add Array.append

src/core/CCArray.ml

@@ -490,6 +490,25 @@ let filter_map f a =
 let filter p a =
   filter_map (fun x -> if p x then Some x else None) a
 
+let append a1 a2 =
+  let n1 = Array.length a1 in
+  let n2 = Array.length a2 in
+  if n1=0 then a2
+  else if n2=0 then a1
+  else (
+    let res = Array.make (n1+n2) a1.(0) in
+    Array.blit a1 0 res 0 n1;
+    Array.blit a2 0 res n1 n2;
+    res
+  )
+
+(*$= & ~printer:Q.Print.(array int)
+  [| 1;2;3;4 |] (append [|1;2|] [| 3;4 |])
+  [| 1;2;3;4 |] (append [||] [| 1;2; 3;4 |])
+  [| 1;2;3;4 |] (append [| 1;2; 3;4 |] [||])
+  [||] (append [||] [||])
+*)
+
 (* append [rev a] in front of [acc] *)
 let rec __rev_append_list a acc i =
   if i = Array.length a

src/core/CCArray.mli

@@ -187,6 +187,10 @@ val rev : 'a t -> 'a t
 (** Copy + reverse in place
     @since 0.20 *)
 
+val append : 'a t -> 'a t -> 'a t
+(** Append 2 arrays
+    @since NEXT_RELEASE *)
+
 val filter : ('a -> bool) -> 'a t -> 'a t
 (** Filter elements out of the array. Only the elements satisfying
     the given predicate will be kept. *)