[eaurouge]

Nurseries sound similar to run-till-completion schedulers [0].

> IMO the urge to use both the actor model (and its relative, CSP) in non-distributed systems solely in order to achieve concurrency has been a massive boondoggle

Can't you model any concurrent non-distributed system as a concurrent distributed system?

0. https://en.wikipedia.org/wiki/Run-to-completion_scheduling

[kibwen]

> Can't you model any concurrent non-distributed system as a concurrent distributed system?

Yes, in the same way that you can give up `for` loops and `while` loops and `if` statements and `switch` statements and instead write them all with `goto`, but you don't do this, and anyone advising you to do this would be written off as insane. The entire thrust of this thread is that you can have a more reliable system that is easier to reason about if you use specific constructs that each have less power, and non-distributed systems have the option to do this. Unstructured concurrency should be reserved exclusively for contexts where structured concurrency is impossible, which is what the actor model is for.

[eaurouge]

The point I was trying to make is that you can apply the actor model to any system of isolated processes. Whether the isolated processes live on a distributed system of networked computers or on the same computer is an implementation detail. The critical issue is that each actor should own and mutate its own state. Whether all actors run on the same thread or on separate threads is also an implementation detail. For instance, AtomVM is a lightweight implementation of the Beam (actor model) that runs on microcontrollers [0].

> The entire thrust of this thread is that you can have a more reliable system that is easier to reason about if you use specific constructs that each have less power

Easier to reason about, sure, fine. Your earlier comment claims the actor model is a dead end in non-distributed systems.

> Unstructured concurrency should be reserved exclusively for contexts where structured concurrency is impossible, which is what the actor model is for.

Results from my quick search on structured/unstructured concurrency were all references to Swift. Is this a Swift thing? In any case, the issue appears to be more about managing tasks that don't require a preemptive scheduler. As I see it, that issue appears orthogonal to distributed/non-distributed systems.

0. https://atomvm.org/

[k_g_b_]

Structured concurrency is also a Kotlin thing https://kotlinlang.org/docs/coroutines-basics.html#coroutine... and a Python thing https://vorpus.org/blog/notes-on-structured-concurrency-or-g... and before that it was a C thing https://sustrik.github.io/250bpm/blog:71/

[kibwen]

> Easier to reason about, sure, fine. Your earlier comment claims the actor model is a dead end in non-distributed systems.

If you have two ways of structuring something, and the worse way is so predominant that it obscures even the existence of the better way, that's a dead end in my book. In the pre-structured-programming days when people had to fight tooth and nail to get people to acknowledge the value of `if` and `while` over `goto`, we would have also called `goto` a dead end; it's plain to see that we would be in a worse place today if the structured programming advocates had not managed to convince everyone of its superiority.

> Results from my quick search on structured/unstructured concurrency were all references to Swift. Is this a Swift thing?

I have no idea whether Swift supports it, but no, it's not a Swift thing any more than `while` and `if` are a Python thing. I highly, highly encourage people to read the linked blog post, it will be the best use of your time today.

[eaurouge]

I read the article you referenced. It's based on, and described wrt, Python's `async with` (so quite a few layers of abstraction), so I can't say with certainty how it's implemented. But, as I noted earlier, it isn't really that different from a run-till-completion task scheduler and is not particularly novel or interesting, imo.

[janderland]

Don’t Erlang/Elixir model all concurrency as actors, to some level of success. I was under the impression that it allows for quite a bit of deployment flexibility. Actors are addressed in the same way whether they’re on the same machine or not.

[felixgallo]

yes, to huge levels of success. It's not clear what kibwen is going on about, but local + remote actor concurrency transparency, while not without its complications, comes with massive development and deployment wins.

[ahoka]

You can certainly make any simple problem complicated enough to need a complex solution. But that’s just bad engineering.