ne of the workgroup is available to discuss those cases.
Thanks,
Wouter
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Lagua Web Solutions
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W.S. Hager
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1 to array:size($array))[ $array(.) = $value ]
> }
>
> which is hardly a great hardship to write as a user-defined function.
>
>
> Michael Kay
> Saxonica
>
> On 26 Jun 2015, at 12:18, W.S. Hager wrote:
>
> Hello,
>
> I've been working with the recent xquery 3.1 im
Correction: fn:index-of([1,2,[3,4]], 3)
2015-06-26 14:30 GMT+02:00 W.S. Hager :
> Hi Micheal,
>
> Agreed, it could be implemented as a user-defined function (although this
> particular solution currently throws an error in eXist). However, what
> bothers me is that fn:index-of(1,
ction to do.
>>
>> If it’s to behave like fn:index-of() then you can write it as
>>
>> array:index-of($array, $value) {
>>(1 to array:size($array))[ $array(.) = $value ]
>> }
>>
>> which is hardly a great hardship to write as a user-defined function.
&
Ignore my last sentence, I don't want to make this claim.
2015-06-26 16:38 GMT+02:00 W.S. Hager :
> On the whole I agree, and I respect the current status quo of the
> specification. However, I expect more changes will follow from actually
> working with it. IMHO the current disti
[[a]] from [a]. So we have arrays that
> allow nesting, and sequences where singletons are the same as items, and
> the two models are irreconcilable.
>
> Michael Kay
> Saxonica
>
>
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W.S. Hager
Lagua Web Solutions
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Hi Christian,
2015-06-26 17:18 GMT+02:00 Christian Grün :
>
>
> Too late ;)
>
>
Heh. I should have thought before posting, as it was merely a vague
intuition. The problem is of course backwards compatibility, as Michael
mentioned.
As an aside, does anyone know what the formal definition of sequ
Sorry, what I meant is: how did sequences come into XPath? Was it borrowed
from another system or did it appear first in XPath?
2015-06-26 17:29 GMT+02:00 G. Ken Holman :
> At 2015-06-26 17:23 +0200, W.S. Hager wrote:
>
>> As an aside, does anyone know what the formal definition of
Indeed! Thanks David.
2015-06-26 17:52 GMT+02:00 David Carlisle :
> On 26/06/2015 16:33, W.S. Hager wrote:
>
>> Sorry, what I meant is: how did sequences come into XPath? Was it
>> borrowed from another system or did it appear first in XPath?
>>
>
> It's a mo
ced by both functional
> programming AND databases, was also Michael Rys (Microsoft).
>
> He was also fundamental in this decision, and many other afterwards.
>
> HTH,
> Dana
>
>
>
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arser was written by me and James
> (both bitching about the “features” in other’s side..:-)
>
> But overall, I think XSLT and XQuery ended up integrated pretty nicely, so
> it was worth the effort.
>
> Best regards
> Dana
>
>
>
>
>
>
I meant *the lack of* array:index-of(), obviously.
2015-06-26 19:32 GMT+02:00 W.S. Hager :
> That should provide some positive perspectives for integrating with the
> web... wait, did I just get off-topic? Oops? No. I write a great deal of
> javascript, and this is actually why I woul
ML.
>
> JSON and Javascript are not that….unfortunately.
>
> XML and JSON communities are like water and oil….
>
> So, who would like to be considered BY !??
>
> (I wish I knew the answer to that question …)
>
> Best regards
> Dana
>
>
>
>
>
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W.S. Hager
Lagua Web Solutions
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Perhaps I should underline that I don't find these "inconsistencies" very
problematic. It's not javascript, and the language has been spectacularly
enriched by these function types. I'm sure it'll be fine without the
conviences I suggested.
Thanks.
2015-06-26 23:3
dy been motivated and
> discussed in the group before.
>
> Talking about conditions: An if expression without 'else' branch would
> often be nice as well (if not present, an empty sequence could be
> returned).
