Euler Project: Problem 1

If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23.
Find the sum of all the multiples of 3 or 5 below 1000.

Prelude> :m Data.List
Prelude Data.List> sum ([x| x <- [1..999], x `mod` 3 == 0] `union` [y| y <- [1..999], y `mod` 5 == 0])
233168