From fba4a5db9769b3d31256d840923d76335adb64ba Mon Sep 17 00:00:00 2001
From: Arnaud Spiwack
Date: Mon, 24 Feb 2014 17:06:42 +0100
Subject: IStream: more efficient implementation of concat_map.

---
 lib/iStream.ml | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

(limited to 'lib')

diff --git a/lib/iStream.ml b/lib/iStream.ml
index bcb5336f23..065155f081 100644
--- a/lib/iStream.ml
+++ b/lib/iStream.ml
@@ -77,4 +77,8 @@ let rec concat_node = function
 and concat (s : 'a t t) =
   lazy (concat_node (Lazy.force s))
 
-let concat_map f l = concat (map f l)
+let rec concat_map_node f = function
+| Nil -> Nil
+| Cons (x,s) -> app_node (Lazy.force (f x)) (concat_map f s)
+
+and concat_map f l = lazy (concat_map_node f (Lazy.force l))
-- 
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