Re: 64-bit unsigned integer?

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On 28/02/2018 11:39, J-P. Rosen wrote:
> Le 28/02/2018 à 11:17, Paul Rubin a écrit :
>> Having an unsigned int type that 1) uses all the bits in the machine
>> word, and 2) errors on overflow, plus a separd Word type that wraps
>> around, seems like the right way to do things.  Oh well.
> That would certainly raise many issues. For example, this type would
> certainly not have a unary minus... and if a negative result is found in
> intermediate calculations, C_E should be raised.
> 
> Totally different arithmetic => a new kind of integer type. Just for the
> sake of a single (albeit important sometimes) use case.

On top of that, I think that overflow check in this and similar cases is 
not a problem but a solution born out of necessity. Actually, required 
is absence of overflows, not catching them at run-time. Thus a 
combination of SPARK and a 64-bit modular type could be a far better 
approach.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de