Merge commit 'b3c692172e5b5241b028a98e1977f9fb12eeaf42'

1 files changed, 12 insertions, 9 deletions

diff --git a/nixpkgs/lib/attrsets.nix b/nixpkgs/lib/attrsets.nix
index 5c787940cb0c..31fddc59e20e 100644
--- a/nixpkgs/lib/attrsets.nix
+++ b/nixpkgs/lib/attrsets.nix
@@ -5,7 +5,7 @@ let
   inherit (builtins) head tail length;
   inherit (lib.trivial) and;
   inherit (lib.strings) concatStringsSep sanitizeDerivationName;
-  inherit (lib.lists) fold concatMap concatLists;
+  inherit (lib.lists) foldr foldl' concatMap concatLists elemAt;
 in
 
 rec {
@@ -55,10 +55,13 @@ rec {
        => { a = { b = 3; }; }
   */
   setAttrByPath = attrPath: value:
-    if attrPath == [] then value
-    else listToAttrs
-      [ { name = head attrPath; value = setAttrByPath (tail attrPath) value; } ];
-
+    let
+      len = length attrPath;
+      atDepth = n:
+        if n == len
+        then value
+        else { ${elemAt attrPath n} = atDepth (n + 1); };
+    in atDepth 0;
 
   /* Like `attrByPath' without a default value. If it doesn't find the
      path it will throw.
@@ -152,8 +155,8 @@ rec {
        => { a = [ 2 3 ]; }
   */
   foldAttrs = op: nul: list_of_attrs:
-    fold (n: a:
-        fold (name: o:
+    foldr (n: a:
+        foldr (name: o:
           o // { ${name} = op n.${name} (a.${name} or nul); }
         ) a (attrNames n)
     ) {} list_of_attrs;
@@ -195,7 +198,7 @@ rec {
          ]
   */
   cartesianProductOfSets = attrsOfLists:
-    lib.foldl' (listOfAttrs: attrName:
+    foldl' (listOfAttrs: attrName:
       concatMap (attrs:
         map (listValue: attrs // { ${attrName} = listValue; }) attrsOfLists.${attrName}
       ) listOfAttrs
@@ -455,7 +458,7 @@ rec {
        => true
    */
   matchAttrs = pattern: attrs: assert isAttrs pattern;
-    fold and true (attrValues (zipAttrsWithNames (attrNames pattern) (n: values:
+    foldr and true (attrValues (zipAttrsWithNames (attrNames pattern) (n: values:
       let pat = head values; val = head (tail values); in
       if length values == 1 then false
       else if isAttrs pat then isAttrs val && matchAttrs pat val