That's exactly what I've been doing (minus the END DEF, which I believe is wrong). I couldn't even get the doc's examples to work. I did manage to get them working with the DEF FUNC ARG1,ARG2,... OUT X,Y,... definition but it forces me to write the return value to a variable.

I made that. If you have any experience in programming it should be pretty easy to use. Even if you don't, BASIC is an easy language to learn.

A Touhou fangame. Gonna have fun with bullet patterns!