[davidrupp]

I think the inspiration from Simula I is something a lot of folks either don't know about, or maybe they know about it but don't recognize its significance. Objects with encapsulated state that respond to well-defined messages are a useful level of abstraction for writing simulations of the sort Simula was built for. They're just not automatically a particularly wieldy abstraction for systems that aren't specifically about simulation. Some (most?) of that is about the skill of the programmer, imo, not some inherent flaw in the abstraction itself.

P.S.: Thank you for all your contributions to our profession, and for your measured response to these kinds of discussions.

[alankay]

It's out of the context of this thread, but we were quite sure that "simulation-style" systems design would be a much more powerful and comprehensive way to create most things on a computer, and most especially for personal computers.

At Parc, I think we were able to make our point. Around 2014 or so we brought back to life the NoteTaker Smalltalk from 1978, and I used it to make my visual material for a tribute to Ted Nelson. See what you think. https://www.youtube.com/watch?v=AnrlSqtpOkw&t=135s

This system --including everything -- "OS", SDK, Media, GUI, Tools, and the content -- is about 10,000 lines of Smalltalk-78 code sitting on top of about 6K bytes of machine code (the latter was emulated to get the whole system going).

I think what happened is that the early styles of programming, especially "data structures, procedures, imperative munging, etc." were clung to, in part because this was what was taught, and the more design-intensive but also more compact styles developed at Parc seemed very foreign. So when C++, Java, etc. came along the old styles were retained, and classes were relegated to creating abstract data types with getters and setters that could be munged from the outside.

Note that this is also "simulation style programming" but simulating data structures is a very weak approach to design for power and scaling.

I think the idea that all entities could be protected processes (and protected in both directions) that could be used as communicating modules for building systems got both missed and rejected.

Of course, much more can and should be done today more than 40 years after Parc. Massive scaling of every kind of resource requires even stronger systems designs, especially with regard to how resources can be found and offered.