Allow creation of system-specific config files

flake.nix

@@ -7,7 +7,9 @@
 
     outputs = { self, nixpkgs }: 
     let
-        system = import ./system.nix;
+        system = import ./lib/system.nix {
+            inherit nixpkgs;
+        };
     in {
         nixosConfigurations.manu-surface = system "manu-surface" {};
     };

lib/system.nix

@@ -1,12 +1,18 @@
+{ nixpkgs }:
     name :
         { dualBoot ? false } :
-        nixpkgs.lib.nixosSystem {
+            let
+                lib = nixpkgs.lib;
+            in
+                lib.nixosSystem {
                     system = "x86_64-linux";
                     modules = [
+                        (lib.optional (builtins.pathExists ../machines/${name}.nix) ../machines/${name}.nix)
+                        (
                             { config, pkgs, ... }: {
                                 imports = [
                                     ../hardware-configuration.nix
                                 ];
-                    }
+                            })
                     ];
                 }