「FizzBuzzクイズ」クイズ - Haskell版？ ref: http://qiita.com/nobsun/items/285f208a17285953f2ab

FizzBuzz.hs

{-# LANGUAGE TupleSections #-}
module FizzBuzz where

import Data.Bool

{- |
>>> gFB (fizz.buzz) 1
"1"
>>> gFB (fizz.buzz) 3
"Fizz"
>>> gFB (fizz.buzz) 5
"Buzz"
>>> gFB (fizz.buzz) 15
"FizzBuzz"
>>> gFB (buzz.fizz) 15
"BuzzFizz"
>>> gFB (fizz.buzz.pezz) 7
"Pezz"
>>> gFB (fizz.buzz.pezz) 21
"FizzPezz"
>>> gFB (fizz.buzz.pezz) 35
"BuzzPezz"
>>> gFB (fizz.buzz.pezz) 105
"FizzBuzzPezz"
>>> gFB (fizz.pezz.buzz) 105
"FizzPezzBuzz"
>>> gFB (pezz.buzz.fizz) 105
"PezzBuzzFizz"
>>> gFB (fizz.buzz.pezz) 1
"1"
>>> gFB (fizz.buzz.pezz) 3
"Fizz"iz
>>> gFB (fizz.buzz.pezz) 5
"Buzz"
>>> gFB (fizz.buzz.pezz) 15
"FizzBuzz"
>>> gFB (buzz.fizz.pezz) 15
"BuzzFizz"
>>> gFB (fizz.buzz.pezz) 104
"104"
-}
gFB :: ((Int, String) -> (Int, String)) -> Int -> String
gFB f = fin . f . (,"")

fin :: (Int, String) -> String
fin (n, s) = bool s (show n) (null s)

unit :: (Int, String) -> (Int, String) -> (Int, String)
unit (m, s) (n, t) = bool (n, t) (n, s ++ t) (n `mod` m == 0)

fizz :: (Int, String) -> (Int, String)
fizz = unit (3, "Fizz")

buzz :: (Int, String) -> (Int, String)
buzz = unit (5, "Buzz")

pezz :: (Int, String) -> (Int, String)
pezz = unit (7, "Pezz")

FizzBuzz2.hs

module FizzBuzz2 where

import Data.Bool

type FizzBuzz a = Int -> a

(|.|) :: FizzBuzz (b -> c) -> FizzBuzz (a -> b) -> FizzBuzz (a -> c)
f |.| g = (.) <$> f <*> g

unit :: Int -> String -> FizzBuzz ShowS
unit m s n = bool id (s++) (0 == mod n m)

fizz :: FizzBuzz ShowS
fizz = unit 3 "Fizz"

buzz :: FizzBuzz ShowS
buzz = unit 5 "Buzz"

pezz :: FizzBuzz ShowS
pezz = unit 7 "Pezz"

gFB :: FizzBuzz ShowS -> Int -> String
gFB f n = bool str (show n) (null str)
  where
    str = f n ""

{- ^
>>> gFB (fizz|.|buzz) 1
"1"
>>> gFB (fizz|.|buzz) 3
"Fizz"
>>> gFB (fizz|.|buzz) 5
"Buzz"
>>> gFB (fizz|.|buzz) 15
"FizzBuzz"
>>> gFB (buzz|.|fizz) 15
"BuzzFizz"
>>> gFB (fizz|.|buzz|.|pezz) 7
"Pezz"
>>> gFB (fizz|.|buzz|.|pezz) 21
"FizzPezz"
>>> gFB (fizz|.|buzz|.|pezz) 35
"BuzzPezz"
>>> gFB (fizz|.|buzz|.|pezz) 105
"FizzBuzzPezz"
>>> gFB (fizz|.|pezz|.|buzz) 105
"FizzPezzBuzz"
>>> gFB (pezz|.|buzz|.|fizz) 105
"PezzBuzzFizz"
>>> gFB (fizz|.|buzz|.|pezz) 1
"1"
>>> gFB (fizz|.|buzz|.|pezz) 3
"Fizz"
>>> gFB (fizz|.|buzz|.|pezz) 5
"Buzz"
>>> gFB (fizz|.|buzz|.|pezz) 15
"FizzBuzz"
>>> gFB (buzz|.|fizz|.|pezz) 15
"BuzzFizz"
>>> gFB (fizz|.|buzz|.|pezz) 104
"104"
-}