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Re: sxml-match bad pattern syntax
From: |
tomas |
Subject: |
Re: sxml-match bad pattern syntax |
Date: |
Tue, 28 Dec 2021 08:19:04 +0100 |
On Tue, Dec 28, 2021 at 01:21:31AM -0500, Thien-Thi Nguyen wrote:
>
> In an effort to join the current millennium,
:-)
> i have started to
> play w/ Guile 2.x's SXML facilities. Good stuff! I've run into
> a problem, however, and hope i can get help resolving it here.
>
> The following small program attempts to use ‘sxml-match’ to
> remove an unwanted attribute from a (well-formed) SXML snippet.
> #!/usr/bin/guile -s
> !#
> (use-modules
> (sxml match))
>
> (define (unbogus x)
> (sxml-match x
> ((a (@ . ,attrs) ...)
> `(a (@ ,@(delete '(shape "rect") attrs)) ...))))
I /think/ the ellipsis is at a wrong place there. Note that I'm coming
from "traditional" match, and I just have wrapped half of my brain
around that (which, BTW, is somewhat painful :-)
So take this with a grain of salt.
* Phenomenology (aka: I barely know what I'm doing):
If you replace your ellipses above by ". ,rest", things seem to work:
(define (unbogus x)
(sxml-match x
((a (@ . ,attrs) . ,rest)
`(a (@ ,@(delete '(shape "rect") attrs)) . ,rest))))
(unbogus '(a (@ (shape "rect") (href "foo.html")) "kid"))
=> (a (@ (href "foo.html")) "kid")
* Philosophy (aka blah, blah)
If those ellipses resemble what match do, I think they are wrong there:
(@ . ,attrs) ...
would mean zero or more times the shape "(@ . ,attrs)". I think this
isn't what you want.
Put grains of salt everywhere :)
Cheers
--
t
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