wat-js

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.

Have you looked at Kernel and wat? They use a fundamental operator (vau) to make macros, instead of a special form: https://github.com/manuel/wat-js maru has this vau operator implicitly, rather than explicitly: https://github.com/attila-lendvai/maru

Interestingly Wat (https://github.com/manuel/wat-js) handles Dynamic Variables, which fit well with serialized code, in that the serialization boundary can be better partitioned into variables you need to serialize (locals etc.), and environmental (dynamic) variables which are subject to their runtime env. Wat also happens to have a good concurrency model, and a portable bytecode. Worth looking at in this space.

One evolution of (You're probably aware of re:axisofeval) Kernel is Wat (https://github.com/manuel/wat-js), which implements the Vau operator (hygenic F-exprs), full delimited continuations (as opposed to the usual Shift/reset functionality of most lisp-based langs) and dynamic variables (variables which can break out of the usual lexical ie. compile-time scope and take environmental ie. runtime values). It's quite fast with all of that. The continuations allow you to define promises, threads, channels, exceptions, branching and so on. Thing is, syntatically the continuations are required to carry quite a lot. Algebraic effects layered on top would have a nicer syntax. Similarly, I would suggest that dynamic variables and continuations are more understandable in a forth-like language where the return and data stacks are first class. What'