flake.nix: remove unused specialArgs

flake.nix

@@ -54,7 +54,6 @@
     in (nixosSystem {
       # by default the local system is the same as the target, employing emulation when they differ
       system = target;
-      specialArgs = { inherit mobile-nixos home-manager impermanence; };
       modules = [
         ./modules
         (import ./hosts/instantiate.nix name)

modules/lib/default.nix

@@ -0,0 +1,21 @@
+{ lib, utils, ... }:
+
+rec {
+  path = {
+    # split the string path into a list of string components.
+    # root directory "/" becomes the empty list [].
+    # implicitly performs normalization so that:
+    # split "a//b/" => ["a" "b"]
+    # split "/a/b" =>  ["a" "b"]
+    split = str: builtins.filter (seg: (builtins.isString seg) && seg != "" ) (builtins.split "/" str);
+    # return a string path, with leading slash but no trailing slash
+    joinAbs = comps: "/" + (builtins.concatStringsSep "/" comps);
+    concat = paths: path.joinAbs (builtins.concatLists (builtins.map path.split paths));
+    # normalize the given path
+    norm = str: path.joinAbs (path.split str);
+    # return the parent directory. doesn't care about leading/trailing slashes.
+    # the parent of "/" is "/".
+    parent = str: path.norm (builtins.dirOf (path.norm str));
+    hasParent = str: (path.parent str) != (path.norm str);
+  };
+}