How would one implement publish subscribe / concur...

# arrow

[Johan Basson]

How would one implement publish subscribe / concurrency in a functional (arrow) way?

[Satyam Agarwal]

+

[simon.vergauwen]

You can build purely functional actors with Queue, Promise and recursion.

[simon.vergauwen]

An easier way of implementing it would be using Streams but those are something I’ll work on in 2020.

[simon.vergauwen]

https://github.com/vlovgr/actors-cats-effect-fs2/blob/master/src/main/scala/app/actors.scala

[raulraja]

For other higher level concurrent stuff https://arrow-kt.io/docs/effects/fx/async/

[simon.vergauwen]

I’ve ported this example in the passed and everything you need is available in Arrow Fx.

[Tesserakt]

Very interesting example with actors. In my project I use Generative typeclass. This is something like an observable - asynchronously creates a stream. https://github.com/ITesserakt/diskordin/blob/master/src/main/kotlin/org/tesserakt/diskordin/util/typeclass/Generative.kt
https://github.com/ITesserakt/diskordin/blob/master/src/main/kotlin/org/tesserakt/diskordin/impl/util/typeclass/GenerativeOps.kt

[Johan Basson]

Found this in Arrows documentation: https://arrow-kt.io/docs/effects/async/

[Johan Basson]

If I understand correct, this might do it:

[Johan Basson]

IO.async().run {
// In current thread
invoke(CommonPool) {
// In CommonPool
requestSync(createUserFromId(123))
}
}

[Tesserakt]

For this use continueOn(CommonPool).bind() or

effect {
    withContext(CommonPool) {
        //...
   }
}.bind()

[Johan Basson]

Thanks!