{
  description = "Haskell project";

  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs";
    nix-filter.url = "github:numtide/nix-filter";
    flake-parts.url = "github:hercules-ci/flake-parts";
    systems.url = "github:nix-systems/default";
  };

  outputs =
    inputs@{
      self,
      flake-parts,
      nixpkgs,
      nix-filter,
      ...
    }:
    flake-parts.lib.mkFlake { inherit self inputs; } {
      systems = import inputs.systems;

      flake.overlays.default = final: prev: {
        haskellPackages = prev.haskellPackages.extend (
          hfinal: _hprev: {
            PROJECT =
              let
                src = nix-filter {
                  root = ./.;
                  include = [
                    "src"
                    "app"
                    "package.yaml"
                    "PROJECT.cabal"
                  ];
                };
              in
              hfinal.callCabal2nix "PROJECT" src { };
          }
        );
      };

      perSystem =
        {
          config,
          pkgs,
          system,
          ...
        }:
        {
          _module.args.pkkgs = import nixpkgs {
            inherit system;
            overlays = [ self.overlays.default ];
          };

          packages = rec {
            default = PROJECT;
            inherit (pkgs.haskellPackages) PROJECT;
          };

          devShells.default = pkgs.haskellPackages.shellFor {
            packages = ps: [ ];
            withHoogle = true;
            buildInputs = with pkgs.haskellPackages; [
              cabal-install
              hpack
              hlint
              fast-tags
              pkgs.haskell-language-server
            ];
          };

        };
    };
}