[Grace-core] Grace feedback

[James Noble]

> However, I don't know how to do ADTs without types.  ADTs  
> fundamentally need types to achieve the encapsulation

sure - but these could be static types or dynamic types...

> One thing that we have not discussed is whether there should be some  
> sort of "protect" or "narrow" operation that hides some operations  
> on an object from certain clients, while exposing them to other  
> clients.

right - so long as those restrictions are checked dynamically if  
necessary,
and the static restrictions are no stronger than the dynamic ones,
then everything should hold together and there is no way of "cheating"
statically to get around any restrictions.

Where things get super-hairy is in say Java 1.5, with different static
and dynamic systems, neither stronger than the other!  So there
are static things that succeed dynamically, and things that
pass statically that fail dynamically :-).

James