On Tue, Jun 2, 2020 at 2:58 PM Paul Winalski <paul.winalski@gmail.com>
wrote:

> I think that's a very good question.  It's analogous to
> record-oriented I/O vs. byte stream I/O.  It's easy to build
> record-oriented I/O on top of a byte stream, but it's a real bear to
> do it the other way around.  Similarly, it's easy to build synchronous
> I/O on top of asynchronous I/O but the reverse ends up looking contrived.
>
Which was exactly the point I tried to make in the POSIX.4 discussions, but
it does take more work in the basic housekeeping and you need a way to
handle events and completions that are priority based, queued, and a few
other details.   As Doug said, they stayed away from some features (like
messaging).   async I/O was one of them.

But as I said, Ken, Dennis and the rest of the crew did an amazing job with
very little.