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Re: [Chicken-users] ANN: eping
From: |
John Cowan |
Subject: |
Re: [Chicken-users] ANN: eping |
Date: |
Thu, 22 Aug 2013 12:39:09 -0400 |
User-agent: |
Mutt/1.5.20 (2009-06-14) |
Michele La Monaca scripsit:
> I think eval usage (and limitations) can be avoided: For example:
>
> (define-syntax eping
> (syntax-rules ()
> ((_ h)
> (handle-exceptions exn
> (_eping (symbol->string '|h|))
> (let ((t h)) (_eping t))))))
That traps all exceptions, not just undefined-variable ones. In
addition, you need to quote the use of h in the last line, as
it is not a variable. In addition, change |h| to h as noted earlier.
> as regarding (symbol->string '|h|), what you are saying is that in
> this context it is equivalent to (symbol->string 'h) and that one
> happens to work only because Chicken considers '192.168.0.1 a valid
> symbol while in standard Scheme is not. Right?
Right.
> Anyway, it seems to me
> quite a limitation that IP addresses are not valid Scheme symbols and
> something that should be fixed if it is an artificially imposed
> limitation.
The idea is that the lexical scanner should be able to recognize quickly
if something is a number or a symbol, so no symbol is allowed to have a
prefix that is a valid number, with a few historical exceptions.
Chicken takes the approach of scanning a whole symbol, attempting to
convert it to a number, and if that fails assuming it's a symbol.
--
LEAR: Dost thou call me fool, boy? John Cowan
FOOL: All thy other titles http://www.ccil.org/~cowan
thou hast given away: address@hidden
That thou wast born with.
- Re: [Chicken-users] ANN: eping, Michele La Monaca, 2013/08/22
- Re: [Chicken-users] ANN: eping, Michele La Monaca, 2013/08/22
- Re: [Chicken-users] ANN: eping, Michele La Monaca, 2013/08/22
- Re: [Chicken-users] ANN: eping, John Cowan, 2013/08/22
- Re: [Chicken-users] ANN: eping, John Maxwell, 2013/08/22
- Re: [Chicken-users] ANN: eping, Michele La Monaca, 2013/08/22
- Re: [Chicken-users] ANN: eping,
John Cowan <=
- Re: [Chicken-users] ANN: eping, Michele La Monaca, 2013/08/22
- Re: [Chicken-users] ANN: eping, Michele La Monaca, 2013/08/23
- Re: [Chicken-users] ANN: eping, Jörg F . Wittenberger, 2013/08/24
- Re: [Chicken-users] ANN: eping, John Cowan, 2013/08/24
- Re: [Chicken-users] ANN: eping, Michele La Monaca, 2013/08/26