Add shuffle.

sequence.ml

@@ -707,6 +707,11 @@ let shuffle_array a =
     a.(k) <- tmp;
   done
 
+let shuffle seq =
+  let a = to_array seq in
+  shuffle_array a ;
+  of_array a
+
 let shuffle_buffer n seq k =
   let seq_front = take n seq in
   let a = to_array seq_front in

sequence.mli

@@ -498,6 +498,11 @@ val random_list : 'a list -> 'a t
 (** Infinite sequence of random elements of the list. Basically the
     same as {!random_array}. *)
 
+val shuffle : 'a t -> 'a t
+(** [shuffle seq] returns a perfect shuffle of [seq].
+    Uses O(length seq) memory and time. Eager.
+    @since NEXT_RELEASE *)
+
 val shuffle_buffer : int -> 'a t -> 'a t
 (** [shuffle_buffer n seq] returns a sequence of element of [seq] in random
     order. The shuffling is *not* uniform. Uses O(n) memory.

sequenceLabels.mli

@@ -446,6 +446,11 @@ val random_list : 'a list -> 'a t
 (** Infinite sequence of random elements of the list. Basically the
     same as {!random_array}. *)
 
+val shuffle : 'a t -> 'a t
+(** [shuffle seq] returns a perfect shuffle of [seq].
+    Uses O(length seq) memory and time. Eager.
+    @since NEXT_RELEASE *)
+
 val shuffle_buffer : n:int -> 'a t -> 'a t
 (** [shuffle_buffer n seq] returns a sequence of element of [seq] in random
     order. The shuffling is not uniform. Uses O(n) memory.