{
  description = "Personal XMonad configuration.";

  inputs = {
    nixpkgs = {
      type = "github";
      owner = "NixOS";
      repo = "nixpkgs";
      ref = "nixpkgs-unstable";
    };

    flake-utils = {
      type = "github";
      owner = "numtide";
      repo = "flake-utils";
      ref = "master";
      inputs.nixpkgs.follows = "nixpkgs";
    };

    flake-compat = {
      type = "github";
      owner = "edolstra";
      repo = "flake-compat";
      ref = "master";
      flake = false;
    };

    pre-commit-hooks = {
      type = "github";
      owner = "cachix";
      repo = "pre-commit-hooks.nix";
      ref = "master";
      inputs = {
        nixpkgs.follows = "nixpkgs";
        flake-utils.follows = "flake-utils";
      };
    };
  };

  outputs = inputs:
    with inputs;
    let name = "xmonad-ng";
    in flake-utils.lib.eachDefaultSystem (system:
      let
        pkgs = nixpkgs.legacyPackages.${system};

        project = returnShellEnv:
          pkgs.haskellPackages.developPackage {
            inherit name returnShellEnv;
            root = ./.;
            overrides = self: _:
              with pkgs.haskell.lib;
              let
                mkPackage = packageName:
                  dontCheck (self.callHackage packageName "0.17.0" { });
              in {
                xmonad = mkPackage "xmonad";
                xmonad-contrib = mkPackage "xmonad-contrib";
              };
            modifier = drv:
              pkgs.haskell.lib.addBuildTools drv (with pkgs.haskellPackages; [
                brittany
                cabal-install
                haskell-language-server
                hlint
                hpack
                stack
              ]);
          };
      in {
        defaultPackage = project false;

        checks.preCommit = pre-commit-hooks.lib.${system}.run {
          src = ./.;
          hooks = {
            nix-linter.enable = true;
            nixfmt.enable = true;
            hpack.enable = true;
            hlint.enable = true;
            yamllint.enable = true;
            brittany.enable = true;
            shellcheck.enable = true;
            shfmt = {
              enable = true;
              name = "shfmt";
              entry = "${pkgs.shfmt}/bin/shfmt -s -w";
              types = [ "shell" ];
            };
            prettier = {
              enable = true;
              types = [ ];
              files = "\\.((yaml)|\\d)$";
            };
          };
        };

        shells = {
          dev = project true;
          commit = pkgs.mkShell {
            inherit (self.checks.${system}.preCommit) shellHook;
          };
        };

        devShell = self.shells.${system}.dev;
      }) // {
        overlay = _: _: { ${name} = self.defaultPackage; };
      };
}