Add new flake.nix file

flake.nix

@@ -1,34 +1,61 @@
 {
+  description = "NixOS configuration";
+
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-20.03";
     unstable.url = "github:nixos/nixpkgs/nixos-unstable";
-    home.url = "github:rycee/home-manager/bqv-flakes";
+    home-manager.url = "github:rycee/home-manager";
     emacs.url = "github:nix-community/emacs-overlay";
     hardware.url = "github:NixOS/nixos-hardware";
   };
 
-  outputs = { self, nix, ... }@inputs: {
-    nixosConfigurations.nixos = inputs.nixpkgs.lib.nixosSystem {
-      system = "x86_64-linux";
-      modules = [
-       { 
-         nixpkgs.overlays = [ inputs.emacs.overlay ];
-         system.configurationRevision = 
-           if self ? rev
-           then self.rev
-           else throw "Refusing to build from a dirty Git tree!";
-       }
-
-       inputs.hardware.nixosModules.lenovo-thinkpad-x220
-       (import ./hosts/thinkpad-x220)
-
-       inputs.home.nixosModules.home-manager
-       (import ./modules/home.nix)
-
-       inputs.nixpkgs.nixosModules.notDetected
-      ];
-      specialArgs = { inherit inputs; };
+  outputs = inputs: {
+    nixosConfigurations = {
+      hostname = let
+        system = "x86_64-linux";
+        pkgs = inputs.nixpkgs.legacyPackages.${system};
+        inherit (inputs.nixpkgs) lib;
+
+        # Things in this set are passed to modules and accessible
+        # in the top-level arguments (e.g. `{ pkgs, lib, inputs, ... }:`).
+        specialArgs = {
+          inherit inputs;
+        };
+
+        hm-nixos-as-super = { config, ... }: {
+          # Submodules have merge semantics, making it possible to amend
+          # the `home-manager.users` submodule for additional functionality.
+          options.home-manager.users = lib.mkOption {
+            type = lib.types.attrsOf (lib.types.submoduleWith {
+              modules = [ ];
+              # Makes specialArgs available to Home Manager modules as well.
+              specialArgs = specialArgs // {
+                # Allow accessing the parent NixOS configuration.
+                super = config;
+              };
+            });
+          };
+        };
+
+        modules = [
+          { 
+             nixpkgs.overlays = [ inputs.emacs.overlay ];
+             system.configurationRevision = 
+               if self ? rev
+               then self.rev
+               else throw "Refusing to build from a dirty Git tree!";
+          }
+
+          inputs.hardware.nixosModules.lenovo-thinkpad-x220
+          (import ./hosts/thinkpad-x220)
+
+          inputs.home.nixosModules.home-manager
+          (import ./modules/home.nix)
+
+          inputs.nixpkgs.nixosModules.notDetected
+          hm-nixos-as-super
+        ];
+      in lib.nixosSystem { inherit system modules specialArgs; };
     };
-    nixos = inputs.self.nixosConfigurations.nixos.config.system.build.toplevel;
   };
 }