firstorder...
- eapply evaluates_star in H as []...
- eapply star_evaluates... eapply equiv_star_lam...
Qed.

(* Specifications: *)
Lemma equiv_evaluates s t v : s ≡ t -> s ▷ v -> t ▷ v.
Instance evaluates_proper :
Proper (equiv ==> eq ==> iff) evaluates.