>
>
> > On 26 June 2015 at 12:18, W.S. Hager wro
One more consideration: function calls seem to be more expensive than
inline expressions. And then there's that baggage of a custom library...
2015-06-28 14:35 GMT+02:00 W.S. Hager :
> Hmm, I'm not so sure. The if/else clause is pretty short as it is, and
> semantically more
Sorry, I didn't mention I was thinking about the case where I would create
a library module instead of using inline functions.
2015-06-28 21:01 GMT+02:00 Michael Kay :
>
> > On 28 Jun 2015, at 19:32, W.S. Hager wrote:
> >
> > One more consideration: function calls seem
Hi,
Why is it "import module" and not "import"? Can something other then a
module be imported?
Thanks,
Wouter
--
W.S. Hager
Lagua Web Solutions
http://lagua.nl
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Ah, I found it: import schema. Nevermind.
2015-11-13 11:45 GMT+01:00 W.S. Hager :
> Hi,
>
> Why is it "import module" and not "import"? Can something other then a
> module be imported?
>
> Thanks,
> Wouter
>
> --
>
> W.S. Hager
> Lagua We
Hi,
Perhaps this is not the place to discuss this, but I was quite surprised
when I stumbled upon the current DOM level 4 spec, which deprecates 4 node
types in respect to XML DOM.
Are these changes expected to affect XML DOM implementations?
Thanks.
--
W.S. Hager
Lagua Web Solutions
http
Thanks.
2015-12-01 16:50 GMT+01:00 Michael Kay :
>
> > On 1 Dec 2015, at 13:32, W.S. Hager wrote:
> >
> > Hi,
> >
> > Perhaps this is not the place to discuss this
>
> Indeed. I can't see any particular relevance to XQuery.
>
>
> > , but I
g.uk
> ___________
> talk@x-query.com
> http://x-query.com/mailman/listinfo/talk
>
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etter :
> Any chance you could offer me an example? ;-)
>
> On 26 January 2016 at 16:40, W.S. Hager wrote:
> > Hi Adam,
> >
> > Perhaps it helps to start with rewriting the xpath expressions as pure
> > lambda expressions. Maybe that way you could apply lambda calculus?
&
Hi Adam,
I'm looking at the formal specification of xpath/xquery:
http://www.w3.org/TR/xquery-semantics
It would really help to start with a function that implements the actual
selection in steps. Do you know such a function?
Thanks,
Wouter
Op dinsdag 26 januari 2016 heeft W.S. Hager
Here's the entry on steps:
http://www.w3.org/TR/xquery-semantics/#id-axis-steps
I missed it before. To be continued I guess. I'd love the idea of a sound
formal proof.
Op dinsdag 26 januari 2016 heeft W.S. Hager het
volgende geschreven:
> Hi Adam,
>
> I'm looking at
ong
> run, and enables them to get papers published in the academic literature,
> it is totally useless to practical engineeers who want to know whether they
> can safely rely on C.
>
> Michael Kay
> Saxonica
>
>
>
>
--
W.S. Hager
Lagua Web Solutions
http://lagua.nl
esults that automatically hold
> for the full specification, even though they are
> proved on a clean and easy-to-use subset: undecidability and
> np-completeness or np-hardness for instance.
>
> For the full specifications its sometimes hard to grasp the semantics, so
> proving anything seri
Isn't the constraint in this case the test: is p2 a subset of p1?
2016-01-27 11:04 GMT+01:00 Pavel Velikhov :
>
> > On 27 Jan 2016, at 12:54, W.S. Hager wrote:
> >
> > Can't we formally proof something as obvious Adam's case?
>
> In Adam’s case
Or simplified: is the set selected by p1 equal to the set selected by p2?
2016-01-27 11:09 GMT+01:00 W.S. Hager :
> Isn't the constraint in this case the test: is p2 a subset of p1?
