How would you create a dependency key for something that has an async initializer?

[BrentMifsud]

For example, CLMonitor:

[stephencelis]

Generally you should consider dependency values as static interfaces, so the key could be of a sendable closure instead:

static var liveValue: @Sendable () async -> CLMonitor = {
  await CLMonitor("my-location-monitor)
}

Or if you need a long-living monitor, you could wrap it in an actor:

actor Monitor {
  private var _rawValue: CLMonitor?

  var rawValue: CLMonitor {
    get async {
      guard let _rawValue else {
        let rawValue = await CLMonitor("my-location-monitor")
        _rawValue = rawValue
        return rawValue
      }
      return _rawValue
    }
  }
}

// ...
static var liveValue: Monitor { Monitor() }

More work would need to be done to make things testable, though. Check out Designing dependencies for more info.