<html><head><style type='text/css'>p { margin: 0; }</style></head><body><div style='font-family: Arial; font-size: 12pt; color: #000000'>Plt seems to accept `(a,b'c) as legal r6rs and gives you (a 4 (quote c)) assuming b is defined to be 4 as in the previous message. On the other hand I have just now built ikarus and see that it rejects the expression as having an ill-formed identifier. My initial reading of the the standard is that ikarus is right to reject the expression and plt is wrong to accept it. But I'm kind of a scheme newbie (just trying to be portable) so I'm not sure. Jon On Sunday 28 June 2009 11:10:19 am Jos Koot wrote: > I think 4.2.1  Formal account excludes quotes and commas from identifiers > (except when escaped, of course) They are listed as seperate lexemes. > Jos > > ----- Original Message ----- > From: "Jon Stenerson" <jonstenerson@comcast.net> > To: "Abdulaziz Ghuloum" <aghuloum@gmail.com> > Cc: <plt-scheme@list.cs.brown.edu> > Sent: Sunday, June 28, 2009 5:29 PM > Subject: Re: [plt-scheme] Does `(a,b'c) follow r6rs formal grammar? > > > Then is it a bug in plt scheme that this is accepted? > > > > #!r6rs > > (import (rnrs)) > > (define b 4) > > (display `(a,b'c)) > > > > Using drscheme, the module language, and entering above into definitions > > window. > > > > On Sunday 28 June 2009 02:06:59 am Abdulaziz Ghuloum wrote: > >> On Jun 27, 2009, at 8:36 PM, Jon Stenerson wrote: > >> > Is the expression `(a,b'c)  lexically valid according to r6rs? It says > >> > (section 4.2) that identifiers must be terminated by a delimiter or > >> > end of > >> > input, but this is not true for the identifiers a and b since > >> > neither the > >> > comma nor quote are listed as delimiters. > >> > >> You gave the question and the answer. > >> > >> Aziz,,, > > </div></body></html>