Switched to using flake-utils

This reducies the number of things that I will need at sometime in the
theortical future, by doing more work now.

flake.lock

@@ -1,5 +1,35 @@
 {
   "nodes": {
+    "emacs-overlay": {
+      "locked": {
+        "lastModified": 1639416884,
+        "narHash": "sha256-ucI8w/JcQQzEbppfPBK7HPfsy3HRi5hy2FoksuvkPCc=",
+        "owner": "nix-community",
+        "repo": "emacs-overlay",
+        "rev": "9516033899da467b8fcee6536a61ea66ebd0c4fa",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-community",
+        "repo": "emacs-overlay",
+        "type": "github"
+      }
+    },
+    "flake-utils": {
+      "locked": {
+        "lastModified": 1629481132,
+        "narHash": "sha256-JHgasjPR0/J1J3DRm4KxM4zTyAj4IOJY8vIl75v/kPI=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "997f7efcb746a9c140ce1f13c72263189225f482",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
     "home-manager": {
       "inputs": {
         "nixpkgs": [
@@ -69,10 +99,31 @@
     },
     "root": {
       "inputs": {
+        "emacs-overlay": "emacs-overlay",
         "home-manager": "home-manager",
         "nixos-hardware": "nixos-hardware",
         "nixpkgs": "nixpkgs",
-        "nur": "nur"
+        "nur": "nur",
+        "utils": "utils"
+      }
+    },
+    "utils": {
+      "inputs": {
+        "flake-utils": "flake-utils"
+      },
+      "locked": {
+        "lastModified": 1632420560,
+        "narHash": "sha256-8Tsa4Hp/CHCA6J8/E7EODhp75z5N1NBhFiOb3lBv/tI=",
+        "owner": "gytis-ivaskevicius",
+        "repo": "flake-utils-plus",
+        "rev": "4b1bcafcfcd78bd36ceabfe3872822ba5c7fcbe8",
+        "type": "github"
+      },
+      "original": {
+        "owner": "gytis-ivaskevicius",
+        "ref": "v1.3.0",
+        "repo": "flake-utils-plus",
+        "type": "github"
       }
     }
   },

flake.nix

@@ -3,6 +3,7 @@
 
   inputs = {
     nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+    utils.url = "github:gytis-ivaskevicius/flake-utils-plus/v1.3.0";
 
     home-manager = {
       url = "github:nix-community/home-manager";
@@ -18,35 +19,46 @@
       url = "github:NixOS/nixos-hardware/master";
       inputs.nixpkgs.follows = "nixpkgs";
     };
+
+    emacs-overlay = {
+      url = "github:nix-community/emacs-overlay";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
   };
 
-  # All outputs for the system (configs)
+  outputs = inputs@{ self, utils, nixpkgs, nixos-hardware, nur, home-manager
-  outputs = { home-manager, nixpkgs, nur, nixos-hardware, ... }:
+    , emacs-overlay, ... }:
-    let
+    utils.lib.mkFlake {
-      system = "x86_64-linux";
+      hosts = {
-      pkgs = import nixpkgs {
+        nil.modules = [
-        inherit system;
+          nixos-hardware.nixosModules.lenovo-thinkpad-t14-amd-gen1
-        config = { allowUnfree = true; };
+          ./hosts/nil.nix
+        ];
       };
-      lib = nixpkgs.lib;
-    in {
-      nixosConfigurations = {
-        # Config is based on hostname
-        nil = lib.nixosSystem {
-          system = "x86_64-linux";
-          modules = [
-            nixos-hardware.nixosModules.lenovo-thinkpad-t14-amd-gen1
-            ./hosts/nil.nix
-            home-manager.nixosModules.home-manager
-            {
-              home-manager.useGlobalPkgs = true;
-              home-manager.useUserPackages = true;
-              home-manager.users.james = import ./home.nix;
-            }
-            { nixpkgs.overlays = [ nur.overlay ]; }
-          ];
-        };
 
+      # Shared logic below.
+      inherit self inputs;
+      supportedSystems = [ "x86_64-linux" ];
+      channels.nixpkgs = {
+        input = nixpkgs;
+        overlaysBuilder = channels: [ ];
       };
+      channelsConfig = { allowUnfree = true; };
+      sharedOverlays = [ nur.overlay emacs-overlay.overlay ];
+      hostDefaults = {
+        modules = [
+          nixos-hardware.nixosModules.lenovo-thinkpad-t14-amd-gen1
+          ./hosts/nil.nix
+          home-manager.nixosModules.home-manager
+          {
+            home-manager.useGlobalPkgs = true;
+            home-manager.useUserPackages = true;
+            home-manager.users.james = import ./home.nix;
+          }
+          { nixpkgs.overlays = [ nur.overlay ]; }
+        ];
+        system = "x86_64-linux";
+      };
+
     };
 }