From 3cd5fd8bb3fc4b824e89cb800716989a332f20f1 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date: Thu, 23 Jul 2015 16:12:25 +0200
Subject: More efficient version of filterAttrs

---
 lib/attrsets.nix | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'lib/attrsets.nix')

diff --git a/lib/attrsets.nix b/lib/attrsets.nix
index cb4091b916c5..d81d69b14025 100644
--- a/lib/attrsets.nix
+++ b/lib/attrsets.nix
@@ -76,7 +76,7 @@ rec {
        => { foo = 1; }
   */
   filterAttrs = pred: set:
-    listToAttrs (fold (n: ys: let v = set.${n}; in if pred n v then [(nameValuePair n v)] ++ ys else ys) [] (attrNames set));
+    listToAttrs (concatMap (name: let v = set.${name}; in if pred name v then [(nameValuePair name v)] else []) (attrNames set));
 
 
   /* foldAttrs: apply fold functions to values grouped by key. Eg accumulate values as list:
-- 
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