Thanks everyone. So there is agreement on having Applicative and Monoid instances, and on not having additional helpers for generic deriving. That's fine to me. Replying to Ryan:
3. Add Monoid instances
I think I support this idea. But just to be sure we're on the same page: can you say which instances in particular you're adding, and how you'd implement them?
The main Monoid instances would be: Monoid (f p) => Monoid (M1 i c f p) -- newtype-derived Monoid a => Monoid (K1 i a p) -- newtype-derived (Monoid (f p), Monoid (g p)) => Monoid ((f :*: g) p) -- product monoid Monoid (U1 p) -- unit-like No instance for (:+:). Now that you mention it, I'm not sure about adding Monoid instances for the type constructors involved in Generic1, they would be (all newtype-derived): Monoid p => Monoid (Par1 p) Monoid (f p) => Monoid (Rec1 f p) Monoid (f (g p)) => Monoid ((f :.: g) p) Is ther an opinion against that? I forgot to mention Semigroup instances. They would follow the same structure, and for completeness we can also have Semigroup (V1 p) This enables a more general "generic semigroup" than via Applicative. Li-yao