modules/nilla: flake compatibility module

modules/nilla/default.nix

@@ -4,5 +4,6 @@
     ./services.nix
     ./configurations.nix
     ./modules.nix
+    ./flake.nix
   ];
 }

modules/nilla/flake.nix

@@ -0,0 +1,31 @@
+{ lib, config }:
+let
+  systems = [
+    "x86_64-linux"
+    "aarch64-linux"
+    "aarch64-darwin"
+  ];
+  transpose =
+    attrs: lib.attrs.generate systems (system: builtins.mapAttrs (_: pkg: pkg.result.${system}) attrs);
+in
+{
+  options.flake = lib.options.create {
+    type = lib.types.attrs.of lib.types.raw;
+  };
+
+  config.flake = {
+    inherit (config)
+      nixosModules
+      darwinModules
+      homeModules
+      nixosConfigurations
+      darwinConfigurations
+      homeConfigurations
+      ;
+
+    devShells = transpose config.shells;
+    packages = transpose config.packages;
+
+    formatter = config.packages.formatter.result;
+  };
+}