Add Forall2_map_map_iff

1 files changed, 7 insertions, 0 deletions

diff --git a/src/Util/ListUtil/Forall.v b/src/Util/ListUtil/Forall.v
index ffc6ca9e9..d9adfffa6 100644
--- a/src/Util/ListUtil/Forall.v
+++ b/src/Util/ListUtil/Forall.v
@@ -79,6 +79,13 @@ Proof using Type.
   revert ls2; induction ls1 as [|l ls IHls], ls2 as [|l' ls'];
     t_Forall2.
 Qed.
+Lemma Forall2_map_map_iff {A A' B B' R f g ls1 ls2}
+  : @List.Forall2 A' B' R (List.map f ls1) (List.map g ls2)
+    <-> @List.Forall2 A B (fun x y => R (f x) (g y)) ls1 ls2.
+Proof using Type.
+  revert ls2; induction ls1 as [|l ls IHls], ls2 as [|l' ls'];
+    t_Forall2.
+Qed.
 Lemma Forall2_Forall {A R ls}
   : @List.Forall2 A A R ls ls
     <-> @List.Forall A (Proper R) ls.