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

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> At 12:07 PM 5/5/2002 -0600, Uche Ogbuji wrote:
> >Anyway, back to the main point.  I agree with your broader definition of 
> >types as being defined by constraints, and this is *precisely* why I am 
> >always ridiculing the W3C efforts which put so much effort into static 
> >typing at the behest of their SQL and procedural programming backgrounds 
> >(I guess).  Programmers don't need to become pure mathematicians to 
> >appreciate this: Bertrand Meyer provides much of the essence in his own 
> >writing about object-oriented development.
> I don't really understand you here, Uche.

Of course you don't.  Because I assumed we were talking about utility for XML, not general purpose programming, I ommitted  the 25 pages it requires to discuss the philosophy behind first-class dynamic typing without ambiguity.


> Bertrand Meyer certainly felt that static typing was a central feature of 
> Eiffel, the language he designed.

Static typing was there, for the same reason that static typing emerged in compilers in the first place: to take advantage of physical layer facilities provided by the hardware.  I am not arguing this reality, and never have.  My problem with static typing starts when it becomes the basis of user data typing in languages.  For instance, the C++ and Java wedding of static types to classes, causing painful distortion to both.

When it comes to user modularization, Meyer favors general-purpose constraints, which is why he built *these* into Eiffel.

Static typing is a necessary evil for systems at that lower level: for performance reasons.  Being that XML is at a higher level of processing, it should not have to be bound to this evil.  At least not explicitly.

> 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.

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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