Project Euler Problem 024

import Data.List

perms :: Eq a => [a] -> [[a]]
perms []=[[]]
perms l = [x:xs|x<-l,xs<-perms(l\\[x])]
-- 3sec
ans1 :: [Char]
ans1 = perms "0123456789" !! 999999 -- "2783915460" ok。3sec in interpreter
-- 6sec
ans2 :: [Char]
ans2= (sort $ permutations "0123456789")!!999999
-- 2783915460
main :: IO ()
main = print ans1