trying something?

lib/builders.nix

@@ -9,11 +9,13 @@ let
   });
 
   lib = nixpkgs.lib;
+  libExt = import ./. lib;
 
   inherit (inputs.home-manager.lib) homeManagerConfiguration;
   inherit (lib) nixosSystem;
   inherit (lib.strings) optionalString;
   inherit (lib.attrsets) nameValuePair;
+  inherit (libExt) right;
 in
 rec {
   toPartialNixosConfig =
@@ -32,7 +34,7 @@ rec {
       });
   compileSystems =
     systems:
-    lib.right
+    right
       builtins.listToAttrs
       (map toPartialNixosConfig)
       systems;
@@ -56,7 +58,7 @@ rec {
       });
   compileHomes =
     systems:
-    lib.right
+    right
       builtins.listToAttrs
       (map toPartialHomeManagerConfig)
       systems;

lib/default.nix

@@ -1,7 +1,4 @@
-final: prev:
-let
-  inherit (final) isFunction;
-in
+lib:
 rec {
   # Ternary operator
   # Exaample:
@@ -12,7 +9,7 @@ rec {
   # Right-associate and chain following single-operand functions
   # Example:
   # right f g h 1 => f(g(h(1)))
-  right = f: g: tern (isFunction g)
+  right = f: g: tern (lib.isFunction g)
     (right (x: f (g (x))))
     (f (g));
 }

lib/overlay.nix

@@ -0,0 +1,2 @@
+final: prev:
+(import ./. { lib = prev; })

pkgs/default.nix

@@ -3,7 +3,7 @@ let
   callDefaultPackage = path: prev.callPackage path { };
 in
 {
-  lib = prev.lib.extend import ../lib;
+  lib = prev.lib.extend import ../lib/overlay.nix;
 
   wrapWine = callDefaultPackage ./wrapWine;
   writeXrandrScriptBin = callDefaultPackage ./writeXrandrScriptBin;