haskell-cafe] Re: Generic permutations

[Cetin Sert]

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 <jed at 59a2.org> 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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