On Haskell, yes, you can just work off a thread and write shared buffers. But you are better off using STM or Async (these are a bit like futures), which compose, and you can write pipelines out of them.
Not sure what you mean by "actor frameworks don't compose"?
Maybe composition for compositions' sake isn't that important?
But if you have the choice, composability always seems much nicer to me and stops me wanting to tear my hair out.
In the sense of being failure domains, OTP "actors", or processes, ARE composable. With very little boilerplate, that is built in as primitive BIFs in the standard library, I can bundle failure domains together and orchestrate them using links, monitors, and supervision strategies, with the ultimate failure domain being a single erlang VM operating inside a cluster of erlang VMs, all supported without third party libraries as a part of the way of doing things.
Then the idea of adding a supervising and observability was a natural addition to these systems.
That said, I think OTP is a great tool for modeling failure domains and I think it does a great job.
Definitely. I was about to ask "but when did you actually need to compose actors and how does that even make sense?" -- and while I am sure there are people who would find a scenario I feel that would still be tarrying on minutiae.
Obviously the actor model is not a panacea. But for my commercial work Elixir -- and thus Erlang's OTP -- has been a true blessing. There aren't many commercial scenarios where OTP is a very poor fit. They do exist but I'd dare saying they are no more than 10-15% of everything you can stumble upon out there.
It's quite sad how fiercely the average HN audience is attacking people who are trying to show an alternative way of doing things.