> to write a NIF that could somehow yield back and then be "continued" later would be a royal pain.

I know... nothing... about the NIF interface, but the way that I would want this to work wouldn't involve NIF resumption at all, but rather for NIFs to be able to put responses back on a channel.

Unfortunately neither quick internet searches nor searching the rustler docs revealed anything about a NIF/channel interface. I'm not sure how feasible it is to pass a channel into a nif and allow it to pass that into some thread and return, nor how good of an idea that would be.