From e528b920bb1fcc616179f5dbd93889ccc6b32329 Mon Sep 17 00:00:00 2001
From: Nicolas Pierron <nicolas.b.pierron@gmail.com>
Date: Tue, 6 Oct 2009 13:36:46 +0000
Subject: [PATCH] Add the reverseList function.

svn path=/nixpkgs/trunk/; revision=17676
---
 pkgs/lib/lists.nix | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/pkgs/lib/lists.nix b/pkgs/lib/lists.nix
index 785e47e7d523..d032ab412bab 100644
--- a/pkgs/lib/lists.nix
+++ b/pkgs/lib/lists.nix
@@ -136,4 +136,10 @@ rec {
 
   zipLists = zipListsWith (fst: snd: { inherit fst snd; });
 
+  # invert the order of the elements of a list.
+  reverseList = l:
+    let reverse_ = accu: l:
+      if l == [] then accu
+      else reverse_ ([(head l)] ++ accu) (tail l);
+    in reverse_ [] l;
 }