>
> 2016-01-27 11:04 GMT+01:00 Pavel Velikhov :
>
>>
>> > On 27 Jan 2
e the halting problem of Turing machines to this test.
>
>
> 2016-01-27 11:09 GMT+01:00 W.S. Hager :
>
>> Isn't the constraint in this case the test: is p2 a subset of p1?
>>
>> 2016-01-27 11:04 GMT+01:00 Pavel Velikhov :
>>
>>>
>>>
gt;
>>
>>
>> Or simplified: is the set selected by p1 equal to the set selected by p2?
>>
>>
>> If we allow p1 and p2 to be arbitrary XQuery path expressions, then its
>> undecidable.
>> I can reduce the halting problem of Turing machines to this test.
XQuery expression language is Turing complete
> 3. Subsumption for a Turing complete language is undecidable.
>
> Well, I can hardly see a way to decide this problem other then by
> introducing SOME restrictions
> of some sort… but of course some restrictions that would not nullify th
gt; 2. XQuery expression language is Turing complete
> >> 3. Subsumption for a Turing complete language is undecidable.
> >>
> >> Well, I can hardly see a way to decide this problem other then by
> >> introducing SOME restrictions
> >> of some sort…
mitations)?
>
> Yes.
>
> > Or just that one case?
>
> No I want to cover any case where the set which would be selected by
> the path expression is statically known (i.e. no function calls).
>
>
>
> --
> Adam Retter
>
> skype: adam.retter
> tweet: adamr
nuari 2016 heeft Pavel Velikhov
het volgende geschreven:
> Hmm.. testing subsumption is not as trivial as I thought. Here's a cleaner
> way to do it: represent both path expressions as DFAs and then test
> subsumption. You'll get DFAs A and B and then test if minimized(B-A) is
iry.
>
>
> On 29 Jan 2016, at 20:53, W.S. Hager wrote:
>
> This is the best I (actually Google) can do.
>
> Proof:
> https://coq.inria.fr/library/Coq.MSets.MSetGenTree.html
>
> Test:
>
>
> http://www.geeksforgeeks.org/check-if-a-binary-tree-is-subtree-of-an
Hello,
What is the difference between a function declaration and a function
expression in a variable declaration, eg:
declare variable $local:id := function($x) { $x }
and why does it exist?
--
W.S. Hager
Lagua Web Solutions
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of a
> variable at runtime, however, you will need to use inline function
> expressions. Variables in scope will be added to the closure of the
> created function item.
>
> I hope it helps!
>
> Kind regards,
> Ghislain
>
> On Mon, Mar 14, 2016 at 2:48 PM, W.S. Hager &
I just love to do .[1][1][1][1][1][1][1]
Op 31 okt. 2016 19:19 schreef "Michael Kay" :
> I agree with the other respondents: apart from giving an error if the
> context item is not a node, "./." is precisely equivalent to ".".
>
> (Not sure why an XSLT question is appearing on the XQuery list...)
Hello,
Not sure if anyone already noticed, but there's an error in the
XPath/XQuery F&O docs, where the example implementation of array:fold will
always return an array...
More importantly, it seems to me that a textbook implementation of
fold-right was used, without the notice that this will onl
Hello Michael,
2017-01-12 14:09 GMT+01:00 Michael Kay :
> Logged here as a bug:
>
> https://www.w3.org/Bugs/Public/show_bug.cgi?id=30045
Thanks, will do it next time.
No, I think the subsequent points are far less important. The code used to
> specify the effect of the function is intended to
why it's preferable
> to have a syntax without an implementation, and I simply pointed out that
> in the case of the fold-right example that becomes slightly odd...
>
>
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Better still, remove fold-right entirely, since laziness isn't part of the
spec (specifically infinite lists).
