Suppose I have defined some data type that derives Eq but want to insert my own definition of (==) for some pattern. Is there any way to do this or do I have to define (==) for every pattern?
e.g.
data Asdf = One Char | Two Char Char --(deriving Eq)
instance Eq Asdf where
(==) (One _) (One _) = True
--otherwise use what the derived definition would have done
--can I do this without defining these patterns myself?