From fe22f3f45f431de636c887d0e114eca3a7fc63c2 Mon Sep 17 00:00:00 2001
From: Daniel Olsen <daniel.olsen99@gmail.com>
Date: Sun, 26 Nov 2023 08:23:03 +0100
Subject: [PATCH 1/2] lib/tests: Add test for genAttrs

---
 lib/tests/misc.nix | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/tests/misc.nix b/lib/tests/misc.nix
index 06cb5e763e2c2..137f06c4e7d31 100644
--- a/lib/tests/misc.nix
+++ b/lib/tests/misc.nix
@@ -785,6 +785,10 @@ runTests {
     };
   };
 
+  testGenAttrs = {
+    expr = attrsets.genAttrs [ "foo" "bar" ] (name: "${name}123");
+    expected = { foo = "foo123"; bar = "bar123"; };
+  };
 
   testMergeAttrsListExample1 = {
     expr = attrsets.mergeAttrsList [ { a = 0; b = 1; } { c = 2; d = 3; } ];

From 7bbba3ffda2c9dc5f674e01ce169b1b56d6fce5d Mon Sep 17 00:00:00 2001
From: Daniel Olsen <daniel.olsen99@gmail.com>
Date: Sun, 26 Nov 2023 13:22:09 +0100
Subject: [PATCH 2/2] lib/attrsets: add genAttrs'

---
 lib/attrsets.nix   | 14 ++++++++++++++
 lib/tests/misc.nix |  7 +++++++
 2 files changed, 21 insertions(+)

diff --git a/lib/attrsets.nix b/lib/attrsets.nix
index bf6c90bf1be60..afb8362f0de19 100644
--- a/lib/attrsets.nix
+++ b/lib/attrsets.nix
@@ -651,6 +651,20 @@ rec {
     f:
     listToAttrs (map (n: nameValuePair n (f n)) names);
 
+  /* Generate an attribute set by mapping over a list of items
+     Taking two functions, one to apply for the name and one to
+     apply for the value of the attribute set.
+
+    Example:
+       genAttrs' [ {a = 2; b.c = "a" } {a = 1; b.c = "b"} ]
+          (i: i.b.c) (i: i.a)
+       => { a = 2; b = 1; }
+
+    Type:
+      genAttrs' :: [ a ] -> (a -> String) -> (a -> Any) -> AttrSet
+  */
+  genAttrs' = items: f: g:
+    listToAttrs (map (i: nameValuePair (f i) (g i)) items);
 
   /* Check whether the argument is a derivation. Any set with
      `{ type = "derivation"; }` counts as a derivation.
diff --git a/lib/tests/misc.nix b/lib/tests/misc.nix
index 137f06c4e7d31..033ac44091976 100644
--- a/lib/tests/misc.nix
+++ b/lib/tests/misc.nix
@@ -789,6 +789,13 @@ runTests {
     expr = attrsets.genAttrs [ "foo" "bar" ] (name: "${name}123");
     expected = { foo = "foo123"; bar = "bar123"; };
   };
+  testGenAttrsPrime = {
+    expr = attrsets.genAttrs' [ { foo = "a"; bar = "b"; } { foo = "c"; bar = "d"; } ] (x: x.foo) (x: "${toString x.foo}${toString x.bar}");
+    expected = {
+      a = "ab";
+      c = "cd";
+    };
+  };
 
   testMergeAttrsListExample1 = {
     expr = attrsets.mergeAttrsList [ { a = 0; b = 1; } { c = 2; d = 3; } ];