proposition: Lemma exp_sigT_iso : forall A (P : A -> Type) r, { x : A & P x } -> r ≅ (forall x : A, P x -> r).
proof: Proof. intros. exists (fun p x H => p (existT _ x H)). exists (fun k p => match p with existT x H => k x H end). extensionalize. 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