[alexisread]

Interestingly Wat implements a callstack in a userland VM, to implement it's delimited continuations. Ergonomically it would be good to implement algebraic effects on top, but the basis is there, along with demos of exception handling, branching, fibres etc.

https://github.com/manuel/wat-js

Obviously with forths the callstack is already in userland to implement these things, might be a bit brain-bending in forth.