[Visionaries] WebScheme Update

[Peter Minten]

Hi folks,

I tackled some of the problems in the WebScheme design during the last days and 
now have a brand new working model (that is, until I find a case that breaks it 
 :-).

The major change is the introduction of pass-by-value. From now on 
(define),(set!) and (let) use pass-by-value. Everything else is 
pass-by-reference. There are (define-ref) and (set-ref!) methods to allow 
pass-by-reference for (define) and (set!) too. In (let) you can make a clause 
pass-by-reference by putting 'ref' in as the first word like this (let ((ref a 
b)) ...). I added this feature because in most cases pass-by-reference is wanted 
in assignments.

A second 'feature' is the dumping of attributes. The attribute stuff was just a 
way to say (define foo bar) so it's better to do that clearly. That's why I 
changed the definition of (define) to: (define target value . forms) where forms 
are executed after the assigment, in order and in the scope of the define. I 
also added a special variable called define-target (for now) that is always 
reference to the target and available from every function. So now attributes are 
normal functions that change define-target.

Finally with the attributes going away I got the square braces back, but not for 
long :-). The C type array notation now works in WebScheme for arrays, but it 
also works for hashes and all that jazz. The syntax expansion is: a[b] -> 
(a.index b).

Greetings,

Peter