Section Elt.
Variable elt:Type.
Definition Add x (e:elt) m m' := forall y, find y m' = find y (add x e m).
Notation eqke := (@eq_key_elt elt).
Notation eqk := (@eq_key elt).
Instance eqk_equiv : Equivalence eqk.
(** Complements about InA, NoDupA and findA *)
(** * Elements *)
(** * Conversions between maps and association lists. *)
Definition uncurry {U V W : Type} (f : U -> V -> W) : U*V -> W :=
fun p => f (fst p) (snd p).
Definition of_list :=
List.fold_right (uncurry (@add _)) (empty elt).
Definition to_list := elements.

Lemma of_list_3 : forall s, Equal (of_list (to_list s)) s.