[plt-scheme] Re: getting data out of xexpr's (xml)

From: Stephen De Gabrielle (stephen at degabrielle.name)
Date: Tue Jan 8 09:50:03 EST 2008

Yeah, thanks for raising that.

I think I've seen this in the test cases; I think order-independent list
pattern in plt-match is
    (list-no-order pat ... lvp)       Match arguments in a list in any
, but I haven't tried it yet.

I'm using Matt's example as a base at the moment, and just hoping my data is
ordered consistently, not because the schema/dtd requires it, but because it
is machine generated. (probably too much of an assumption)

By xml-match so you mean sxml-match? if not please tell me, as I have missed

Both sxml-match and SXPath seem to cover all the bases, but I am trying them
one at a time.



On Jan 8, 2008 2:22 PM, Dave Gurnell <d.j.gurnell at gmail.com> wrote:

> My two cents on XML matching:
> I tend to find match and plt-match to be a little restrictive for XML
> pattern matching. The classic example of this is attributes on elements,
> which can arrive in any order. For example:
>     '(a (@ [href "http://www.example.com"]
>            [target "_new"])
>         "Example web site")
> is equivalent to:
>     '(a (@ [target "_new"]
>            [href "http://www.example.com"])
>         "Example web site")
> but you have to match against it with two clauses like this:
>     (match link
>       [`(a (@ [target ,target] [href ,href]) ,text)
>        ...]
>       [`(a (@ [href ,href] [target ,target]) ,text)
>        ...])
> or using nested matches, one for the elements and one for the attributes.
> Perhaps there's an order-independent list pattern in plt-match that I
> don't know about? If not, the XML matching library is probably better for
> this kind of thing. However, xml-match it has its own limitations too (I
> can't remember these off the top of my head: I just remember that writing
> delicious.plt wasn't as straightforward as I might have hoped).
> I haven't tried SXPath yet.
> Cheers,
> -- Dave
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Stephen De Gabrielle
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