'int' is enough for 'length' to migrate code from x86 to x64

[Ary Borenszweig via Digitalmars-d]

On 11/20/14, 6:47 AM, Andrei Alexandrescu wrote:
> On 11/20/14 12:18 AM, Don wrote:
>> On Wednesday, 19 November 2014 at 17:55:26 UTC, Andrei Alexandrescu
>> wrote:
>>> On 11/19/14 6:04 AM, Don wrote:
>>>> Almost everybody seems to think that unsigned means positive. It does
>>>> not.
>>>
>>> That's an exaggeration. With only a bit of care one can use D's
>>> unsigned types for positive numbers. Please let's not reduce the
>>> matter to black and white.
>>>
>>> Andrei
>>
>> Even in the responses in this thread indicate that about half of the
>> people here don't understand unsigned.
>>
>> "unsigned" means "I want to use modulo 2^^n arithmetic". It does not
>> mean, "this is an integer which cannot be negative".
>>
>> Using modulo 2^^n arithmetic is *weird*. If you are using uint/ulong to
>> represent a non-negative integer, you are using the incorrect type.
>>
>>> "With only a bit of care one can use D's unsigned types for positive
>>> numbers."
>>
>> I do not believe that that statement to be true. I believe that bugs
>> caused by unsigned calculations are subtle and require an extraordinary
>> level of diligence. I showed an example at DConf, that I had found in
>> production code.
>>
>> It's particularly challenging in D because of the widespread use of
>> 'auto':
>>
>> auto x = foo();
>> auto y = bar();
>> auto z = baz();
>>
>> if (x - y > z) { ... }
>>
>>
>> This might be a bug, if one of these functions returns an unsigned
>> type.  Good luck finding that. Note that if all functions return
>> unsigned, there isn't even any signed-unsigned mismatch.
>>
>> I believe the correct statement, is "With only a bit of care one can use
>> D's unsigned types for positive numbers and believe that one's code is
>> correct, even though it contains subtle bugs."
>
> Well I'm sorry but I quite disagree. -- Andrei
>

I don't think disagreeing without a reason (like the one Don gave above) 
is good.

You could show us the benefits of unsigned types over signed types 
(possibly considering that not every program in the world needs an array 
with 2^64 elements).