Haskell Quiz/FizzBuzz/Solution Heisenbug

 {-# LANGUAGE LambdaCase #-}

 main = mapM_ (putStrLn . fizzbuzz) [1 .. 100]
   where fizzbuzz n = (\case "" -> show n; fb -> fb)
                        (concat $ ["fizz" | n `rem` 3 == 0] ++ ["buzz" | n `rem` 5 == 0])