Haskell Quiz/FizzBuzz/Solution Syzygies

Fizz comes before Buzz comes before an integer. Fizz and Buzz stick to each other, but hide integers.

The lists for Fizz and Buzz are infinite, but zipping together with a finite list of integers, the result is finite.

module Main where

main :: IO ()
main = mapM_ putStrLn $ zipWith3 join (loop 3 "Fizz") (loop 5 "Buzz") [1..100]
  where
    xor s t = if null s then t else s
    loop n s = cycle $ replicate (n-1) [] ++ [s]
    join s t n = xor (s ++ t) (show n)

If one has enabled all warnings as errors, then the integers need an explicit type, as shown below.

The hiding logic can also be implemented by filtering for the first non-null element of a list:

module Main where
  module Main where

  main :: IO ()
  main = sequence_ $ zipWith3 join (loop 3 "Fizz") (loop 5 "Buzz") [1..100 :: Int]
    where
      loop n s = cycle $ replicate (n-1) "" ++ [s]
      join s t n = putStrLn . head $ filter (not . null) [s ++ t, show n]