From 4b5c1dec62395a662665067f14894bd64ba6de0f Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date: Thu, 14 Jun 2012 19:07:01 +0000
Subject: [PATCH] =?UTF-8?q?*=20Add=20a=20function=20=E2=80=98mapAttrsToLis?=
 =?UTF-8?q?t=E2=80=99=20that=20maps=20a=20function=20over=20the=20=20=20at?=
 =?UTF-8?q?tributes=20in=20a=20set,=20returning=20a=20list.=20=20(Note=20t?=
 =?UTF-8?q?hat=20the=20regular=20=20=20=E2=80=98mapAttrs=E2=80=99=20return?=
 =?UTF-8?q?s=20an=20attribute=20set.)?=
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svn path=/nixpkgs/trunk/; revision=34509
---
 pkgs/lib/attrsets.nix | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/pkgs/lib/attrsets.nix b/pkgs/lib/attrsets.nix
index 260c61558a4..5e4e9df3711 100644
--- a/pkgs/lib/attrsets.nix
+++ b/pkgs/lib/attrsets.nix
@@ -146,6 +146,18 @@ rec {
     listToAttrs (map (attr: f attr (getAttr attr set)) (attrNames set));
         
 
+  /* Call a function for each attribute in the given set and return
+     the result in a list.
+  
+     Example:
+       mapAttrsToList (name: value: name + value)
+          { x = "a"; y = "b"; }
+       => [ "xa" "yb" ]
+  */
+  mapAttrsToList = f: attrs:
+    map (name: f name (getAttr name attrs)) (attrNames attrs);
+    
+
   /* Like `mapAttrs', except that it recursively applies itself to
      attribute sets.  Also, the first argument of the argument
      function is a *list* of the names of the containing attributes.