Higher-ranked projections (send bound problem, part 4)

from blog baby steps, | ↗ original
I recently posted a draft of an RFC about Return Type Notation to the async working group Zulip stream. In response, Josh Triplett reached out to me to raise some concerns. Talking to him gave rise to a 3rd idea for how to resolve the send bound problem. I still prefer RTN, but I think this idea is interesting and worth elaborating. I call it...