euler1.hs

import IO

wanted :: (Integral a) => a -> Bool
wanted x
    | mod 3 x == 0 = True
    | mod 5 x == 0 = True
    | otherwise = False

problem1 :: (Integral a) => a -> a
problem1 x = sum $ filter wanted [1 .. x]

main = do
    let answer = show $ problem1 1000 in putStrLn answer

-- prints 9 :(