Decided my next goal in life will be to gauge my learning Haskell progress by using it to find solutions to all of the Project Euler problems.
So far so good, I completed the first one with success.
The very compact and elegant Haskell one-liner solution is:
sum [ x | x <- [1..999], x `mod` 3 == 0 || x `mod` 5 == 0]
There's still a long way to go...