NAryFunctor
class NFunctor f
class VarianceTransformer t a
data CovariantT to f f'
data Covariant1T to f f'
data ContravariantT to f f'
data Contravariant1T to f f'
data InvariantT to f f'
data Invariant1T to f f'
data NonvariantT to f f'
data PhantomvariantT to f f'