[xquery-talk] xquery 3.1 wishlist

[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 distinction between sequences and arrays
could eventually be abolished.

2015-06-26 16:21 GMT+02:00 Michael Kay <mike at saxonica.com>:

>
>
> 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(1,2,[3,4], 3) may lead to unexpected
> results, because the array is flattened. I get the impression that
> array-specific semantics are sacrificed here, where in other cases they
> aren't, and the dividing line is still unclear me.
>
>
> Arrays will give unexpected results, full stop. We spent two years trying
> to find a design that didn’t have unexpected results, and we failed. Start
> with the fact that $A[1] returns the whole array, and that you can’t
> iterate over arrays with FLWOR expressions. Arrays are grafted on to the
> data model as an afterthought, and it shows right through. That’s not for
> want of trying: we were running out of names for all the different ideas we
> rejected as unworkable.
>
> The choice of functions in the library is inevitably arbitrary. I think we
> found that if you wanted a completely minimalist approach, everything could
> be defined in terms of three functions. At the other extreme you would have
> the functx approach, a thousand functions to do everything you could ever
> imagine, but where it’s quicker to write the function yourself than to find
> it in the library.
>
> Michael Kay
> Saxonica
>
>
> Thanks,
> Wouter
>
> 2015-06-26 14:16 GMT+02:00 Michael Kay <mike at saxonica.com>:
>
>> I would think both of these could be implemented as user-defined
>> functions but it’s hard to know without seeing a specification: saying you
>> want a function called array:index-of() is not very informative unless you
>> explain exactly what you want the function to do.
>>
>> If it’s to behave like fn:index-of() then you can write it as
>>
>> array:index-of($array, $value) {
>>    (1 to array:size($array))[ $array(.) = $value ]
>> }
>>
>> which is hardly a great hardship to write as a user-defined function.
>>
>>
>> Michael Kay
>> Saxonica
>>
>> On 26 Jun 2015, at 12:18, W.S. Hager <wshager at gmail.com> wrote:
>>
>> Hello,
>>
>> I've been working with the recent xquery 3.1 implementation in the
>> develop branch eXist-db. I encountered some cases that were quite hard to
>> work around:
>>
>> - the lack of array:index-of()
>> - the lack of the iterator index in arrayfor-each and related
>> higher-order functions
>>
>> Perhaps someone of the workgroup is available to discuss those cases.
>>
>> Thanks,
>> Wouter
>> --
>>
>> W.S. Hager
>> Lagua Web Solutions
>> http://lagua.nl
>>
>>
>> --
>>
>> W.S. Hager
>> Lagua Web Solutions
>> http://lagua.nl
>>
>> _______________________________________________
>> talk at x-query.com
>> http://x-query.com/mailman/listinfo/talk
>>
>>
>>
>
>
> --
>
> W.S. Hager
> Lagua Web Solutions
> http://lagua.nl
>
>
>


-- 

W.S. Hager
Lagua Web Solutions
http://lagua.nl
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