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

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Uche Ogbuji wrote:

> I think this is all an unfortunate misunderstanding.
> Jonathan, Dare and I were talking about static types (I also use the term
"imperative types") in our discussion before XQuery formal semantics were
brought up.  I dropped out of the discussion at that point because I have
not read this document, but I think it's reasonable to assume that Dare was
continuing to talk about static types when he said "types".  This is a very
common abbreviation among programmers (though I wish it weren't), and you
yourself later on admitted you probably understood Dare as such.  It's also
useful to remember that the use of the word "class" in object oriented
development is very different from its more general use.

Yes I see, however when "type" or "class" is used in the context of a
"formal semantics" there is no notion of "compile time type checking" vs.
"run time checking" (a.k.a. schema validation).

In any case let's not continue the misunderstanding -- though clearing this
up _is_ useful.

> 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.
> Also, I explore a bit of this in one of my Thinking XML column
installments.  I purposefully use lay/programmer language in it because the
column is specifically billed as being for programmers, not philosophers.
> http://www-106.ibm.com/developerworks/xml/library/x-think8.html

Well written.

As an aside, I have come to the understanding that way RDF allows the
"rdf:type" property to be derived via subPropertyOf e.g. your
"vcard:contactType" causes hairy problems for lots of classification
software (and we realize that there actually is software out in production
which can do real things with classifications, e.g. CLASSIC, FaCT etc.)



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