proposition: Lemma length_zero_inv : forall l, length l = 0%nat -> l = nil.
proof: Proof. Proof using. intros l. destruct l; rew_list; introv E. { auto. } { false. } Qed.
imports: Coq.Classes.Morphisms TLC(LibTactics LibLogic LibReflect LibOperation LibProd LibOption LibNat LibInt LibWf LibMonoid LibRelation)