symmetric signed types

[Dominikus Dittes Scherkl]

On Friday, 24 January 2014 at 19:03:59 UTC, Walter Bright wrote:
> On 1/24/2014 2:40 AM, Dominikus Dittes Scherkl wrote:
>> Ah, ok. Of course the small types always become int.
>> But the problem would be the same with
>>
>> long a = long.min;
>> auto b = -a;
>>
>> does this return ulong (which could hold the correct result) 
>> or long (and a
>> wrong result)?
>
> The negation operator does not change the type, and no 
> operation changes the type as the result of particular runtime 
> operand values.
So, was Andrei wrong as he claimed b would be "int" in my first 
example?

byte a = -128;
auto b = -a;

Or is changing byte to int no typechange?!?

> BTW, Python has what you want - runtime overflow automatically 
> fails over to bignum. But Python is a slow language.
It was someone else who wanted to start a discussion over such a 
feature in D.

I'm fine with the safe signed type I've developed.
The only flaw in my struct for now is that I'm not able to 
overload opCmp in such a way that NaN compared to anything else 
would always be false (either < or >= is true because they can't 
be overloaded separately) :-/
But checking for NaN before any calculation is always the better 
way, so that flaw hits not too hard.
I will do some performance checks to see how "slow" this will 
make some heavy calculations in reality.