[Grace-core] Class syntax and type parameters

[Marco Servetto]

>because my categories are about the structure of language, not about how it's implemented.
Generational like C++ is about the language.
The type system only reason on non polymorphic type, and do the
expansion in order to to the typechecking.
So the language do not have  polymorphic types.

>well it works if you have classes that can be generic
without having generic methods. Currently Grace doesn't.
I'm not sure to understand. Grace is designed for beginners. Do you
want to teach how to implement /use generic methods to beginners or
not?