OT (partially): about promotion of integers

[eles]

> There's a lot to be discussed on the issue. A few quick 
> thoughts:
>
> * 32-bit integers are a sweet spot for CPU architectures. 
> There's rarely a provision for 16- or 8-bit operations; the 
> action is at 32- or 64-bit.

Speed can be still optimized by the compiler, behind the scenes. 
The approach does not asks the compiler to promote everything to 
widest-integral, but to do the job "as if". Currently, the choice 
of int-C as the fastest-integral instead of widest-integral move 
the burden from the compiler to the user.

> * Then, although most 64-bit operations are as fast as 32-bit 
> ones, transporting operands takes twice as much internal bus 
> real estate and sometimes twice as much core real estate (i.e. 
> there are units that do either two 32-bit ops or one 64-bit op).
>
> * The whole reserving a bit and halving the range means extra 
> costs of operating with a basic type.

Yes, there is a cost. But, as always, there is a balance between 
advantages and drawbacks. What is favourable? Simplicity of 
promotion or a supplimentary bit?

Besides, at the end of the day, a half-approach would be to have 
a widest-signed-integral and a widest-unsigned-integral type and 
only play with those two.

Eles