fizzbuzz.hs

import Data.List

nums = map (Just . show) [1..]
fizz = cycle [Nothing, Nothing, Just "Fizz"]
buzz = cycle [Nothing, Nothing, Nothing, Nothing, Just "Buzz"]

fb n f b = case (n, f, b) of
  (_, Just x, Just y) -> x ++ y
  (_, Just x, Nothing) -> x
  (_, Nothing, Just y) -> y
  (Just n, _, _) -> n

fizzBuzz = zipWith3 fb nums fizz buzz

main = mapM_ putStrLn $ take 100 fizzBuzz