Elf scripsit:
they'll all be call-with-values on the inside, or the equivalent thereof.
Almost. When you have one of these restricted macros, you can be quite
sure that the producer and consumer lambdas don't escape the construct.
That allows certain optimizations that would otherwise be difficult or
(in the presence of call/cc) impossible, like not actually having them
(as I said, having the producer put its n returned values into n registers
where the consumer code (the body) expects to find them.