Project Eular 32 by Haskell

gistfile1.hs

import Data.List

make_list :: [Int]
make_list = [x * y | x <- [1..5000],y <- [1..5000], ((sort ((show x) ++ (show y) ++ (show (x * y)))) == "123456789")]

duple_filter :: [Int] -> [Int] -> [Int]
duple_filter x y 
    | y == [] = x
    | otherwise = duple_filter ((head y) : x) (filter (/= (head y)) y)

main = putStrLn $ show $ sum $ duple_filter [0] $ make_list