Comment by recursive

In what way was the language async? It has no threads outside workers, which have strict limits regarding data sharing. You would see a lot of code that registers callbacks as event handlers, but I don't think that makes the language async. That's just the nature of event handlers. They are invoked later, when the event happens.

In a way, the lack of threading allowed `async` to be implemented without gotchas. In languages with first-class thread support, `async` implementations can run into thread issues. (Will the continuation run on the same thread? Does the code care?)