Category "deriving"

Alternative of Show that only uses name

Is there something like Show (deriving Show) that only uses an algebraic datatype's constructors? (please don't mind that I'm using the word constructor, I don'

Haskell Monoid Instance Question for a newtype

I am trying to define an instance: newtype Join a = Join { getJoin :: a -> Bool } deriving Generic instance Monoid (Join a) where f <> g = ???