Far from the beauty of Knuth version implemented here by Mike but it was my first time to attempt to resolve such problem.

Anyway, my python version of a generator that returns successive permutations in order.

def permutations_of( seq ):
    yield seq
    seqlen = len(seq)
    while True:
        j = seqlen - 2
        while j >= 0 and seq[j] >= seq[j+1]:
            j -= 1

        if j < 0: break

        i= seqlen - 1
        while i > j and seq[i] < seq[j]:
            i -= 1

        seq[j],seq[i] = seq[i],seq[j]
        seq[j+1:] = seq[-1:j:-1]
        yield seq

import Data.List
import qualified Data.List.Key as K

perms :: (a -> a -> Bool) -> [a] -> [[a]]
perms cmp xs = map fst . K.sort (reverse . snd) . map unzip $
               permutations [(x, length $ filter (cmp x) xs) | x <- xs]