From 9bcc410c368420883457f6671ae8e7c1851e6398 Mon Sep 17 00:00:00 2001
From: Simon Cruanes <simon.cruanes.2007@m4x.org>
Date: Tue, 20 May 2014 20:10:09 +0200
Subject: [PATCH] better CCKlist.flat_map

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

diff --git a/core/CCKList.ml b/core/CCKList.ml
index a9a5fe81..897a9409 100644
--- a/core/CCKList.ml
+++ b/core/CCKList.ml
@@ -120,5 +120,9 @@ let rec append l1 l2 = match l1 with
 let rec flat_map f l = match l with
   | `Nil -> `Nil
   | `Cons (x, l') ->
-      append (f x) (flat_map f (l' ()))
+      _flat_map_app f (f x) (l' ()) ()
+and _flat_map_app f l l' () = match l with
+  | `Nil -> flat_map f l'
+  | `Cons (x, tl) ->
+      `Cons (x, _flat_map_app f (tl ()) l')