feat: init scaffolding

flake.nix

@@ -0,0 +1,70 @@
+{
+  inputs = {
+    devshell = {
+      url = "github:numtide/devshell";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+
+    flake-utils.url = "github:numtide/flake-utils";
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+
+    pre-commit-hooks = {
+      url = "github:cachix/pre-commit-hooks.nix";
+      inputs.nixpkgs.follows = "nixpkgs";
+      inputs.flake-utils.follows = "flake-utils";
+    };
+  };
+
+  description = "Extra modules that nobody needs.";
+  outputs = {
+    self,
+    nixpkgs,
+    flake-utils,
+    devshell,
+    pre-commit-hooks,
+    ...
+  }:
+    {
+      nixosModules.extra-modules = import ./modules nixpkgs;
+      nixosModules.default = self.nixosModules.extra-modules;
+    }
+    // flake-utils.lib.eachDefaultSystem (system: rec {
+      pkgs = import nixpkgs {
+        inherit system;
+        overlays = [
+          devshell.overlays.default
+        ];
+      };
+
+      # `nix flake check`
+      checks.pre-commit-hooks = pre-commit-hooks.lib.${system}.run {
+        src = nixpkgs.lib.cleanSource ./.;
+        hooks = {
+          alejandra.enable = true;
+          deadnix.enable = true;
+          statix.enable = true;
+        };
+      };
+
+      # `nix develop`
+      devShells.default = pkgs.devshell.mkShell {
+        name = "extra-modules";
+        commands = with pkgs; [
+          {
+            package = alejandra;
+            help = "Format nix code";
+          }
+          {
+            package = statix;
+            help = "Lint nix code";
+          }
+          {
+            package = deadnix;
+            help = "Find unused expressions in nix code";
+          }
+        ];
+
+        devshell.startup.pre-commit.text = self.checks.${system}.pre-commit-hooks.shellHook;
+      };
+    });
+}