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Re: [Scheme-reports] valid implementation of call-with-input-file?


On Wed 22 Aug 2012 01:54, Alex Shinn <alexshinn@x> writes:

> You acknowledged that whether we put it in the
> small language or not, people will have raise-continuable.
> This is incompatible with your definition of c-w-i-f.

No, this is not.  If a user implements raise-continuable, it does not
use the exception mechanism.

> No one is talking about non-local exits that do not use
> the exception mechanism.

Why did you mention amb, then?

>>> `exception-protect' is useful but is only an 80% solution.
>>> It is therefore not appropriate for call-with-input/output-file.
>> This is ridiculous.  The same argument would support not closing the
>> file after a normal exit from the c-w-i-f procedure.
> No it would not, because that's the existing c-w-i-f semantics
> (that the port is closed after the first normal return).
> You are proposing a change to the semantics which could
> break existing R6RS programs, and existing R5RS programs
> that use an exception system.

Since when do you care about R6RS?  It doesn't matter though, the answer
here is still no: R6RS programs use different libraries.  c-w-i-f in
R6RS does not have the be the same one as in R7RS.

As R5RS has nothing to say about exception systems, it cannot possibly
break these.


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