Joe Marshall wrote:
> Obviously Will was not suggesting that compilers reject
> programs that cannot be proven to terminate.
Your statement seems to miss my point but, as I said in another
thread, I've given up on R6RS and only mean to kibbitz a little...
sorry if I went too far.
-t
>
> On 2/24/07, Thomas Lord <lord_at_emf.net> wrote:
>> I think the standard has failed to be a lisp, and failed in the
>> Scheme tradition, if it does not permit viable non-standard
>> interpretations of programs which are divergent under the
>> standard (see my earlier post "Mathematical Foundations").
>>
>> For example, suppose that a procedure which is not provably
>> terminating in a portable interpretation has the property that,
>> nevertheless, we can say that *if* it terminates, the type of
>> the return value is CHAR?. Further, suppose the procedure
>> is invoked in a context that is only strict in the type of the
>> return value.
>>
>> Must R6RS prohibit an implementation from completing this
>> computation?
>>
>> Before answering, please read "On Games and Numbers".
>>
>> Regards,
>> -t
>>
>>
>>
>> Arthur A. Gleckler wrote:
>> > On Feb 24, 2007, at 4:54 PM, William D Clinger wrote:
>> >
>> >> Matthias Felleisen wrote:
>> >>> 2. Naturally I don't reject type systems per se but I think that a
>> >>> serious
>> >>> language definition shouldn't introduce such systems without
>> >>> specifying
>> >>> them. Otherwise a language/implementation will appear
>> whimsical to
>> >>> programmers.
>> >>
>> >> The current draft already mandates hundreds of runtime
>> >> exceptions whose whimsical purpose is to make programs
>> >> that violate the requirements of the R6RS less likely
>> >> to run to completion. Why should that kind of whimsy
>> >> be limited to run time?
>> >
>> > My only concern is that an error in one part of my program should not
>> > prevent me from running another part of the program. The thing I most
>> > dislike about most statically typed language implementations is that
>> > they prevent me from testing a program that isn't yet completely
>> > type-correct when I'm not even planning to invoke the broken part of
>> > the program. I suppose that this suggestion only allows, but doesn't
>> > require, compiler writers to signal errors it can detect at compile
>> > time. Still, I'd rather not encourage this behavior if it makes it
>> > impossible to run programs that are not yet completely correct.
>> >
>> > _______________________________________________
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>> > r6rs-discuss_at_lists.r6rs.org
>> > http://lists.r6rs.org/cgi-bin/mailman/listinfo/r6rs-discuss
>> >
>>
>>
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>
>
Received on Sun Feb 25 2007 - 00:22:56 UTC