Comment by bulbar
1 month ago
UB is about edge cases that a compiler should not be enforced to check against and an occurrence is always a bug. You don't necessarily need a precise description of the actual faulty behavior.
1 month ago
UB is about edge cases that a compiler should not be enforced to check against and an occurrence is always a bug. You don't necessarily need a precise description of the actual faulty behavior.
Right. The language has well-formed expressions with no defined meaning in terms of machine instructions. My claim is that this is a reduction in precision compared to assembly language.
Grandparent said:
> The single best feature of any programming language is that it is precise.
C overtook a more precise language family because it has features other than precision that people cared about. Perhaps a better tradeoff of expressiveness and readability with precision.
Grandparent could be correct, and precision is the best feature of C, despite being less precise than ASM. And its better expressiveness nets out to a better overall programmer experience. I just wanted to point out that precision is something we do trade away for other things we want.
I don't completely follow the analogy, but I do follow the argument. High precision regarding the requirements often is not needed and that's exactly where LLMs shine.
That's also where engineers come into play. They (and often only they) can judge how much precision is needed depending on the part of the system they are working on.
Could you please explain why you feel that having UB makes C less precise than asm?
To me, the notion of precision isn't in any way related to whether any given statement is sound. It's about the behavior of the language for sound programs.
There are syntactically well-formed C programs that are not sound programs because their behavior is undefined. Or, rephrasing: a subset of all parseable C programs contain 'do whatever, I dunno'. I interpret this as a lack of precision.
One could take the position that specifying precisely 'do whatever, I dunno' counts as perfectly precise. But then a language that was entirely UB would count as precise, which would be an odd position to hold, since you can't specify any behavior at all with it.
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