2009/7/16 Szekeres István
class ListUpdater a where updateFn :: Char -> Char update :: a -> a
so I can define the update function for the different types of lists:
instance ListUpdater String where update = map updateFn
instance ListUpdater L.ByteString where update = L.pack . (map updateFn) . L.unpack
So, as written, these functions both give an error, because updateFn isn't defined. Perhaps you want something like this:
class CharMap a where charMap :: (Char -> Char) -> (a -> a) instance CharMap Char where charMap f = f instance CharMap a => CharMap [a] where charMap f = map (charMap f) instance CharMap L.ByteString where charMap f = L.pack . map f . L.unpack
Now you can write
genericRot13, genericUL :: CharMap a => a -> a genericRot13 = charMap rot13 genericUL = charMap ul
-- ryan