[r6rs-discuss] Lexical Syntax
William D Clinger
will at ccs.neu.edu
Sun Nov 11 09:59:30 EST 2007
Alan Watson wrote:
> Furthermore, it appears that both #\xff and #\XFF are valid characters,
> but only the first of \xff; and \XFF; is a valid inline hex escape. Is
> this the intent of the editors?
The formal syntax says #\XFF is *not* a valid character,
so I (and Larceny v0.95 "First Safety", whose reader was
mostly machine-generated from a formal description of the
syntax, and also Ikarus Build 2007-10-31) regard both
#\XFF and \XFF; as illegal.
The only reason I can see to regard #\XFF as a valid
character is the following sentence in R6RS 4.2.6:
Case is significant in #\<character>, and in
#\<character name>, but not in #\x<hex scalar value>.
I believe that sentence was intended to say that case
is not significant in the <hex scalar value> part of
#\x<hex scalar value>, but the sentence was worded
Regardless of the editors' intent, I believe the best
way to resolve the inconsistency is to interpret that
sentence as Aziz and I have.
More information about the r6rs-discuss