Interesting, interesting. It would take me a few hours of playing with this mechanism to know what I think of it as a primitive, but for me this solution is relevant to a problem I really have so I might take a look. Right now I just write methods that sometimes return a promise and sometimes don't.

> except you can optionally return a teardown function, for example:

Kind of reminds me of https://doc.rust-lang.org/rust-by-example/trait/drop.html

Do you want monads? Because this is how you get monads.

Interesting stuff!

The two separate failure channels turn me off. Is this practical or does it introduce unwanted complexity in most cases?

Also wondering what are the Signals that are mentioned.