[plt-scheme] Question on Syntactic Sugar

If it is, and J.T. is working outside modules, then
the following trick might help:

   > (compile-allow-set!-undefined #t)
   > > (define-syntax setq
     (syntax-rules ()
       [(setq rest ...)
        (set! rest ...)]))
   > (setq f 4)
   > f
   4

/Jens Axel

Felix Klock's PLT scheme proxy wrote:
> It is not clear from J.T.'s email whether setq is sometimes used in the 
> dated psuedo-lisp to introduce bindings for global variables from within 
> a local scope.
> 
> For example, in some systems you can use the following trick to add a 
> global binding for global-z, *without* ever writing anything like 
> (define global-z 'to-be-defined)
> 
> (let ((x EXP1) (y EXP2))
>    (set! global-z (list x y)))
> 
> I suspect there is a way to get a similar effect using MzScheme's 
> namespaces, but I do not know what it is.
> 
> In any case, I think Dave has the right idea (modulo the need for a 
> literals list in his syntax-rules form, as he pointed out in a 
> subsequent email).
> 
> I'm just not sure if such a simple replacement of setq with define is 
> going to be sufficient for J.T.'s purposes.
> 
> -Felix
> 
> On Nov 1, 2007, at 3:34 PM, Dave Herman wrote:
> 
>> Would this get the job done?
>>
>> (define-syntax setq
>>   (syntax-rules setq
>>     [(setq rest ...) (define rest ...)]))
>>
>> Dave
>>
>> J.T. Hurley wrote:
>>> I've been working on an "overlay" for Scheme that would let a user
>>> enter a set of extremely dated pseudo-lisp from a puzzle book as
>>> Scheme code in MzScheme.
>>> For the most part, this has been trivially easy, just using (define
>>> old-term new-term). However, I've hit a huge snag.
>>> The old pseudo-lisp uses setq instead of define, and MzScheme throws
>>> an error if you use define within in a definition. What would be the
>>> easiest way to get around this and create an expression equivalent to
>>> (define setq define)?
>>> Thank you in advance,
>>> J.T.
>>> _________________________________________________
>>>   For list-related administrative tasks:
>>>   http://list.cs.brown.edu/mailman/listinfo/plt-scheme
>>
>> _________________________________________________
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> 
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