(This originated on the chibi-scheme list, but it transcends Chibi, so I am cross-posting to the WG1 and scheme-reports lists. The usual apologies for dupes.)
Alex Shinn scripsit: > On Mon, Apr 16, 2012 at 1:37 PM, Alan Watson <[email protected]> wrote: > > Consider: > > > > a'b > > > > According to the grammar rules, this is the identifier |a| followed by > > the token ' followed by the token |b|. However, the third paragraph > > of §7.1.1 says: "Identifiers that do not begin with a vertical bar > > are terminated by a ⟨delimiter⟩ or by the end of the input." Since > > ' is not a delimiter, this input is invalid. [snip] > The general policy is that Chibi implements what is simplest, so long > as it obeys the standard and isn't overly surprising. By far the > simplest thing to do here is to treat it as a delimiter, and this is > what many other implementations do. I tested "(list 'a'b)" on 42 Schemes. (Note: I am no longer testing with both Ikarus and Vicare, just with Vicare. They usually give the same answer, and if not, it's usually a bug or implementation gap in Ikarus, which is no longer being developed.) Returned (a b): Racket, Gauche, MIT, Gambit, Chicken, Scheme48/scsh, Kawa, Chibi, Chez, Vicare, NexJ, STklos, KSi, SigScheme, Scheme 9, BDC, XLisp, Rep, Oaklisp, Spark, Owl Lisp Returned (a'b): Bigloo, Guile, SISC, SCM, Shoe, TinyScheme, Dream, Scheme 7, Schemik, Elk, UMB, VX, Sizzle, Inlab Syntax error: Vicare, Ikarus, Mosh, IronScheme, SXI, MScheme I suspect that a lot of implementations think it's simplest to just gobble up what they see until they get to an unquestioned delimiter. -- John Cowan http://www.ccil.org/~cowan [email protected] "After all, would you consider a man without honor wealthy, even if his Dinar laid end to end would reach from here to the Temple of Toplat?" "No, I wouldn't", the beggar replied. "Why is that?" the Master asked. "A Dinar doesn't go very far these days, Master. --Kehlog Albran Besides, the Temple of Toplat is across the street." The Profit _______________________________________________ Scheme-reports mailing list [email protected] http://lists.scheme-reports.org/cgi-bin/mailman/listinfo/scheme-reports
