[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Scheme-reports] Fwd: Symbol escapes - clarification

38 years of using email is apparently not enough for me to get it right, 
I sent this unintentionally only to John before it was finished. 

John, please ignore the copy I sent you.

Begin forwarded message:

From: Vincent Manis <vmanis@x>
Date: 2012 January 9 08:53:27 PST
To: John Cowan <cowan@x>
Subject: Re: [Scheme-reports] Symbol escapes - clarification

On 2012-01-09, at 08:12, John Cowan wrote:
I am not sure I understand this. \-escaping *is* allowed within
|-escaping, so |(\x3BB;)| is the identifier "parenthesized lambda".
Indeed, there is a ticket pending to disallow \-escaping by itself and
allow it only within |-escaping.  That would allow \ to be an ordinary
identifier character.
I'm confused. The syntax in sec 7.1.1 appears to say that a symbol
element is any character except | or \. That seems inconsistent with
John's explanation above.

Also, I'd also recommend that the backslash sequence \| be added, so
you can write the identifier \a|b/ as |\\a\|b/|, should you be so inclined.
That was a poor choice for an example. |\a|b/ is a silly identifier| would 
be a better one. 

It was a conscious decision to make vertical bars delimit the symbol, in
the same way that quotes delimit a string.  The wording of 2.1 is meant
to imply this: a symbol can begin with |, contain arbitrary characters
or inline hex escapes, and end with |.

-- vincent
Scheme-reports mailing list