fizzbuzz in haskell?

Question

I'm trying to write 'fizzbuzz' in haskell using list comprehensions.

Why doesn't the following work, and how should it be?

[ if x `mod` 5 == 0 then "BUZZFIZZ"
  if x `mod` 3 == 0 then "BUZZ" 
  if x `mod` 4 == 0 then "FIZZ" | x <- [1..20], 
    x `mod` 3 == 0, 
    x `mod` 4 == 0, 
    x `mod` 5 == 0 ]

Answer 1

This isn't valid Haskell. The else branch is not optional in if ... then ... else. Rather than using if, this seems like a good opportunity to use a case statement.

case (x `rem` 3, x `rem` 5) of
  (0,0) -> "fizzbuzz"
  (0,_) -> "fizz"
  (_,0) -> "buzz"
  _     -> show x

This snippet will work for a traditional "fizzbuzz"; your code seems to be slightly different.