Christian,
This is easy to find in the spec ... if you look at the right spec. :-)
http://www.w3.org/TR/xpath-datamodel/#sequences
Cheers, Wendell
On Mon, Apr 7, 2014 at 8:31 PM, Christian Roth <roth(_at_)visualclick(_dot_)de>
wrote:
Hi,
why is
(1) cast as xs:integer == 1
Or is it?
I hit upon this while trying to understand why this works:
subsequence( ('a','b'), (1), 1)
subsequence() expects an xs:double as its second parameter, but not a
single-item _sequence_ of xs:double's. Because it works, "(1) cast as
xs:double" must be equivalent to "1 cast as xs:double", and therefore "(1) =
1".
Why I got that much confused is my following thinking on the description of
"cast" at <http://www.w3.org/TR/xpath20/#id-cast>.
It says:
1. Atomization is performed on the input expression.
With fn:data( (1) ) returning the sequence of atomized values of each of its
input sequence's members, this IMO yields (1).
2. If the result of atomization is a sequence of more than one atomic value…
Does not apply.
3. If the result of atomization is an empty sequence: …
Does not apply.
4. If the result of atomization is a single atomic value…
Also does not apply in my thinking, as I get a _sequence_ of a single atomic
value. There's no step that tackles the case where the result of atomization
is a sequence of a single atomic value.
Therefore, I guess that a single-atomic-valued-item sequence is the same (or
equivalent?) as its single atomic member. I vaguely remember reading that
long time ago somewhere in the spec, but cannot find it now. Can someone
please point me to the relevant section? Thanks!
Regards
Christian
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