import qualified Data.ByteString.Char8 as B
import qualified Data.ByteString.Lazy.Char8 as L

class PackChar8 s where
  pack :: String -> s
  unpack :: s -> String

instance PackChar8 B.ByteString where
  pack = B.pack
  unpack = B.unpack

instance PackChar8 L.ByteString where
  pack = L.pack
  unpack = L.unpack


id :: (PackChar8 p) => p -> p
id = pack . unpack