Say I have code already like:

data STH = A

        | B

        | C

instance Serialize STH where

  put A = putWord8 1

  put B = putWord8 66

  put C = putWord8 111

Then what is the better way to do `get`? Is following the only one?

get = do

  i <- getWord8

  case i of

    1 -> return A

    66 -> return B

    111 -> return C

Thanks.