equivariant functions

[Frits van Bommel]

Andrei Alexandrescu wrote:
> Benji Smith wrote:
>> Andrei Alexandrescu wrote:
>>> What do you think? I'm almost afraid to post this.
>>
>> It's a lot to swallow all at once, especially if the equivariance 
>> applies to all type/subtype relationships, and not just the mutability 
>> of a value. Am I reading that right?
> 
> 
> Yes.

Are you sure about that? How would this work for interfaces and classes 
that implement them?
Remember: Interface references currently don't point to the object 
vtable at the beginning of an object but to the interface vptr inside 
the object.
Unless that was changed/is going to change? (For example, interface 
references could be implemented as "fat pointers" consisting of { object 
ptr, interface vptr } instead of the current { pointer to interface vptr 
}, which could make this easier to implement)