Re: [Haskell-cafe] Permutations

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Nov 30, 2008, at 10:17 AM, Luke Palmer wrote:

On Sun, Nov 30, 2008 at 9:06 AM, Jake Mcarthur wrote:

...

Seems a bit easy, I think.

Data.List.permutations . nub

That is not what he meant. Given:

[1,1,2,2]

The results should be:

[1,1,2,2] [1,2,2,1] [2,2,1,1] [1,2,1,2] [2,1,2,1] [2,1,1,2]

Heh, after a couple more seconds of thought, reversing the two composed functions fixes it: nub . permutations Of course, neither my previous nonsolution nor this solution are efficient for long lists, but I think it serves as a decent reference implementation at least. - - Jake -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.8 (Darwin) iEYEARECAAYFAkkyv2wACgkQye5hVyvIUKmjBwCfSYebuPUNSqENppJG9sVxy+wB ehYAoJjEY9M2o8ZqgN7R5pQ9x2PF54Ew =ipuT -----END PGP SIGNATURE-----