[xquery-talk] type of 1.2 div 1.2?

[Michael Kay]

I think that fs:untyped-to-double is a no-op if the argument isn't
untypedAtomic, just as fn:data() is a no-op if the argument is atomic.

Remember that Galax is following the formal semantics very literally,
regardless of efficiency.

Michael Kay 

> -----Original Message-----
> From: Howard Katz [mailto:howardk at fatdog.com] 
> Sent: 23 March 2005 00:51
> To: Michael Kay; talk at xquery.com
> Subject: RE: [xquery-talk] type of 1.2 div 1.2?
> 
> Oops, mea culpa. I misread something. I'm looking at galax, 
> and typeswitch
> shows that the final result is actually decimal as it should 
> be. What threw
> me was an intermediate result, which shows the normalized core
> representation for this query as:
> 
>   op:numeric-divide(
>   fs:untyped-to-double(fn:data(1.2)),
>   fs:untyped-to-double(fn:data(1.2))
> 
> Given this, I still don't understand:
> 
> (1) why there's an untyped-to-double conversion, since I 
> would have thought
> the grammar provided the typing information on the numerics as decimal
> literals,
> and
> (2) even if there are intermediate doubles, how we get from 
> there to a final
> decimal result?
> 
> Howard
> 
>  > -----Original Message-----
>  > From: talk-bounces at xquery.com 
> [mailto:talk-bounces at xquery.com]On Behalf
>  > Of Michael Kay
>  > Sent: Tuesday, March 22, 2005 12:30 PM
>  > To: howardk at fatdog.com; talk at xquery.com
>  > Subject: RE: [xquery-talk] type of 1.2 div 1.2?
> 
>  >
>  > The result should definitely be of type xs:decimal.
>  >
>  > There's some debate about whether it's permissible to 
> return a subtype of
>  > xs:decimal, e.g. xs:integer or my:veryShortInteger; but
>  > returning xs:double
>  > is not on.
>  >
>  > (Unless this is actually an XPath processor with 1.0 
> compatibility mode
>  > enabled).
>  >
>  > Michael Kay
>  > http://www.saxonica.com/
>  >
>  >
>  > > -----Original Message-----
>  > > From: talk-bounces at xquery.com
>  > > [mailto:talk-bounces at xquery.com] On Behalf Of Howard Katz
>  > > Sent: 22 March 2005 18:44
>  > > To: talk at xquery.com
>  > > Subject: [xquery-talk] type of 1.2 div 1.2?
>  > >
>  > > What's the type and value of the single atomic returned 
> by the query:
>  > >
>  > >      1.2 div 1.2
>  > >
>  > > I'm looking at different implementations. I see one returning an
>  > > xsd:decimal, value 1 as a result (my understanding as well).
>  > > I see another
>  > > treating the data as untyped and doing two conversions to
>  > > xsd:double first,
>  > > again returning a value of 1 but this time of type xsd:double.
>  > >
>  > > Which one is correct?
>  > > Howard
>  > >
>  > >
>  > >
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>  > >
>  >
>  >
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> 
> 
>