commit 498263096784c9857cf714050ba9d21f81df073e
Author: Simon Cruanes <simon.cruanes.2007@m4x.org>
Date:   Sun Jan 27 23:17:29 2013 +0100

    sequence type

diff --git a/sequence.ml b/sequence.ml
new file mode 100644
index 0000000..4e0afaf
--- /dev/null
+++ b/sequence.ml
@@ -0,0 +1,31 @@
+
+(** {2 Transient iterators, that abstract on a finite sequence of elements. *)
+
+(** Sequence abstract iterator type *)
+type 'a sequence = {
+  seq_fun: ('a -> unit) -> unit;
+}
+
+(** Build a sequence from a iter function *)
+let from_iter f = {
+  seq_fun = f;
+}
+
+(** Consume the sequence, passing all its arguments to the function *)
+let iter f seq = seq.seq_fun f
+
+(** Fold over elements of the sequence, consuming it *)
+let fold f init seq =
+  let r = ref init in
+  seq.seq_fun (fun elt -> r := f !r elt);
+  !r
+    
+(** Map objects of the sequence into other elements, lazily *)
+let map f seq =
+  let seq_fun' k = seq.seq_fun (fun x -> k (f x)) in
+  { seq_fun=seq_fun'; }
+
+(** Filter on elements of the sequence *)
+let filter p seq =
+  let seq_fun' k = seq.seq_fun (fun x -> if p x then k x) in
+  { seq_fun=seq_fun'; }
diff --git a/sequence.mli b/sequence.mli
new file mode 100644
index 0000000..7c4f7f4
--- /dev/null
+++ b/sequence.mli
@@ -0,0 +1,20 @@
+
+(** {2 Transient iterators, that abstract on a finite sequence of elements. *)
+
+type 'a sequence
+  (** Sequence abstract iterator type *)
+
+val from_iter : (('a -> unit) -> unit) -> 'a sequence
+  (** Build a sequence from a iter function *)
+
+val iter : ('a -> unit) -> 'a sequence -> unit
+  (** Consume the sequence, passing all its arguments to the function *)
+
+val fold : ('b -> 'a -> 'b) -> 'b -> 'a sequence -> 'b
+  (** Fold over elements of the sequence, consuming it *)
+
+val map : ('a -> 'b) -> 'a sequence -> 'b sequence
+  (** Map objects of the sequence into other elements, lazily *)
+
+val filter : ('a -> bool) -> 'a sequence -> 'a sequence
+  (** Filter on elements of the sequence *)