[xsl] Re: Re: Higher-Order Functions in XPath 2.0

Subject: [xsl] Re: Re: Higher-Order Functions in XPath 2.0
From: Dimitre Novatchev <dnovatchev@xxxxxxxxx>
Date: Thu, 17 Jan 2002 08:01:45 -0800 (PST)
Joerg Pietschmann <joerg dot pietschmann at zkb dot ch> wrote:

> Hi Dimitre,
> sorry, i'm late.
> Some comments, just in case you want to amend your proposal
> or you are asked to clarify some points:

I think anyone can reply to my message in www-xpath-comments@xxxxxx

> Point 3.) This essentially says there is currently no facility
> to iterate over two or more sequences in parallel rather than
> on the cartesian product. This is especially bad because
> there is no reasonable way to emulate this using the "for"
> operator.

At the moment, one can use sublist() in order to pick-up a particular
item of a sequence. This makes an XPath 2.0 possible, but it seems ugly
and inefficient.

As David Carlisle pointed out to me, the omission of a subscripting
operator for sequences (one cannot use "$seq[$i]") from the language is
more of a bug than intentionally done. This was confirmed by Mike
sometimes ago, I think.


There has been a very nice reply from Mike Kay on the 
www-xpath-comments@xxxxxx list. It contains some ideas about the future
syntax of the function object, its type definition and typechecking and
also about anonymous functions. I'm still thinking on it and I think
responding to Mike's message (by me or anyone else) would not be a bad
thing, would it be, Mike?

Other people have contacted me and asked that I post my proposal also
to to the query list and xquery-comments.

I'd appreciate it to know if more people think this would be useful?

One person expressed disapproval of the fact that for the solutions I
used Haskell and not XSLT 1.0 generic templates. My reply to this is
that if I used generic templates, the text would have been 5 times
longer.

In case anybody needs the XSLT 1.0 version of the solutions, please,
let me know and I'll publish them on the list. In fact, I have the one
for the running total problem ready and running.

Cheers,
Dimitre Novatchev.


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