This page is part of the web mail archives of SRFI 109 from before July 7th, 2015. The new archives for SRFI 109 contain all messages, not just those from before July 7th, 2015.
Per Bothner scripsit: > As a matter of style, I think this questionable - duplicating > definitions from existing standards is a mistake. (Where would > you stop? Duplicate the entire definition of <expression>?) No, I'm referring to SRFI-109, and only the definitions of nested-comment, intraline-whitespace, line-ending, letter, digit, and hex-digit that are explicitly linked to R7RS. That would add about nine lines to the SRFI, but would eliminate the dependency on R7RS in the formal part. > Is there any Scheme implementation where (eq? (make-string 0) > (make-string 0)) returns #t? Chez, Shoe, Oaklisp are the only ones I have right now that do so. The last two probably don't matter in practice, but Chez is still an important Scheme, even if it doesn't get as much publicity as the major open-source varieties. > I tweaked the draft to discuss this (theoretical) possibility: > > Note that R6RS and R7RS allows eq? to return #t for distinct calls to > (make-string 0). A hypothetical implementation that does so needs > to initialize $<<$ and $>>$ some other way. That's a first step, but not, I think, sufficient. > SRFI-109 can't be implemented by a portable library anyway, so it > seems fine to make such a requirement. Given that it would be a > really weird Scheme implementation where it is an issue. SRFI 10 can't be implemented portably *today* for lack of a portable readtable interface. But definitions of $string$ and $construct$:* can certainly be written portably modulo this one issue. In order to make them fully portable, the SRFI must say that the values of $<<$ and $>>$ are unique objects whose values are unspecified, and all definitions of $string$ and of $construct$:* must be written so as to take this into account. -- John Cowan cowan@xxxxxxxx http://www.ccil.org/~cowan Statistics don't help a great deal in making important decisions. Most people have more than the average number of feet, but I'm not about to start a company selling shoes in threes. --Ross Gardler