[Haskell-cafe] Deriving

What happens when a type adds driving such as: newtype SupplyT s m a = SupplyT (StateT [s] m a) deriving (Functor <http://haskell.org/ghc/docs/latest/html/libraries/base/Prelude.html#t:Functor>, Monad <http://haskell.org/ghc/docs/latest/html/libraries/base/Prelude.html#t:Monad>, MonadTrans, MonadIO) Two questions: How does the deriving implement the instance? Is there a way for me to add my own classes in the deriving? for example newtype ..... deriving( xyz) Thanks