[plt-scheme] Re: [Larceny-users] side effects in R6RS modules

From: Robby Findler (robby at eecs.northwestern.edu)
Date: Tue May 5 12:32:48 EDT 2009

I think this is more than just about portability since implementations
are free to choose one semantics on one day and another on other, but
perhaps in practice portability is where this ends up being a real


On Tue, May 5, 2009 at 11:23 AM, Matthias Felleisen
<matthias at ccs.neu.edu> wrote:
> The argument is about unintentional ambiguous interpretations.
> When editors of a language report intentionally add ambiguous
> interpretation, I think they reject some amount of portability, and that's
> the issue you'd bring up then if you were allowed to argue with them.
> Though now that the steerers also become the steered, there will be just the
> one true view.
> On May 5, 2009, at 11:21 AM, Abdulaziz Ghuloum wrote:
>> On May 5, 2009, at 5:44 PM, Matthias Felleisen wrote:
>>> In PL, such questions should be decided via mathematical models that
>>> do not depend on machines and compilers. That's the only way to truly
>>> disambiguate the English in a spec.
>>> For whatever reasons, the editors moved the only piece of mathematics
>>> semantics (which doesn't include modules and macros) to the appendix,
>>> for reasons that still escape me. Well, they don't really. If you
>>> don't have a tool for arbitrating two distinct interpretations of
>>> an informal document, you can always claim that both are correct and
>>> if you so desire, you can claim one of them is, eh, smart? :-)
>> Such tool helps indeed, but it's not the only way to arbitrate
>> the different interpretations of the document.  As a matter of
>> fact, the document in question explicitly states that both of
>> these interpretations (and many others) are allowed and are
>> correct with regard to satisfying the report's requirements.
>> The issue here is that the library in question has nonportable
>> semantics (as should be clear from reading the document) but
>> this is the same as depending on any other unspecified behavior
>> (such as one implementation's evaluation order: left-to-right,
>> right-to-left, ...).  You're not arguing that there must be
>> only one valid and true interpretation of the report, right?
>> Aziz,,,
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