+instance Uniquable PackageId where
+ getUnique pid = getUnique (packageIdFS pid)
+
+-- Note: *not* a stable lexicographic ordering, a faster unique-based
+-- ordering.
+instance Ord PackageId where
+ nm1 `compare` nm2 = getUnique nm1 `compare` getUnique nm2
+
+stablePackageIdCmp :: PackageId -> PackageId -> Ordering
+-- ^ Compares package ids lexically, rather than by their 'Unique's
+stablePackageIdCmp p1 p2 = packageIdFS p1 `compare` packageIdFS p2
+