09.10.2012 3:12, Lorenzo Caminiti wrote:
Because if the primary role of axioms is to state concept's semantics then I'd expect them to be used to enforce concept's semantics (with some type of compile-time checking) instead than using them for some optimization that BTW is going to be compiler-specific.
I don't see big problems with some degree of optimizations which are done by one compiler but not by another. We already have copy-elision which works better on some compilers than on others.
You standardize axioms but how would you standardize the optimization that a compilers will generate based on them? If such optimization cannot be standardized (I don't think it can) and if that is the main reason for axioms, why are axioms standardized?
I agree, and I wrote earlier, well-defined rules which kind of transformations are allowed based on axioms, should be clearly stated. I don't think it is impossible task, but obviously not easy. P.S. I just have wild idea - what about axioms for function's arguments? i.e. not on types, but on values. Maybe some kind of axiomatic_assert. For instance that can be used to prevent pointers aliasing ("restrict" keyword in C99): void* memcpy( void* dest, const void* src, size_t count ) { axiomatic_assert( do_not_overlap(dest,src,count) ); // ... } Best Regards, Evgeny