(MkSet set_1) == (MkSet set_2) = set_1 == set_2
(MkSet set_1) /= (MkSet set_2) = set_1 /= set_2
+instance Show e => Show (Set e) where
+ showsPrec p s = showsPrec p (setToList s)
+
-- but not so clear what the right thing to do is:
{- NO:
instance (Ord a) => Ord (Set a) where