More efficient version of filterAttrs

9 years ago · 3cd5fd8bb3
parent 2b2e7c2730
commit 3cd5fd8bb3
1 changed files with 1 additions and 1 deletions
--- 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: