Runtime Dependency Resolution ( by a haskell noob )

gistfile1.hs

import qualified Data.Map as Map   
import Data.List
import Control.Applicative 

englishTranslator = ("ENGLISH: " ++)
germanTranslator = ("GERMAN: " ++)

windowsUnlines = intercalate "\r\n"
unixUnlines = intercalate "\n"

translators = Map.fromList [
  ("english",englishTranslator),
  ("german",germanTranslator)
  ]

unliners = Map.fromList [
  ("windows",windowsUnlines),
  ("unix",unixUnlines)
  ]

processString :: ([String] -> String) -> ( String -> String ) -> [String] -> String 
processString unliner translator = translator . unliner

makeStringProcessor osType language =
  let 
    unliner = Map.lookup osType unliners
    translator = Map.lookup language translators
  in
   case processString <$> unliner <*> translator of
     Nothing -> error $ intercalate "" [
       "Cannot construct processor for os '",
       osType,
       "' and language '",
       language,
       "'"
       ]
     Just f -> f