[Monetdb-developers] XQuery type casts: "X cast as xs:TYPE" vs. "xs:TYPE(X)"

Jens Teubner jens.teubner at in.tum.de
Wed Aug 16 17:13:06 CEST 2006

On Wed, Aug 16, 2006 at 10:30:34AM +0200, Stefan Manegold wrote:

> Hi Pathfinders,
> W3C's XML Query Test Suite (XQTS) makes excessive use of type casts a la
> 	xs:TYPE(X)
> Pathfinder, however, doesn't like this, complaining about
> 	reference to undefined function `xs:TYPE'
> [...]
> Instead, Pathfinder seem to prefer type casts a la
> 	X cast as xs:TYPE
> What's the desired solution to solve this problem?
> Implement also "xs:TYPE(X)" in Pathfinder?
> Or "customize" all XQTS tests to use 
> "X cast as xs:TYPE" instead of "xs:TYPE(X)"?

In XQuery speak, the operators of the form

  xs:TYPE( ... )

are referred to as ``constructor functions'' (not casts).  They do have
the same semantics as the respective `cast as' clauses.

In my opinion, the "desired solution" is to implement the xs:TYPE()
constructors in Pathfinder and not patch the XQTS tests again.  We can
hardly claim to be compliant if we need to patch the majority of the
tests in advance.

I am not an expert in milprint_summer.  Any volunteers?


Jens Teubner
Technische Universitaet Muenchen, Department of Informatics
D-85748 Garching, Germany
Tel: +49 89 289-17259     Fax: +49 89 289-17263

There are 10 types of people in the world;
those who understand binary, and those who don't.

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