> Known constraints like guaranteed to terminate is useful.
"Guaranteed to terminate" actually means "guaranteed to terminate in finite but possibly arbitrarily large time" which is really not a useful property.
There's no practical difference between a filter that might take 1 billion years to run and one that might take more than a billion years.
Yes but when you combine it with the other guarantees on performance.
https://github.com/google/cel-spec/blob/master/doc/langdef.m...
And your service puts an upper bound on input size and cel expression size. (True for all practical applications.)
You can actually get a guarantee tha t you can't construct a billion year expression. And even guarantee that all expressions will evaluate in let's say 60 secs.
Turing completeness by itself does not guarantee this but it is a necessary prerequisite for these guarantees.