proposition: Lemma isaset_retraction (A B : ob C) (H : has_homsets C) : isaset (retraction A B).
proof: Proof. do 2 (apply isaset_total2; [apply H | intro]). apply isasetaprop. apply isaprop_is_retraction. apply H. Qed.
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Functors