Going back to old school services is doable and safe as long as governments are interested for the security of citizens.
Picat (mentioned by the author) Datalog Mercury XSB
are there more?
They listened to the second part, but not the first.
During summer I had to build around this non-free libraries but their subscription ended when people responsible were in vacations and the project was paused because of design bugs for two months, so they did not plan to renew the license for two months. Still my part had to carry on in the mean time.
I added an open source library as a fallback, even if it was 4x slower. Because of delays the license was renewed 3 months later when design issues were addressed. If they had designed around open source from the start I would have a better time. It was a real pain to replicate the functionality around the open source library. It was not a drop-in, not very far but far enough to cause hard to find bugs, in nasty calculational code. That had a number of bugs already and bad code quality.
My experience.
as long we have to do with a consistent string like theory.
Is my understanding correct?
Use C as a common platform denominator without crazy optimizations (like tcc). If you need performance, specialize, C gives you the tools to call assembly (or use compiler some intrinsic or even inline assembly).
Complex compiler doing crazy optimizations, in my opinion, is not worth it.
https://github.com/mythryl/mythryl