{ config, lib, pkgs, ... }: with lib; let cfg = config.services.xserver.windowManager.berry; in { ###### interface options = { services.xserver.windowManager.berry.enable = mkEnableOption (lib.mdDoc "berry"); }; ###### implementation config = mkIf cfg.enable { services.xserver.windowManager.session = singleton { name = "berry"; start = '' ${pkgs.berry}/bin/berry & waitPID=$! ''; }; environment.systemPackages = [ pkgs.berry ]; }; }