Value Preservation and Polysemy -> context dependent integer literals

[Andrei Alexandrescu]

Fawzi Mohamed wrote:
> On 2008-12-01 22:30:54 +0100, Walter Bright <newshound1 at digitalmars.com> 
> said:
> 
>> Fawzi Mohamed wrote:
>>> On 2008-12-01 21:16:58 +0100, Walter Bright 
>>> <newshound1 at digitalmars.com> said:
>>>
>>>> Andrei Alexandrescu wrote:
>>>>> I'm very excited about polysemy. It's entirely original to D,
>>>>
>>>> I accused Andrei of making up the word 'polysemy', but it turns out 
>>>> it is a real word! <g>
>>>
>>> Is this the beginning of discriminating overloads also based on the 
>>> return values?
>>
>> No. I think return type overloading looks good in trivial cases, but 
>> as things get more complex it gets inscrutable.
> 
> I agreee that return type overloading can go very bad, but a little bit 
> can be very nice.
> 
> Polysemy make more expressions typecheck, but I am not sure that I want 
> that.
> For example with size_t & co I would amost always want a stronger 
> typechecking, as if size_t would be a typedef, but with the usual rules 
> wrt to ptr_diff, size_t,... (i.e. not cast between them).
> This because mixing size_t with int, or long is almost always 
> suspicious, but you might see it only on the other platform (32/64 bit), 
> and not on you own.
> 
> Something that I would find nice on the other hand is to have a kind of 
> integer literals that automatically cast to the type that makes more sense.

Wouldn't value range propagation take care of that (and actually more)? 
A literal such as 5 will have a support range [5, 5] which provides 
enough information to compute the best type down the road.

Andrei