[Grace-core] Traits as non-objects

[James Noble]

> I promised to write up a description of (my interpretation of) the trait inheritance proposal from Denver.  Here it is.  The file is in NewOOL/GracePaper/Traits/NonObject Traits

indeed! thanks for doing that.  A few comments/questions:

 - how does this work with modules?    
    in particular - 
     how do you inherit/instantiate a trait in another module?
     modules & dialects now have to inherit from traits - 
      or not be extensible via inheritance    

 - do we want trait aliases / definitions 
      trait NumberSet = trait Set<Number>  

 - can object constructors have "naked" declarations - 
      or are declarations now only in traits?

 - I'm pretty sure Eiffel's rename (and I imagine Marco's work) "deeply" renames methods..
 
 - Do you still run initialisers for deleted fields?

 - what's on the right-hand-side of a "-" operator?

 - if we decide we want trait composition   (not really a question)
   it seems the proposal on trait composition operators is orthogonal to the proposal
    about traits per se.  With any of proposals, we could allow trait composition 
    (e.g. in inherits clauses),
   - or have single inheritance
   - or the Newspeak (and now Dart) model of implicit mixins...

 - the conceptual model of traits seems to require at least one
     extra concept - traits - without eliminating anything. 
     objects are still created by factory.new (rather than new X or object X?)
     so we have the complexity of factories and classes, now with traits.

- alternatively couldn't you just make do with classes?
    (with or without (orthogonal) composition operators)
 
I'm sorry if it comes across as being picky: but we just haven't 
thought through most of the designs 

I fear we'll end up talking about this again tomorrow:
actually I don't mind we're talking about it but we should just
do the other stuff first.

James