boxed VS trio

I was happy when Promise became available, but in retrospect I'd wish we would have skipped ahead and gotten Observable (e.g: https://rxjs.dev/) instead to enable more powerful functionality and composition etc.

In Typescript dealing with rejection is also painful since rejection reasons can't be guaranteed to be Error even when you always take care of that. And it can't help you guarantee that you're handling all types of errors thrown. For that purpose I'm thinking of using https://github.com/supermacro/neverthrow#readme or https://swan-io.github.io/boxed.

Agree that try/catch is verbose and not terribly ergonomic, but my solution has been to treat errors as values rather than exceptions, by default. It's much less painful to achieve this if you use a library with an implementation of a Result type, which I admin is a bit of a painful workaround, but worth it. I've recently been using: https://github.com/swan-io/boxed.

By far the greatest benefit is being able to sanely implement a type-safe API. To me, it is utter madness throwing custom extensions of the Error class arbitrarily deep in the call-stack, and then having a catch handler somewhere up the top hoping that each error case is matched and correctly translated to the intended http response (at least this seems to be a common alternative).

Incidentally, the alternative event loop implementation trio in python does not have "gather", you also need channels, and it's a deliberate design choice - there is some discussion about that in this ticket https://github.com/python-trio/trio/issues/2188

trio – a friendly Python library for async concurrency and I/O

trio. the best code, the best documentation, awesome community.

I'll +1 the Trio shoutout [1], but it's worth emphasizing that the core concept of Trio (nurseries) now exists in the stdlib in the form of task groups [2]. The article mentions this very briefly, but it's easy to miss, and I wouldn't describe it as a solution to this bug, anyways. Rather, it's more of a different way of writing multitasking code, which happens to make this class of bug impossible.

[1] https://github.com/python-trio/trio

[2] https://docs.python.org/3/library/asyncio-task.html#task-gro...

It's similar to manual memory management.

Structured concurrency is one approach to solving this problem. In a structured concurrency a promise would not go out of scope unhandled. Not sure how you would add APIs for it though.

See Python's trio nurseries idea which uses a python context manager.

https://github.com/python-trio/trio

I'm working on a syntax for state machines and it could be used as a DSL for promises. It looks similar to a bash pipeline but it matches predicates similar to prolog.

In theory you could wire up a tree of structured concurrency with this DSL.

https://github.com/samsquire/ideas4#558-assign-location-mult...

Not complete - doesn't include Task Groups [1]

In fairness they were only included in asyncio as of Python 3.11, which was released a couple of weeks ago.

These were an idea originally from Trio [2] where they're called "nurseries" instead of "task groups". My view is that you're better off using Trio, or at least anyio [3] which gives a Trio-like interface to asyncio. One particularly nice thing about Trio (and anyio) is that there's no way to spawn background tasks except to use task groups i.e. there's no analogue of asyncio's create_task() function. That is good because it guarantees that no task is ever left accidentally running in the background and no exception left silently uncaught.

[1] https://docs.python.org/3/library/asyncio-task.html#task-gro...

[2] https://github.com/python-trio/trio

[3] https://anyio.readthedocs.io/en/latest/