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   Re: [xml-dev] XQuery types was Re: [xml-dev] Yet another plea for XUpdat

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> At 12:57 PM 5/6/2002 -0600, Uche Ogbuji wrote:
> > > If you think Bertrand Meyer is on the right track, saying that both 
> > dynamic
> > > typing and static typing are important, then why do you think that this
> > > does not apply to XQuery?
> >
> >Because Meyer was constructing a compiler: he had to deal directly with 
> >the physical layer.  I think one of the strengths of XML is that 
> >technologies at the XML layer should not have to.  This was also one of 
> >the promises of relational DBMS, which I think got besmirched in the 
> >ascendancy of SQL.
> We agree that an XML query language should not be closely wed to a physical 
> representation. But types are not an attribute of the physical layer, and I 
> don't understand how strong static typing weds an XQuery implementation to 
> any particular physical strategy. Can you go into more detail on this?
> The strong static typing may tell me, for instance, that a query is invalid 
> because you can't multiply an integer times a URL, or because a query will 
> raise errors if an optional element is omitted in a dataset. What does this 
> have to do with the physical storage of the data being queried?

Ah.  This does tell me it was a good thing I made my follow-up post.  I expect that will clear things up for you.  XQuery is not an explicit target of my static typing complaint.  I did comment that I would rather have a dynamic capacity for constraint checking (and triggers based on constraints), but that was a broad and unmeasured swipe.  In order to give a keen critique of the static typing used in the XQuery formal semantics I'd have to first read it.  I might yet do, given JB's and JJC's interesting comments on the matter, but probably not right away.

Uche Ogbuji                                    Fourthought, Inc.
http://uche.ogbuji.net    http://4Suite.org    http://fourthought.com
Track chair, XML/Web Services One (San Jose, Boston): http://www.xmlconference.com/
DAML Reference - http://www.xml.com/pub/a/2002/05/01/damlref.html
RDF Query using Versa - http://www-106.ibm.com/developerworks/xml/library/x-think10/index.html
XML, The Model Driven Architecture, and RDF @ XML Europe - http://www.xmleurope.com/2002/kttrack.asp#themodel


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