RosettaCodeData/Task/Roman-numerals-Encode/Haskell/roman-numerals-encode-2.hs

22 lines
501 B
Haskell

import Data.List (mapAccumL)
roman :: [(Int, String)] -> Int -> String
roman vks n =
concat . snd $
mapAccumL
(\a (m, s) ->
let (q, r) = quotRem a m
in (r, [1 .. q] >> s))
n
vks
romanFromInt :: Int -> String
romanFromInt =
roman $
zip
[1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1]
["M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I"]
main :: IO ()
main = (putStrLn . unlines) (romanFromInt <$> [1666, 1990, 2008, 2016, 2018])