Re: Proposal to close ISSUE-76 stating that execution order matters

On 7/29/2015 9:02, Peter F. Patel-Schneider wrote:
> I would say instead that the *most relevant* computer languages, e.g., SQL and
> SPARQL, do not work this way.  I believe that most users of SHACL will not see
> that the connection to programming languages is so strong as to dictate how
> SHACL works.
>
> In general, users cannot tell which constraint is most restrictive.

In many cases they can. Why else do languages like SPARQL have ( ... ) 
brackets to control the execution order. According to your logic, those 
should be removed from SPARQL too.

Frankly, I believe the whole point of opening this ticket was to try to 
make it as hard as possible for us to make recursion work - the 
execution order is needed for error handling there. I would prefer an 
honest discussion instead of hiding behind pseudo arguments.

Thanks,
Holger


>    This is a
> job better done by the analog of query optimizers.  Requiring a particular
> order of evaluation will inhibit such optimiizations.
>
> peter
>
>
> On 07/27/2015 05:27 PM, Holger Knublauch wrote:
>> ISSUE-76 [1] is about whether the order of AND and OR operands should matter.
>> I believe the order should matter, because this is how most computer languages
>> work and therefore matches the expectation that users can put the most
>> restrictive operands first to avoid unnecessary evaluations. It also helps
>> produce consistent results in the face of errors. sh:AndConstraint and
>> sh:OrConstraint use rdf:Lists for that reason.
>>
>> Holger
>>
>> [1] http://www.w3.org/2014/data-shapes/track/issues/76
>>

Received on Tuesday, 28 July 2015 23:19:11 UTC