On Nov 12, 2007, at 1:02 PM, Alan Watson wrote:
> William D Clinger wrote:
>> The formal syntax says #\XFF is *not* a valid character,
>> [...]
>> 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
>> incorrectly.
>
> The formal syntax also does not indicate that +I, -I, +NAN.0, +NaN.0,
> +INF.0, +Inf.0, etc., are valid numbers, but the second sentence of
> 4.2.8 make its clear that they are.
The implementors of both Larceny and Ikarus either did not read that
sentence or did not interpret it in the same manner.
I do not know what one can conclude about the clarity of that sentence.
-Felix
p.s. Here is demonstration of handling of +Inf.0 by Ikarus and Larceny
% ikarus
Ikarus Scheme (Build 2007-10-31)
Copyright (c) 2006-2007 Abdulaziz Ghuloum
> +Inf.0
Unhandled exception
Condition components:
1. &error
2. &who: read
3. &message: "invalid numeric sequence"
4. &irritants: ("+I")
> (exit)
% larceny
Larceny v0.95 "First Safety" (Nov 7 2007 17:18:52,
precise:Linux:unified)
larceny.heap, built on Wed Nov 7 17:19:23 EST 2007
> +Inf.0
Error: get-datum: Lexical Error: Missing delimiter: +I #<INPUT PORT
*console-input*>
Entering debugger; type "?" for help.
debug> Bad command. ? for help.
debug> a
%
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