What is Isolated<T> used for?

[iwt-sebastian-boldt]

Hey Guys 😉 ,

I stumbled across something I can not fully grasp.
Inside the APIClient Dependency e.g you create an actor to synchronize access to a shared resource.
This actor has some non-isolated properties -> I assume because access to these properties does not need to be isolated because they are declared as let anyways.
But then you wrap the Type related to this nonIsolated property into something called Isolated.
Is there any explanation for this somewhere? I would really appreciate any info about it 🙇

nonisolated let baseUrl: Isolated<URL>

[stephencelis]

Hi @iwt-sebastian-boldt! This type is similar to our ActorIsolated type, which we use in the Composable Architecture. It uses a lock under the hood, instead, though, to make a value concurrency-friendly (and sendable) without requiring the overhead of an actor.

We can then use nonisolated on the actor to allow for synchronous access without needing to await.

We're looking into incorporating this type into our library ecosystem in the future, but wanted to give it some use in isowords first 😄