add CCVector.to_seq_rev

src/core/CCVector.ml

@@ -531,6 +531,16 @@ let of_seq ?(init=create ()) seq =
 
 let to_seq v k = iter k v
 
+let to_seq_rev v k =
+  for i = v.size - 1 downto 0 do
+    k (Array.unsafe_get v.vec i)
+  done
+
+(*$Q
+  Q.(list int) (fun l -> \
+    let v= of_list l in v |> to_seq_rev |> Sequence.to_rev_list = l)
+*)
+
 let slice_seq v start len =
   assert (start >= 0 && len >= 0);
   fun k ->

src/core/CCVector.mli

@@ -225,6 +225,11 @@ val of_seq : ?init:('a,rw) t -> 'a sequence -> ('a, rw) t
 
 val to_seq : ('a,_) t -> 'a sequence
 
+val to_seq_rev : ('a, _) t -> 'a sequence
+(** [to_seq_rev v] returns the sequence of elements of [v] in reverse order,
+    that is, the last elements of [v] are iterated on first.
+    @since NEXT_RELEASE *)
+
 val slice : ('a,rw) t -> ('a array * int * int)
 (** Vector as an array slice. By doing it we expose the internal array, so
     be careful! *)