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[Bug 29628] 16.2.1 fn:for-each - proposal of more succinct rules

From: <bugzilla@jessica.w3.org>
Date: Wed, 25 May 2016 11:30:22 +0000
To: public-qt-comments@w3.org
Message-ID: <bug-29628-523-lipepbvZ7q@http.www.w3.org/Bugs/Public/>

--- Comment #5 from Hans-Juergen Rennau <hrennau@yahoo.de> ---
(In reply to Michael Kay from comment #2)
> I'm a bit reluctant to define fn:for-each in terms of "!" because the
> current definition of "!" is itself very informal. Our normal approach is to
> define operators in terms of functions, rather than the other way around. We
> currently do this only for first-order operators such as "+" and "=", but
> now we have higher-order functions it would make sense to define
> higher-order operators like "!" in terms of higher-order functions like
> fn:for-each.

Of course I accept the decision not to take actions, for the reasons given.

But one remark in reply to the general approach of defining operators in terms
of functions, and not the other way around, a remark which seemed to play a
role in the decision.

I think the semantics of the map operator (!) and the path operator (/) cannot
be defined in terms of an XQuery function, because the operator semantics
involve a resetting of the inner focus. For these reasons, I think the map and
the path operators are like "semantic atoms" (or axioms) and cannot be
translated into the semantics of a function, and for this reason they might
perhaps (?) legitimately be used in order to define the semantics of functions
(like fn:for-each).

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Received on Wednesday, 25 May 2016 11:30:26 UTC

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