some cleanup

lib.nix

@@ -1,7 +1,7 @@
 { lib, ... }:
 with builtins;
-let
-  walk-dir-inner =
+rec {
+  walk-dir =
     path:
     let
       dir = readDir path;
@@ -12,18 +12,8 @@ let
         if value == "regular" then
           path + "/${filename}"
         else if value == "directory" then
-          walk-dir-inner (path + "/${filename}")
+          walk-dir (path + "/${filename}")
         else
           throw "Items of type ${value} are unsupported.";
     }) dir;
-
-  helper-attrs = subpaths: {
-    _map = f: lib.mapAttrsRecursive (_: f) subpaths;
-  };
-
-  with-helper-attrs =
-    x: if isAttrs x then lib.mapAttrs (_: with-helper-attrs) x // helper-attrs x else x;
-in
-{
-  walk-dir = p: with-helper-attrs (walk-dir-inner p);
 }