Glyn: Type-safe PubSub and Registry for Gleam actors, built on Syn

[unkempt python]

My first gleam library! https://github.com/mbuhot/glyn

It's a wrapper over syn (https://github.com/ostinelli/syn) that integrates with Gleam's typed actor system with Subjects and Selectors.

Creating this finally made the typed actor system to click for me, I had to re-wire my brain after years of untyped messaging in Elixir 🙂
Being able to select_map multiple Subjects into a single Actor mailbox feels like a new super power.

My next goal is to use this to build a distributed chat app with websockets in Wisp.

[grave wagon]

Oooh useful!!

[limber raft]

👀

[grave wagon]

Do you know how the groups scale? pg for example is better with many small groups, or larger groups with infrequent leaving, as member removal uses lists:remove

The start function doesn’t return a Started and the supervised function is missing. Would be great to have those so it can be used in real programs with supervision

What’s the glyn module for? It defines one type and but I can’t see where it’s ised

Oh it’s used in the constructor for the pubsub registry. This isn’t type safe!

It looks like you could get rid of that argument though and it would become type safe?

[unkempt python]

Making it type safe in a distributed setting might be impossible?, but the MessageType(message) was an attempt to minimize the chance of misuse.
Essentially I need some tag to use for the subject that corresponds to the message type that will be published.
Very open to suggestions 🙏

[unkempt python]

Could you provide some more details on the supervision?
If Glyn is a library that doesn't directly supervise any processes, but has a dependency on Syn which is an OTP application with supervision tree, will an app that depends on Glyn automatically start Syn?

[grave wagon]

Oh so it uses some implicit global state instead of managing processes directly

[grave wagon]

It’s not possible to be type safe in a distributed setting but this API makes it unsafe with a single node