RosettaCodeData/Task/Run-length-encoding/Haskell/run-length-encoding.hs

25 lines
752 B
Haskell

import Data.List (group)
-- Datatypes
type Encoded = [(Int, Char)] -- An encoded String with form [(times, char), ...]
type Decoded = String
-- Takes a decoded string and returns an encoded list of tuples
rlencode :: Decoded -> Encoded
rlencode = map (\g -> (length g, head g)) . group
-- Takes an encoded list of tuples and returns the associated decoded String
rldecode :: Encoded -> Decoded
rldecode = concatMap decodeTuple
where decodeTuple (n,c) = replicate n c
main :: IO ()
main = do
-- Get input
putStr "String to encode: "
input <- getLine
-- Output encoded and decoded versions of input
let encoded = rlencode input
decoded = rldecode encoded
putStrLn $ "Encoded: " ++ show encoded ++ "\nDecoded: " ++ show decoded