From: Stephen Compall <s11@member.fsf.org>
To: "Maciek Godek" <pstrychuj@gmail.com>
Cc: guile-user@gnu.org
Subject: Re: References/locations
Date: Sun, 10 Aug 2008 02:51:39 -0500 [thread overview]
Message-ID: <m2ljz5nw8k.fsf@member.fsf.org> (raw)
In-Reply-To: <e2ceda030808071850uc1640e6kf4ffc33699143fd2@mail.gmail.com> (Maciek Godek's message of "Fri\, 8 Aug 2008 03\:50\:33 +0200")
"Maciek Godek" <pstrychuj@gmail.com> writes:
> I've tried to do it using a "procedure with
> setter", but the problem is that set! doesn't
> evaluate its first argument (as long as it's a
> symbol), so I'd have to wrap everything
> up in macros to obtain:
> (set! (vector-location v 1) 10)
Actually, if you (use-syntax (ice-9 syncase)), you should be able to
define lexical symbol-macros that expand a single symbol, even in a
set! place, something like:
(define v #(1 2 3))
(define-syntax v1
(lambda (stx)
(syntax-case stx ()
(_ v))))
Obviously aliasing will serve:
(define-syntax alias-syntax
(syntax-rules ()
((_ form)
(lambda (stx)
(syntax-case stx ()
(_ (syntax form)))))))
(define-syntax defalias
(syntax-rules stx ()
((_ new form)
(define-syntax new (alias-syntax form)))))
(define-syntax let-alias
(syntax-rules ()
((_ ((new form) ...) body ...)
(let-syntax ((new (alias-syntax form)) ...) body ...))))
(defalias v1 (vector-ref v 1))
(set! v1 42)
(vector-ref v 1) ; => 42
--
a Mr. Fleming wishes to study bugs in smelly cheese; a Polish woman
wishes to sift through tons of Central African ore to find minute
quantities of a substance she says will glow in the dark; a Mr. Kepler
wants to hear the songs the planets sing.
--Carl Sagan, "The Demon-Haunted World"
next prev parent reply other threads:[~2008-08-10 7:51 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-08-08 1:50 References/locations Maciek Godek
2008-08-10 7:51 ` Stephen Compall [this message]
2008-08-15 9:35 ` References/locations Maciek Godek
[not found] ` <e2ceda030808141732r524fc0cehb8ae7c6007550ea6@mail.gmail.com>
[not found] ` <m2wsihltfv.fsf@member.fsf.org>
[not found] ` <e2ceda030808200441q52d9858bv63323055e0f6308a@mail.gmail.com>
2008-08-21 5:05 ` References/locations Stephen Compall
[not found] <cmu-lmtpd-5833-1218211546-4@mail-imap1.uio.no>
2008-08-08 18:34 ` References/locations Kjetil S. Matheussen
2008-08-10 23:00 ` References/locations Maciek Godek
2008-08-15 10:14 ` References/locations Maciek Godek
2008-08-15 13:55 ` References/locations Clinton Ebadi
2008-08-18 8:09 ` References/locations Maciek Godek
2008-08-18 16:15 ` References/locations Clinton Ebadi
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