(defer-yield on-pause on-resume) on-pause: any form on-resume: any form
Defers evaluation until a coroutine is paused and/or resumed.
This special form is a complement to
defer. It evaluates one form every time
it goes out of scope because its coroutine was paused, and evaluates another form every
time it comes back into scope because its coroutine was resumed. (Under those
defer form would not be evaluated.)
defer-yield appears outside of a coroutine, it's a silent no-op.