proposition: Lemma map_concat `(f : a → b) `(xs : t (t a n) m) : map f (concat xs) = concat (map (map f) xs).
proof: Proof. induction xs; simpl; auto. rewrite <- IHxs. now apply map_append. Qed.
imports: Category.Lib Category.Theory.Category Category.Theory.Isomorphism Category.Theory.Functor Category.Theory.Adjunction Category.Structure.Terminal Category.Structure.Cartesian Category.Structure.BiCCC Category.Instance.Fun Category.Instance.Coq Category.Instance.Sets Coq.Vectors.Vector