Re: [Caml-list] xpath or alternatives

From: Till Varoquaux <till@pps.jussieu.fr>
To: Richard Jones <rich@annexia.org>
Cc: caml-list@inria.fr
Subject: Re: [Caml-list] xpath or alternatives
Date: Wed, 30 Sep 2009 09:33:07 -0400	[thread overview]
Message-ID: <9d3ec8300909300633t51db9ed9jf3ad15e6b0551c1e@mail.gmail.com> (raw)
In-Reply-To: <20090930125904.GA5126@annexia.org>

OCamlduce (Alain correct me if I am wrong) basically maintains two
separate type systems side by side (the Xduce one and the Ocaml one).
This is done in order to make Ocamlduce maintainable by keeping a
clear separation. As a result you have to explicitly convert values
between type systems using {:...:}. These casts are type safe but do
lead to some work at runtime.

Also note that ocaml's string are Latin1 and not String in the XML world. So:

 let devs = match xml with
   | {{ <domain>[<devices>[<source dev=(Latin1 & dev) ..>[]]] }} -> {:dev:}
   | {{ <domain>[<devices>[<source file=(Latin1 & file) ..>[]]] }} ->
{:file:} in

Should work (I'm rusty and have nothing to check handy).

Till

On Wed, Sep 30, 2009 at 8:59 AM, Richard Jones <rich@annexia.org> wrote:
> On Wed, Sep 30, 2009 at 12:57:23PM +0100, Richard Jones wrote:
>> On Wed, Sep 30, 2009 at 04:05:03AM -0700, Dario Teixeira wrote:
>> > Hi,
>> >
>> > Ocamlduce has been mentioned before in this thread, but I didn't catch
>> > the reason why it has been discarded as a solution.  Is it because you
>> > don't want to carry the extra (large) dependency, or is there some other
>> > reason?
>>
>> Actually the reason is that I thought it wasn't available for 3.11.1,
>> but I just checked the website and it is, and ocamlduce does seem to
>> be the obvious solution for this problem.  (However I'll need to try
>> and see if I can come up with the equivalent code).
>
> Do any cduce developers want to give me a clue here?  It would seem
> like I need something along these lines:
>
>  let devs = match xml with
>    | {{ <domain>[<devices>[<source dev=(String & dev) ..>[]]] }} -> dev
>    | {{ <domain>[<devices>[<source file=(String & file) ..>[]]] }} -> file in
>
> However according to the compiler, devs has type <XML>.  In any case,
> I think I may need either the map or map* operator, since I want to
> match all, not just the first one.
>
> Rich.
>
> --
> Richard Jones
> Red Hat
>
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