refactor(registry): reference uniqueness predicate directly

src/dotfiles/util.nix

@@ -16,20 +16,18 @@ let
           [ ]
       ) (builtins.readDir dir)
     );
-
-  uniqueValue =
-    value: entries: builtins.length (lib.unique (map value entries)) == builtins.length entries;
 in
-{
+rec {
   inherit collectNixFiles;
 
   removeNixSuffix = path: lib.removeSuffix ".nix" (builtins.baseNameOf path);
 
-  registry.predicates.uniqueValue = uniqueValue;
+  registry.predicates.uniqueValue =
+    value: entries: builtins.length (lib.unique (map value entries)) == builtins.length entries;
 
   registry.predicates.uniquePerHost =
     value:
-    uniqueValue (entry: {
+    registry.predicates.uniqueValue (entry: {
       inherit (entry) host;
       value = value entry;
     });