Spec#, nullables and more

[Walter Bright]

bearophile wrote:
> Walter:
> 
>> Any type having an unexpected value in it is a very common bug. They often
>> go unnoticed, though, because they don't generate a seg fault. The bug is
>> still there, though.
>> 
>> So no, I don't agree it is a special case.
> 
> Then to D3, beside nonnull types, we may also add ranged integers (as integer
> subtypes or subtypes of other ranges). With both those things you have
> probably covered a good percentage of what you call "unxpected value" bugs.


Adding ranged integer types increases the coverage from 1% to 2% of the cases. 
(Pulling random numbers out of the ether, but still, I think the point is valid.)