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[Bug 3273] [FS] technical: 2.3.1 Formal values: () in Values

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Date: Mon, 05 Jun 2006 21:41:52 +0000
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http://www.w3.org/Bugs/Public/show_bug.cgi?id=3273





------- Comment #1 from simeon@us.ibm.com  2006-06-05 21:41 -------
Michael,

The ability to use the empty sequence (resp. the empty type) for values (resp.
types). Is intentional.

For values, the values follows the same rules as the corresponding sequence
constructors in XQuery. so (),((),1,()),2 = 1,2. I believe there used to be a
sentence about that in the formal values section.

For types, there are many expressions which generate sequences or unions of
empty types. (e.g., if Expr then () else 1). Fortunately all those types are
equivalent ((), xs:integer = xs:integer ; () | xs:integer = xs:integer?, etc.).
That is covered by the subtyping/equivalence rules in 8.3.2 Subtyping (<:).

So I believe this may be editorial, although I'm not sure what you think would
help clarify. I would recommend at least to add the sentence about values
(explaining the first part above)

Best,
- Jerome
Received on Monday, 5 June 2006 21:42:01 UTC

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