Section EqlistA.
Global Instance app_eqlistA_compat :
Proper (eqlistA==>eqlistA==>eqlistA) (@app A).

(** For compatibility, can be deduced from app_eqlistA_compat **)
Lemma eqlistA_app : forall l1 l1' l2 l2',
eqlistA l1 l1' -> eqlistA l2 l2' -> eqlistA (l1++l2) (l1'++l2').