[xquery-talk] Is it possible to maintain a list of value in XQuery

Liam R E Quin liam at w3.org
Wed May 15 16:25:25 PDT 2013

On Wed, 2013-05-15 at 23:10 +0000, David Lee wrote:
> I boldly propose that perhaps as a group we step back and get off our
> high horse and admit that some procedural  aspects to XML processing
> be embraced instead of hidden in the dark corners of "vendor
> implementations"  that every single vendor has had to provide because
> pure functional programming  has simply not lived up to its promise.

I don't think it's about a high horse. The XQuery WG spent multiple
years trying to wrestle with adding procedural hooks to XQuery. Part of
the difficulty was that it was a group of people who did not share a
common goal. For example, some people thought it would be nice to offer
a sort of bait-and-switch language where the easy stuff was procedural
but anything hard was functional, a sort of gentle slope learning curve
followed by a cliff, instead of a very steep hill at the start. Others
needed synchronization and orchestration.

My own feeling is still that the scripting extensions would work better
as a framework rather like XProc, orchestrating functional chunks of
XQuery (and/or XSLT) at a higher level, with clearly-defined boundaries
for optimization & transactions. One problem with them as written today
is that it's easy to put a semicolon instead of a comma in places where
it's still legal, but has a different meaning, one which has the
side-effect (!) of effectively disabling a lot of optimization.

At any rate we ended up delaying XQuery 3 for a year or more while
working on the scripting extensions, without really coming to a good

Maybe the long term answer is XQuery extensions to JavaScript.


Liam Quin - XML Activity Lead, W3C, http://www.w3.org/People/Quin/
Pictures from old books: http://fromoldbooks.org/
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