proposition: Theorem Yoneda_iso : forall `{FunctorLaws f} a, Yoneda f a ≅ f a.
proof: Proof. intros. exists (fun k => k _ id). exists (fun x _ f => fmap f x). extensionalize. rewrite fmap_id0; trivial. Import YonedaLaws. exact (Yoneda_parametricity _ _ _ _ _ _). Qed.
imports: Hask.Ltac Hask.Prelude Hask.Control.Applicative Hask.Control.Monad Hask.Control.Monad.Cont Hask.Control.Monad.State Hask.Data.Functor.Contravariant Hask.Data.Functor.Identity Hask.Data.Functor.Kan Hask.Data.Functor.Yoneda Hask.Control.Lens Coq.Classes.Morphisms Coq.Setoids.Setoid Coq.Init.Datatypes Coq.Relations.Relation_Definitions FunctionalExtensionality