2 files changed, 10 insertions, 0 deletions
diff --git a/clib/cArray.ml b/clib/cArray.ml
index d509c55b9a..b9dcfd61d1 100644
--- a/clib/cArray.ml
+++ b/clib/cArray.ml
@@ -63,6 +63,7 @@ sig
   val fold_left_map : ('a -> 'b -> 'a * 'c) -> 'a -> 'b array -> 'a * 'c array
   val fold_right_map : ('a -> 'c -> 'b * 'c) -> 'a array -> 'c -> 'b array * 'c
   val fold_left2_map : ('a -> 'b -> 'c -> 'a * 'd) -> 'a -> 'b array -> 'c array -> 'a * 'd array
+  val fold_left2_map_i : (int -> 'a -> 'b -> 'c -> 'a * 'd) -> 'a -> 'b array -> 'c array -> 'a * 'd array
   val fold_right2_map : ('a -> 'b -> 'c -> 'd * 'c) -> 'a array -> 'b array -> 'c -> 'd array * 'c
   val fold_map : ('a -> 'b -> 'a * 'c) -> 'a -> 'b array -> 'a * 'c array
   [@@ocaml.deprecated "Same as [fold_left_map]"]
@@ -451,6 +452,11 @@ let fold_left2_map f e v1 v2 =
   let v' = map2 (fun x1 x2 -> let (e,y) = f !e' x1 x2 in e' := e; y) v1 v2 in
   (!e',v')
 
+let fold_left2_map_i f e v1 v2 =
+  let e' = ref e in
+  let v' = map2_i (fun idx x1 x2 -> let (e,y) = f idx !e' x1 x2 in e' := e; y) v1 v2 in
+  (!e',v')
+
 let distinct v =
   let visited = Hashtbl.create 23 in
   try
diff --git a/clib/cArray.mli b/clib/cArray.mli
index 5c7e09eeac..163191681a 100644
--- a/clib/cArray.mli
+++ b/clib/cArray.mli
@@ -114,6 +114,10 @@ sig
   val fold_left2_map : ('a -> 'b -> 'c -> 'a * 'd) -> 'a -> 'b array -> 'c array -> 'a * 'd array
   (** Same with two arrays, folding on the left; see also [Smart.fold_left2_map] *)
 
+  val fold_left2_map_i :
+    (int -> 'a -> 'b -> 'c -> 'a * 'd) -> 'a -> 'b array -> 'c array -> 'a * 'd array
+  (** Same than [fold_left2_map] but passing the index of the array *)
+
   val fold_right2_map : ('a -> 'b -> 'c -> 'd * 'c) -> 'a array -> 'b array -> 'c -> 'd array * 'c
   (** Same with two arrays, folding on the left *)