-- import Text.Parsec
-- import Text.Regex.Posix

oddEx :: Integer -> Bool
oddEx n = case quotRem n 10 of
    (0,0) -> False
    (0,r) -> odd r
    (q,r) -> odd r && oddEx q

oddEx' :: Integer -> Bool
oddEx' = all (flip notElem "02468") . show

-- oddEx'' :: Integer -> Bool
-- oddEx'' = (== "") . (=~ "[02468]") . show

-- oddEx''' :: Integer -> Bool
-- oddEx''' = either (const False) (const True) . parse (many1 (noneOf "02468") >> eof) "" . show

main :: IO ()
main = do
    let xs = [0..1000]
        a = filter oddEx xs
    print $ a
    print $ all ((a ==) . flip filter xs) [oddEx' -- ,oddEx'' ,oddEx'''
                                          ]