2017-01-12 18:10 GMT+01:00 W.S. Hager :
> Can we please agree to add a footnote to the fold-right example that says
> something along the lines of "this example
Hi Joe,
In addition to other comments: also the size of the data matters, and not
to mention the purpose of what you're trying to achieve... Small chunks are
usually processed faster, so unless you just need to convert all data,
perhaps limiting the set could be useful. Especially when you need ye
Fact of the matter is that if a low level optimization can be made, it must
be made outside of XQuery. I assume it happens all the time. But sure, it
depends on the use case.
Op 15 jul. 2017 22:47 schreef "Michael Kay" :
>
> Obviously this operation could be implemented in the host language to
ma
an C).
Did you come across particular use cases in which it turned out that
XQuery maps and arrays were not the best choice? What do you believe
was the critical factor (memory consumption, runtime, …)?
Cheers,
Christian
On Sun, Jul 16, 2017 at 12:08 PM, W.S. Hager wrote:
> Fact of the matter
What I meant is that the cost of immutability can be avoided in some cases.
That's primarily a matter of low level short-circuiting, not so much of
writing something new. I don't know if this can be done in Java, I know the
Clojure compiler does this, and I'm not aware of XQ engines that do
transie
Hi,
Is there any advantage to using the 3.1 arrow operator over the simple map
operator?
$string => upper-case() => normalize-unicode() => tokenize("\s+")
versus
$string ! upper-case(.) ! normalize-unicode(.) ! tokenize(.,"\s+")
Thanks,
Wouter
___
ta
; changes the context item, so
@address => replace(@postcode, "", "q") works, while
@address ! replace(@postcode, "", "q") doesn't.
Michael Kay
Saxonica
> On 1 Aug 2017, at 13:27, W.S. Hager wrote:
>
> Hi,
>
> Is there any advantage
tem :)
> > @address ! string() (: context item passed implicitly to string#0, which
> is context-dependent)
> > @address => string() (: context item passed implicitly to string#1 via
> the => operator, but string#1 is context-independent)
> >
> > I hope I got it right!
That's why, for cases where it's possible, I preferred to write the simple
mapping operator, as it's easier to read IMO.
2017-08-02 12:07 GMT+02:00 W.S. Hager :
> Hi Ghislain,
>
> Alright, I forgot about fn:replace#4, but the implicit binding is
> sometimes hard to det
y => array:remove($position) => array:insert-before($position,
> $member)
>
> Kind regards,
> Ghislain
>
> [1] https://www.w3.org/TR/xpath-functions-31/
>
>
> > On 2 Aug 2017, at 12:09, W.S. Hager wrote:
> >
> > That's why, for cases where it&
To be precise, I think it means that the context needs to be bound to the
result of the left side of the arrow, but perhaps that isn't even possible.
Anyway, the convention seems to me just as trivial as binding the first
argument.
2017-08-02 16:17 GMT+02:00 W.S. Hager :
> Dear
Why can't the context contain a sequence?
2017-08-02 16:31 GMT+02:00 Ghislain Fourny :
> Dear Wouter,
>
> I see your point and it makes sense. The tricky part here, following up on
> your suggestion to make the choice of the first position less arbitrary, is
> that the context item must be an it
Hi Michael,
Anonymous functions would've been quite nice, but could your example only
be used for a single argument?
Op 2 aug. 2017 17:44 schreef "Michael Kay" :
>
> To put things in perspective, => was introduced in version 3.1, together
with map and array support. As far as I understand it and
I see, thanks.
Op 3 aug. 2017 23:01 schreef "Michael Kay" :
> >
> > Anonymous functions would've been quite nice, but could your example
> only be used for a single argument?
>
> Yes. I think that's such a common case that it's worth having special
> syntax for, particularly as we already have ".
Hi all,
Please note that all your replies landed in spam...
Op 4 mrt. 2018 16:26 schreef "Joe Wicentowski" :
> Hi all,
>
> Thanks for these links! I've adapted many of these into the Learn XQuery
> list that I maintain:
>
> https://github.com/joewiz/learn-xquery
>
> From the description: "A l
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