Support callback/observable style API

As per discussions on Discord, it’d be nice to have a callback/observable style API in meros, for cases where using async iterators etc aren’t possible/desirable. Adding a ticket here to track that.

[zth]

Kind of a separate question - have you considered running non-multipart responses through the same API (just that it’d complete directly after a single part)?

That way one could always do subscribe etc in the observable case, and not worry about whether it is a multipart response or not. One could set up one flow that handles them both.

[zth]

I think that looks great! How would errors/completion be handled?

Re why: this particular project targets old(er) TVs, where async iterators aren’t supported, and where the code base itself has certain restrictions on the JS features it uses overall (even transpiled).

But outside of that, I think an observable/callback based API is more approachable in general, especially to some segments of developers. That’s obviously my highly personal opinion, you’ll of course need to decide whether you think those things are worth implementing and supporting that alternative API 😄