There isn't anything. Dave thomas proposed a better way of organizing genservers, but I can't get behind it because his implementation is too magical and clever, but his idea for what the api should look like in the big picture is reasonable... I'm also generally in favor having everyone speak the same idioms, so it would take a very good implementation to get me off of genserver.
That said you shouldn't write genservers if you can help it. Using the frameworks genservers Is the best choice, Task is a better choice for most cases.