- From: Olivier Corby <Olivier.Corby@sophia.inria.fr>
- Date: Mon, 21 Dec 2009 16:51:08 +0100
- To: Andy Seaborne <andy.seaborne@talis.com>, SPARQL Working Group <public-rdf-dawg@w3.org>
> 8 Negation - Testing for the absence of a pattern
>
> I am not really happy that the EXISTS and NOT EXISTS pattern can be used
> in a filter.
>
> Could you say why that is?
It is a feeling about language design.
Graph pattern is about graph match and filter is about evaluable
expressions. Here we mix both and that looks strange to me...
> Yes it can be combined with any other expressions. The effect of &&
> can be achieved anyway but not ||.
>
> FILTER( EXISTS {?x :tax :exempt} || ?taxCode = :special )
What about:
{EXISTS {?x :tax :exempt}} union { NOT EXISTS {?x :tax :exempt}
filter(?taxCode = :special) }
> The new variable is introduced using the keyword AS; it must not already
> be potentially bound.
> Do you have an suggestions for text changes?
May be we can list the places where the 'variable' cannot be used ?
Olivier
Received on Monday, 21 December 2009 15:51:43 UTC