Add modules

modules/home-manager.nix

@@ -0,0 +1,59 @@
+# Licensed under GNU Lesser General Public License v3 or later, see COPYING.
+# Copyright (c) 2019 Alexander Sosedkin and other contributors, see AUTHORS.
+
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.home-manager;
+
+  hmModule = types.submodule ({ name, ... }: {
+    imports = import <home-manager/modules/modules.nix> { inherit lib pkgs; };
+
+    config = {
+      submoduleSupport.enable = true;
+      submoduleSupport.externalPackageInstall = cfg.useUserPackages;
+
+      home.username = config.user.userName;
+      home.homeDirectory = config.user.home;
+    };
+  });
+in
+
+{
+
+  ###### interface
+
+  options = {
+
+    home-manager = {
+      config = mkOption {
+        type = types.nullOr hmModule;
+        default = null;
+        description = "Home Manager configuration.";
+      };
+
+      useUserPackages = mkEnableOption ''
+        installation of user packages through the
+        <option>environment.packages</option> option.
+      '';
+    };
+
+  };
+
+
+  ###### implementation
+
+  config = mkIf (cfg.config != null) {
+
+    inherit (config) assertions warnings;
+
+    build.activation.homeManager = ''
+      ${cfg.config.home.activationPackage}/activate
+    '';
+
+    environment.packages = mkIf cfg.useUserPackages cfg.config.home.packages;
+
+  };
+}