{ config, lib, pkgs, ... }: { imports = [ ]; options.me = { postgresql_client.enable = lib.mkOption { type = lib.types.bool; default = false; example = true; description = "Whether we want to install postgresql_client."; }; }; config = lib.mkIf config.me.postgresql_client.enable { environment.systemPackages = with pkgs; [ pgformatter ]; }; }