fizzbuzz.hs

-- Saw a (joke?) stack exchange post about an extensible fizzbuzz implementation.
-- I was bored, so I thought I'd give my take on something similar in Haskell:

import qualified Data.Map.Strict as M
import Control.Monad (join)

fizzBuzz :: M.Map Int String -> Int -> String -> [String]
fizzBuzz dict n default_value = map (toWords . divisors) [1..n]
    where keys       = M.keys dict
          divisors n = filter (\x -> (n `mod` x) == 0) keys
          toWords    x | (length x == 0) = default_value
                       | otherwise       = join $ map (\k -> dict M.! k) x
                      
-- Examples! --

normal_fizzbuzz = M.fromList [(3,"Fizz"),(5,"Buzz")]
extended_fizzbuzz = M.fromList [(3,"Fizz"),(5,"Buzz"),(7,"Bar"),(11,"Baz"),(13,"Jazz")]

main = do
    mapM_ putStrLn $ fizzBuzz normal_fizzbuzz 25 "None"
    mapM_ putStrLn $ fizzBuzz extended_fizzbuzz 25 "None"
    
-- Much extend, very concise, wow. --