Section verif_expo.
Variable A B : Setoid.
(* B(expo A) = A==>B *)
Definition S_expo := Map A B.
(* de'finition de eval *)
Definition S_eval_fun (fxa : SPROD (A ==> B) A) := Sprod_l fxa (Sprod_r fxa).

Lemma S_eval_map_law : Map_law S_eval_fun.