Automatic typing

[Andrei Alexandrescu]

On 7/1/13 7:35 PM, JS wrote:
> On Tuesday, 2 July 2013 at 02:15:09 UTC, Andrei Alexandrescu wrote:
>> On 7/1/13 6:29 PM, JS wrote:
>>> Would would be nice is an experimental version of D where would could
>>> easily extend the language to try out such concepts to see if they truly
>>> are useful and how difficult to implement. e.g., I could attempt to add
>>> said "feature", it could be merged with the experimental compiler, those
>>> interested can download the compiler and test the feature out... all
>>> without negatively affecting D directly. If such features could be
>>> implemented dynamically then it would probably be pretty powerful.
>>
>> I don't think such a feature would make it in D, even if the
>> implementation cost was already sunken (i.e. an implementation was
>> already done and one pull request away).
>>
>> Ascribing distinct objects to the same symbol is a very core feature
>> that affects and is affected by everything else. We'd design a lot of
>> D differently if that particular feature were desired, and now the
>> fundamentals of the design are long frozen. For a very simple example,
>> consider:
>>
>> auto a = 2.5; // fine, a is double
>> ...
>> a = 3;
>>
>
> No, not under what I am talking about. You can't downgrade a type, only
> upgrade it. a = 3, a is still a float. Using the concept I am talking
> about, your example does nothing new.
>
> but reverse the numbers:
>
> auto a = 3;
> a = 2.5;
>
> and a is now a float, and your logic then becomes correct EXCEPT a is
> expanded, which is safe.
>
> I really don't know how to make it any clearer but I'm not sure if
> anyone understands what I'm talking about ;/

You can definitely assume you are being well understood. That's going to 
break a lot of code because of e.g. calls to overloaded functions in 
between changes of type.

Just drop this. Not only it won't make it into D, it's also not 
particularly interesting.


Andrei