Eitherの練習。リスト脳。

fizzbuzz.hs

type FizzBuzz = Either Int String
hit :: String -> FizzBuzz -> FizzBuzz
hit s (Left _) = Right s
hit s (Right s') = Right $ s ++ s'

fizz :: [ FizzBuzz -> FizzBuzz ]
fizz = cycle [ id, id, hit "fizz" ]
buzz :: [ FizzBuzz -> FizzBuzz ]
buzz = cycle [ id, id, id, id, hit "buzz" ]
fizzbuzz :: [ FizzBuzz -> FizzBuzz ]
fizzbuzz = zipWith (.) fizz buzz

emit :: FizzBuzz -> String
emit (Left n) = show n
emit (Right s) = s 

fizzbuzzlist :: [String]
fizzbuzzlist = map emit $ zipWith ($) fizzbuzz $ map Left [1..]

main :: IO ()
main = mapM_ putStrLn $ take 100 fizzbuzzlist