Hi to everyone!,
I'm trying to test the mechanization of Redex's semantics done in [1],
against the present version of racket, 8.3. I'm using the random-match-test.rkt
module from [1] to generate random grammars, patterns and terms, and to
test them
using the proposed mechanization of Redex in [1] and the actual
implementation of
it, in racket 8.3.
In doing it, I've found an example that I cannot explain in terms of my
understanding
of the behavior of the name pattern:
(define-language L [A (name x B)]
[B (hole (name x (hole hole)))])
(redex-match L (name x A)
(term (hole (hole hole))))
The result of the previous match is:
(list (match (list
(bind 'A '(hole (hole hole)))
(bind 'x '(hole hole))
(bind 'x '(hole (hole hole)))
(bind 'x '(hole (hole hole))))))
Which shows that 'x' is bound to different, non-equivalent, terms. While
I've never used the pattern name explicitly in such a way, while defining
grammars, I'm still curious about what is going on here. Even more, I would
have thought that the following match would return the same result as the
previous:
(redex-match L (name x (name x B))
(term (hole (hole hole))))
where I just replaced the non-term A by the rhs of its only production, but
what I obtain is:
#f
As a side note, the mechanization of Redex in [1] just returns something
equivalent to:
(bind 'x '(hole (hole hole)))
In both cases. Does anyone understand the behavior of the shown example
under racket 8.3?
Thanks in advance!,
Mallku
[1] : https://link.springer.com/chapter/10.1007%2F978-3-642-25318-8_27
El jueves, 9 de diciembre de 2021 a las 13:20:31 UTC-3, Mallku Ernesto
Soldevila Raffa escribió:
> Thanks a lot for the info! If I found any mismatches, I'll report it.
>
> Regards,
> Mallku
>
> El miércoles, 8 de diciembre de 2021 a las 23:32:25 UTC-3, Robby Findler
> escribió:
>
>> I'm sorry, my sentence was ambiguous! I'm saying that I don't know of any
>> other work that is specifically focused on the semantics of Redex. (Of
>> course, there may be work I'm not aware of.)
>>
>> The paper is still a good match, I believe, yes. You're right that the
>> syntactic checks for well-formed grammars have tightened since that era,
>> but if the program is valid, then I think it should match; the underlying
>> algorithms have not changed, only bug fixes have happened.
>>
>> Of course, if you find that this isn't the case, I'd be very interested
>> to hear more :)
>>
>> Robby
>>
>>
>>
>> On Wed, Dec 8, 2021 at 6:34 PM Mallku Ernesto Soldevila Raffa <
>> mallku...@gmail.com> wrote:
>>
>>> I beg your pardon!, I'm not understanding the answer, what is it that
>>> might be specific of Redex?
>>>
>>> I suspect that the answer is that there isn't some recent work on formal
>>> semantics specifically about Redex. In that case, does anybody know if
>>> the
>>> already mentioned paper [1] is still a good match for today's semantics
>>> of
>>> Redex? The paper provides a mechanization of the model in Redex,
>>> together
>>> with some tools to test it. Of interest is a tool that asks Redex to
>>> generate
>>> random patterns and terms that match against them, and tests if the
>>> mechanized model is capable of reproducing the matching (or that is what
>>> I suspect that the tests are doing :P ). It was possible to run the
>>> mechanization
>>> on a recent version of Redex, but the generated patterns are ill-formed
>>> (e.g., in-hole p1 p2, where p1 contains more than 1 hole). Of course I
>>> could
>>> provide more details about the error, but I don't know if it is of
>>> interest, it's
>>> a mechanization written for the Redex version that comes with Racket 5.*
>>> or something like that.
>>>
>>> Thanks!,
>>> Mallku
>>>
>>>
>>> [1] : https://link.springer.com/chapter/10.1007%2F978-3-642-25318-8_27
>>>
>>> El miércoles, 8 de diciembre de 2021 a las 21:03:44 UTC-3, Robby Findler
>>> escribió:
>>>
>>>> I think that might be it specifically about redex, I am sorry to say.
>>>>
>>>> Robby
>>>>
>>>> On Wed, Dec 8, 2021 at 5:28 PM Mallku Ernesto Soldevila Raffa <
>>>> mallku...@gmail.com> wrote:
>>>>
>>>>> Hi community!,
>>>>> I'm interested in understanding the semantics of PLT Redex, since we
>>>>> are working on a tool
>>>>> to translate fragments of Redex models to Coq. At the moment, we just
>>>>> have a
>>>>> mechanization in Coq of the semantics proposed in a ~10 years old
>>>>> paper [1]. Does
>>>>> anybody know if there is an updated work on formal semantics of Redex?
>>>>>
>>>>> Thanks in advance!,
>>>>> Mallku
>>>>>
>>>>> [1] : https://link.springer.com/chapter/10.1007%2F978-3-642-25318-8_27
>>>>>
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>>>>>
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>>
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