FizzBuzz solution in Haskell

FizzBuzz

#! /usr/bin/env runhaskell

import Control.Monad (when, unless)

main :: IO ()
main = mapM_ fb [1..100]

fb :: Int -> IO ()
fb n = do
  let divBy3 = n `mod` 3 == 0
      divBy5 = n `mod` 5 == 0
  when divBy3 $ putStr "Fizz"
  when divBy5 $ putStr "Buzz"
  unless (divBy3 || divBy5) $ putStr . show $ n
  putChar '\n'