From 6408a6a6fd7886a55dd681e0875c79a84516c8f3 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date: Mon, 8 Jun 2009 22:42:42 +0000
Subject: [PATCH] * Trivial function to create a singleton list.  Can reduce
 unnecessary   indentation in expressions like

    environent.extraJobs =
      [ { name = "foo";
          job =
            ''
              bla bla
            '';
        }
      ];

  which becomes

    environent.extraJobs = singleton
      { name = "foo";
        job =
          ''
            bla bla
          '';
      };

svn path=/nixpkgs/trunk/; revision=15892
---
 pkgs/lib/lists.nix | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/pkgs/lib/lists.nix b/pkgs/lib/lists.nix
index b186e97a55b..8ac93476a53 100644
--- a/pkgs/lib/lists.nix
+++ b/pkgs/lib/lists.nix
@@ -4,6 +4,12 @@ rec {
   inherit (builtins) head tail isList;
 
 
+  # Create a list consisting of a single element.  `singleton x' is
+  # sometimes more convenient with respect to indentation than `[x]'
+  # when x spans multiple lines.
+  singleton = x: [x];
+  
+
   # "Fold" a binary function `op' between successive elements of
   # `list' with `nul' as the starting value, i.e., `fold op nul [x_1
   # x_2 ... x_n] == op x_1 (op x_2 ... (op x_n nul))'.  (This is