(nf : NaiveNondepFunext) {A B C : Type} (f : B <~> C) : (A -> B) <~> (A -> C) := Build_Equiv _ _ (fun (g:A->B) => f o g) (isequiv_adjointify (fun (g:A->B) => f o g) (fun h => f^-1 o h) (fun h => nf _ _ _ _ (fun x => eisretr f (h x))) (fun g => nf _ _ _ _ (fun y => eissect f (g y)))).
Require Import HoTT.Basics HoTT.Types. Require Import Metatheory.Core.