* Add a function to take the last element of a list.

svn path=/nixpkgs/trunk/; revision=19179

pkgs/lib/lists.nix

@@ -167,4 +167,9 @@ rec {
     if list == [] || count == 0 then []
     else [ (head list) ] ++ take (builtins.sub count 1) (tail list);
 
+  last = list:
+    assert list != [];
+    let loop = l: if tail l == [] then head l else loop (tail l); in
+    loop list;
+
 }