[xquery-talk] xquery 3.1 wishlist

[W.S. Hager]

Ignore my last sentence, I don't want to make this claim.

2015-06-26 16:38 GMT+02:00 W.S. Hager <wshager at gmail.com>:

> 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
>



-- 

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