{
  description = "Personal XMonad configuration.";

  inputs = {
    haskell-nix.url = "github:input-output-hk/haskell.nix";
    nixpkgs.follows = "haskell-nix/nixpkgs-unstable";
    flake-utils.follows = "haskell-nix/flake-utils";
  };

  outputs = { nixpkgs, flake-utils, haskell-nix, ... }:
    flake-utils.lib.eachDefaultSystem (system:
      let
        pkgs = import nixpkgs {
          inherit system overlays;
          inherit (haskell-nix) config;
        };
        overlays = [
          haskell-nix.overlay
          (final: _: {
            xmonad-ng = final.haskell-nix.project' {
              src = ./.;

              compiler-nix-name = "ghc8107";

              shell = {
                tools = {
                  brittany = { };
                  cabal = { };
                  haskell-language-server = { };
                  hlint = { };
                };

                buildInputs = with pkgs; [ nixfmt ];
              };
            };
          })
        ];

        flake = pkgs.xmonad-ng.flake { };
      in flake // {
        defaultPackage = flake.packages."xmonad-ng:exe:xmonad-ng";
      });
}