proposition: Lemma big_mkcond (I : eqType) (r : seq I) (P : pred I) (F : I -> X) : \big[*%M/1]_(i <- r | P i) F i ≡ \big[*%M/1]_(i <- r) (if P i then F i else 1).
proof: Proof. rewrite unlock. elim: r => //= i r H. by case P; rewrite H ?monUl. Qed.
imports: HB(structures) Coq(RelationClasses Morphisms Relation_Definitions) mathcomp(all_ssreflect)