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Re: Sample implementation

This page is part of the web mail archives of SRFI 17 from before July 7th, 2015. The new archives for SRFI 17 contain all messages, not just those from before July 7th, 2015.

>Thanks!  That looks pretty good.  Two nits:
>> (define-syntax set! let*
>>   (syntax-rules ()
>>     ((set! (?e0 ?e1 ...) ?v)
>>      ((setter ?e0) ?e1 ... ?v))
>>     ((set! ?i ?v)
>>      (set! ?i ?v))))
>Why the question-marks?  It makes it look like they have
>some syntactic signifigance, but it is really just a
>naming convention.  Is it a common naming convention?

Well, they do have syntactic significance: they are used to prefix
pattern variables only... :-)

I see it often enough, and the thing is, in large macros that introduce
new bindings they help distinguishing pattern variables from those
introduced by the macro.  For example, I sometimes find myself doing
stupid things like

	(define-syntax foo
	    ((foo e)
	     (let ((e e))  ; evaluate e once
	       ... use e here ...))))

which doesn't work.  If I use ?e for the pattern variable then I am
forced to think about when I am using a pattern variable, which helps me
avoid stupid mistakes like above, and others.