Make pkgsets accessible to service configurations.

pkgs/systemPackages.nix

@@ -0,0 +1,16 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.machine;
+in {
+  environment.systemPackages = flatten (attrVals cfg.pkgs pkgs.pkgsets);
+
+  services.emacs = mkIf (elem "emacs" cfg.pkgs) {
+    defaultEditor = true;
+    enable = true;
+    install = true;
+    package = pkgs.pkgsets.emacs;
+  };
+}