Overall this article is accurate and well-researched. Thanks to Daroc Alden for due diligence. Here are a couple of minor corrections:

> When using an Io.Threaded instance, the async() function doesn't actually do anything asynchronously — it just runs the provided function right away.

While this is a legal implementation strategy, this is not what std.Io.Threaded does. By default, it will use a configurably sized thread pool to dispatch async tasks. It can, however, be statically initialized with init_single_threaded in which case it does have the behavior described in the article.

The only other issue I spotted is:

> For that use case, the Io interface provides a separate function, asyncConcurrent() that explicitly asks for the provided function to be run in parallel.

There was a brief moment where we had asyncConcurrent() but it has since been renamed more simply to concurrent().