* Quasi-macros ?
@ 2003-02-09 19:23 Joris van der Hoeven
2003-02-10 16:33 ` david
0 siblings, 1 reply; 2+ messages in thread
From: Joris van der Hoeven @ 2003-02-09 19:23 UTC (permalink / raw)
Hi,
Consider the following piece of code:
(define (define-table-decls name l)
(if (null? l) l
(cons `(hash-set! ,name ',(caar l) ',(cadar l))
(define-table-decls name (cdr l)))))
(define-macro (define-table name . l)
`(begin
(define ,name (make-hash-table ,(+ (* (length l) 2) 1)))
,@(define-table-decls name l)))
(define-table test
(hello hoi)
(joke grapje)
(gnu blauwbilgorgel))
This allows you to define many tables in a nice way.
Sometimes however, it would be nice to write things like
(define-table the-question
(two ,(+ 1 1))
(four ,(* 2 2)))
Someone has an idea of how to do this *without* explicitly
using 'eval', which might result in loosing the context?
Thanks, Joris
-----------------------------------------------------------
Joris van der Hoeven <vdhoeven@texmacs.org>
http://www.texmacs.org: GNU TeXmacs scientific text editor
http://www.math.u-psud.fr/~vdhoeven: personal homepage
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* Re: Quasi-macros ?
2003-02-09 19:23 Quasi-macros ? Joris van der Hoeven
@ 2003-02-10 16:33 ` david
0 siblings, 0 replies; 2+ messages in thread
From: david @ 2003-02-10 16:33 UTC (permalink / raw)
Cc: guile-user
On Sun, Feb 09, 2003 at 08:23:23PM +0100, Joris van der Hoeven wrote:
>
> (define (define-table-decls name l)
> (if (null? l) l
> (cons `(hash-set! ,name ',(caar l) ',(cadar l))
> (define-table-decls name (cdr l)))))
>
> (define-macro (define-table name . l)
> `(begin
> (define ,name (make-hash-table ,(+ (* (length l) 2) 1)))
> ,@(define-table-decls name l)))
>
> (define-table test
> (hello hoi)
> (joke grapje)
> (gnu blauwbilgorgel))
>
> This allows you to define many tables in a nice way.
> Sometimes however, it would be nice to write things like
>
> (define-table the-question
> (two ,(+ 1 1))
> (four ,(* 2 2)))
>
> Someone has an idea of how to do this *without* explicitly
> using 'eval', which might result in loosing the context?
It looks like quasiquote has special behaviour when it comes to
quoting himself... However, with a bit of hacking you can do what you
want.
(define (define-table-decls h l)
(define (sub ll) (hash-set! h (car ll) (cadr ll)))
(for-each sub l))
(define-macro (define-table name . l)
`(begin
(define ,name (make-hash-table ,(+ (* (length l) 2) 1)))
(define-table-decls ,name ,(list 'quasiquote l))))
(define-table the-question
(two ,(+ 1 1))
(four ,(* 2 2)))
--
David Allouche | GNU TeXmacs -- Writing is a pleasure
Free software engineer | http://www.texmacs.org
http://ddaa.net | http://alqua.com/tmresources
david@allouche.net | allouche@texmacs.org
TeXmacs is NOT a LaTeX front-end and is unrelated to emacs.
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2003-02-09 19:23 Quasi-macros ? Joris van der Hoeven
2003-02-10 16:33 ` david
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