Use flakes (#6)

flake.nix

@@ -0,0 +1,46 @@
+{
+  description = "Patrick's Darwin Nix setup";
+
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixpkgs-unstable";
+    home-manager = {
+      url = "github:nix-community/home-manager";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+    darwin = {
+      url = "github:lnl7/nix-darwin/master";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+    emacs = {
+      url = "github:nix-community/emacs-overlay";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+  };
+
+  outputs = { self, darwin, emacs, nixpkgs, home-manager, ... }@inputs:
+    let system = "aarch64-darwin"; in
+    let config = {
+      allowUnfreePredicate = pkg: builtins.elem (nixpkgs.lib.getName pkg) [
+        "vscode"
+      ];
+    }; in
+    let overlays = [ emacs.overlay ] ++ import ./overlays.nix; in
+    let pkgs = (import nixpkgs { inherit system config overlays; }); in
+    {
+      darwinConfigurations = {
+        nixpkgs = pkgs;
+        patrick = darwin.lib.darwinSystem {
+          system = system;
+          modules = [
+            ./darwin-configuration.nix
+            home-manager.darwinModules.home-manager
+            {
+              home-manager.useGlobalPkgs = true;
+              home-manager.useUserPackages = true;
+              home-manager.users.Patrick = import ./home.nix { nixpkgs = pkgs; };
+            }
+          ];
+        };
+      };
+    };
+}