[lpghatguy]

This is incredibly funny and also brilliant: toss/return is an implementation of algebraic effects!

[gpderetta]

call/cc as the only control flow primitive!

[firstlink]

Algebraic effects use delimited continuations (and this appears to match toss/return). Call/cc captures an undelimited continuation. Totally different.

[dirkt]

Also called "continuation monad", which can be proven to be universal.

So, no surprise.