Can we just have struct inheritence already?

[Ola Fosheim Grøstad]

On Sunday, 9 June 2019 at 21:35:19 UTC, Ola Fosheim Grøstad wrote:
> On Sunday, 9 June 2019 at 21:13:50 UTC, Manu wrote:
>> This is NOT polymorphism, we're not talking about 
>> polymorphism, I wish people would not change the topic.
>
> Well, it sort of is. Consider a situation where you have 
> assignment defined for the super class, and where there is a 
> field in the subclass that depends on a field in super.

Or rather: you sometimes have a dependency, then you want the 
type system to prevent assignments through the base class. 
However, in other cases you don't have a dependency, then you do 
want to be able to assign through the base class.

But you need something syntactical to tell the type system that 
such dependencies exist.