proposition: Lemma sumList_body_const : forall (A : Set)(ls : list A) c, sumList ls (fun a => c) == c * (length ls / 1).
proof: Proof. intuition. eapply eqRat_trans. apply fold_add_body_const. rewrite <- ratAdd_0_r. eapply eqRat_refl. Qed.
imports: FCF.Rat List Permutation Arith FCF.EqDec FCF.StdNat Bool