[plt-scheme] redex question: use ordering to force determinism?

No reason to be sorry. Relations are, well, relations. And meta- 
functions denote, oh, eh, functions.


On Sep 8, 2008, at 2:42 PM, Robby Findler wrote:

> There is no way to do that, sorry. (metafunctions do have that  
> property, tho)
>
> Robby
>
> On Mon, Sep 8, 2008 at 1:41 PM, John Clements  
> <clements at brinckerhoff.org> wrote:
>> Redex is designed to handle one-to-many reduction relations  
>> gracefully.  Is
>> there some way to squelch this and specify that only the first  
>> applicable
>> rule is to be used?  That is, I would like to implicitly quantify  
>> each
>> reduction rule with a side-condition that specifies that none of the
>> textually earlier rules match.
>>
>> My conjecture is that no such mechanism exists, because the  
>> beginner.ss
>> example includes things like this:
>>
>>  ((symbol=? 'x_1 'x_2) . ==> . ,(if (eq? (term x_1) (term x_2))  
>> (term true)
>> (term false)))
>>   ((side-condition (symbol=? v_1 v_2)
>>                    (or (not (and (pair? (term v_1))
>>                                  (eq? (car (term v_1)) 'quote)))
>>                        (not (and (pair? (term v_2))
>>                                  (eq? (car (term v_2)) 'quote)))))
>>    . e==> .
>>    "symbol=?: expects argument of type <symbol>")
>>
>>
>> ... yikes!
>>
>> Is there some reason not to allow relations to be ordered in this  
>> way?  Am I
>> missing some newer feature?
>>
>> Many thanks,
>>
>> John
>>
>>
>>
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