{
  perSystem =
    { pkgs, ... }:
    let
      hp = pkgs.haskellPackages;
      zookeeper = hp.callCabal2nix "zookeeper" ./. { };
    in
    {
      devShells.zookeeper = hp.shellFor {
        nativeBuildInputs = builtins.attrValues {
          inherit (pkgs)
            nil
            stylish-haskell
            ;
          inherit (hp)
            cabal-install
            cabal-gild
            haskell-language-server
            ;
        };
        packages = _: [ zookeeper ];
      };
      packages = { inherit zookeeper; };
    };
}