diff --git a/lib/default.nix b/lib/default.nix
new file mode 100644
index 0000000..1cbd641
--- /dev/null
+++ b/lib/default.nix
@@ -0,0 +1,24 @@
+{ lib, ... }:
+{
+  # use path relative to the root of the project
+  relativeToRoot = lib.path.append ../.;
+  scanPaths = path:
+    builtins.map
+      (f: (path + "/${f}"))
+      (builtins.attrNames
+        (lib.attrsets.filterAttrs
+          (
+            path: _type:
+              (_type == "directory") # include directories
+              || (
+                # FIXME this barfs when child directories don't contain a default.nix
+                # example:
+                # error: getting status of '/nix/store/mx31x8530b758ap48vbg20qzcakrbc8 (see hosts/common/core/services/default.nix)a-source/hosts/common/core/services/default.nix': No such file or directory
+                # I created a blank default.nix in hosts/common/core/services to work around
+                (path != "default.nix") # ignore default.nix
+                && (lib.strings.hasSuffix ".nix" path) # include .nix files
+              )
+          )
+          (builtins.readDir path)));
+}
+