RE: Formal Semantics: fs:convert-operand() erroneous?

Thanks for the comment. 

Let me address your comments about XMark 11's validity.

The static rules for numeric operations expect ?. So your expression
below is a static error anyway.

You would have to write one of

(for $t in $i/text() return 5000 * $t)
(5000 * exact-one($i/text())
(5000 * zero-or-one($i/text())
(5000 * ($i/text())[1]

Depending on what you want the behaviour to be.

HTH
Michael

> -----Original Message-----
> From: public-qt-comments-request@w3.org [mailto:public-qt-comments-
> request@w3.org] On Behalf Of Jens Teubner
> Sent: Monday, August 23, 2004 8:20 AM
> To: public-qt-comments@w3.org
> Subject: Formal Semantics: fs:convert-operand() erroneous?
> 
> 
> Hi,
> 
> the latest XQuery Formal Semantics defines the fs:convert-operand()
> function in Section 6.1.3 [1].  In a nutshell, fs:convert-operand()
> casts its first argument to the type of a given sencond argument, if
it
> had been a subtype of xdt:untypedAtomic before.  Otherwise the first
> argument is returned unchanged.
> 
> The type of fs:convert-operand(), however, is defined as
> 
>  fs:convert-operand($actual as item *,
>                     $expected as xdt:anyAtomicType)
>      as xdt:anyAtomicType ?  .
> 
> Note that it allows an arbitrarily long sequence of items as its first
> argument.  The return value, however, is a sequence of at most length
> one.
> 
> The specifications only consider the case where $actual has a length
no
> longer than one.  So the return value for $actual being a longer
> sequence remains undefined.
> 
> fs:convert-operand() could easily be fixed by restricting $actual to
an
> optional item (item?).  This, however, would make queries such as
XMark
> 11 [2] illegal:
> 
> for $p in fn:doc("auction.xml")/site/people/person return
>   let $l :=
>     for $i in
> document("auction.xml")/site/open_auctions/open_auction/initial
>       where $p/profile/@income > (5000 * $i/text())
>       return $i
>     return
>       element items {
>         attribute name { $p/name/text() }
>         text { count ($l) }
>       }
> 
> Note the `5000 * $i/text()'.  $i/text() evaluates to node*.  The
Formal
> Semantics rule for Arithmetics [3] applies fn:data(), returning an
> xdt:untypedAtomic* on the non-validated document.  If the first
argument
> of fs:convert-operand() were restricted to item? it could not be
applied
> to `$i/text()', making the above query illegal.
> 
> Regards
> 
> Jens Teubner
> 
> [1] http://www.w3.org/TR/xquery-semantics/#sec_convert_operand
> [2] http://www.ins.cwi.nl/projects/xmark/Assets/xmlquery.txt
> [3] http://www.w3.org/TR/xquery-semantics/#sec_arithmetic
> 
> --
> Jens Teubner
> University of Konstanz, Department of Computer and Information Science
> D-78457 Konstanz, Germany
> Tel: +49 7531 88-4379     Fax: +49 7531 88-3577
> http://www.inf.uni-konstanz.de/~teubner
> 
> Statistics show that most people are in
> the majority, while a few are in the minority.
>                          -- Nitin Borwankar
>

Received on Monday, 23 August 2004 16:47:55 UTC