Re: [Scheme-reports] auxiliary syntax

["Aaron W. Hsu" <arcfide@x>]

On Sat, 2013-01-12 at 11:48 +0900, Alex Shinn wrote:
> Rather, it's a type of low-level macro that looks at symbol names, and
> how we could potentially do the same thing with high-level macros. 

Okay, I was holding off until now, but now I think I gotta say that this
has already been done and has existed in an usable state for a long time
now in Chez Scheme and probably elsewhere that uses the `syntax-case'
system.

In particular, Chez extends 'syntax-rules' to allow for a guard clause
which allows one to unhygienically match against a literal if so
desired.

(define-syntax match-my-plus
  (syntax-rules ()
    [(_ plus) (eq? '+ (syntax->datum #'plus)) #t]
    [(_ else) #f]))

This will give true only in the case where we have (match-my-plus +) and
it will not return true for something like (let () (alias blah +)
(match-my-plus blah)). 

I fail to see what the problem is here.

-- 
Aaron W. Hsu | arcfide@x | http://www.sacrideo.us
לֵ֤ב חֲכָמִים֙ בְּבֵ֣ית אֵ֔בֶל וְלֵ֥ב כְּסִילִ֖ים בְּבֵ֥ית שִׂמְחָֽה׃


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