--TEST-- yield can be used without a value --FILE-- <?php function recv() { while (true) { var_dump(yield); } } $receiver = recv(); var_dump($receiver->current()); $receiver->send(1); var_dump($receiver->current()); $receiver->send(2); var_dump($receiver->current()); $receiver->send(3); ?> --EXPECT-- NULL int(1) NULL int(2) NULL int(3)