[xquery-talk] arrow operator

Ghislain Fourny gfourny at inf.ethz.ch
Wed Aug 2 06:56:29 PDT 2017


Dear Christian,

I agree; Actually, as far as I recollect, in the initial draft for the ! operator, I had spontaneously given it the same precedence as / in the grammar. We later decided that it made sense to keep them strictly separate as it makes the semantics much clearer, especially regarding sorting and duplicate elimination.

Kind regards,
Ghislain


On 2 Aug 2017, at 13:10, Christian Grün <christian.gruen at gmail.com<mailto:christian.gruen at gmail.com>> wrote:

As Ghislain indicated, the semantics of the two operators differs
pretty much (although there are surely some cases in which they can
serve as equivalent alternatives). Actually, the mapping operator is
much closer to XPath steps. There are even good reasons for replacing
/ with !, e.g. if you do not want to have duplicate-free and ordered
results.

Christian

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