Daily Programmer #212 Easy

robber.hs

-- Implementation of Reddit /r/DailyProgrammer challenge #212 [Easy]
-- Rövarspråket

import Data.Char (isUpper, toLower)

type Consonants = [Char]

robberEncode :: Consonants -> String -> String
robberEncode cons = concat . map mapper
  where mapper :: Char -> String
        mapper c
          | (toLower c) `elem` cons = [c, 'o', toLower c]
          | otherwise               = [c]

robberDecode :: Consonants -> String -> String
robberDecode cons [] = []
robberDecode cons (c:cs)
  | (toLower c) `elem` cons && length cs > 1 = c : robberDecode cons (drop 2 cs)
  | otherwise                                = c : robberDecode cons cs

swedishConsonants :: Consonants
swedishConsonants = "bcdfghjklmnpqrstvwxz"

englishConsonants :: Consonants
englishConsonants = swedishConsonants