flatten: drastically improve performance, see #17626

8 years ago · ebffa9fd06
parent 8955dc5e7e
commit ebffa9fd06
1 changed files with 1 additions and 1 deletions
--- a/lib/lists.nix
+++ b/lib/lists.nix
@ -89,7 +89,7 @@ rec {
  */
  flatten = x:
    if isList x
-    then foldl' (x: y: x ++ (flatten y)) [] x
+    then concatMap (y: flatten y) x
    else [x];

  /* Remove elements equal to 'e' from a list.  Useful for buildInputs.