Adding a coiterator to IStream.

2 files changed, 9 insertions, 0 deletions

diff --git a/lib/iStream.ml b/lib/iStream.ml
index da54d9f7b8..36b9c43ad0 100644
--- a/lib/iStream.ml
+++ b/lib/iStream.ml
@@ -20,6 +20,12 @@ let cons x s = Lazy.lazy_from_val (Cons (x, s))
 
 let thunk = Lazy.lazy_from_fun
 
+let rec make_node f s = match f s with
+| Nil -> Nil
+| Cons (x, s) -> Cons (x, make f s)
+
+and make f s = lazy (make_node f s)
+
 let rec force s = match Lazy.force s with
 | Nil -> ()
 | Cons (_, s) -> force s
diff --git a/lib/iStream.mli b/lib/iStream.mli
index 61967f49e4..a059570107 100644
--- a/lib/iStream.mli
+++ b/lib/iStream.mli
@@ -31,6 +31,9 @@ val cons : 'a -> 'a t -> 'a t
 val thunk : (unit -> ('a,'a t) u) -> 'a t
 (** Internalize the lazyness of a stream. *)
 
+val make : ('a -> ('b, 'a) u) -> 'a -> 'b t
+(** Coiteration constructor. *)
+
 (** {6 Destructors} *)
 
 val is_empty : 'a t -> bool