[Grace-core] Numbers and structural typing

[Marco Servetto]

Hi Kim, thanks for giving me a solution without explaining what is the problem.

I see that there is something wrong around what I pointed out, but  I
have no clear idea what.

Also, what is the semantic of types in grace? I tough they was only
for extra safety/type safety, right? and a class is only a wrapped
function, so the object should have no idea who created him... plus
the brand would just be a label, actually stored in a field, right?
thus an object may declare to be of any brand in the untyped version.
what happen then? it must be well defined, and I can not see an end of
my reasoning here.