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Re: Lee's feature proposal

From: Kendall Clark <kendall@clarkparsia.com>
Date: Fri, 1 May 2009 11:35:51 -0400
Message-ID: <1fc9c2ff0905010835u280a2886n7251e90381316738@mail.gmail.com>
To: Lee Feigenbaum <lee@thefigtrees.net>
Cc: "Seaborne, Andy" <andy.seaborne@hp.com>, SPARQL Working Group <public-rdf-dawg@w3.org>
On Fri, May 1, 2009 at 10:30 AM, Lee Feigenbaum <lee@thefigtrees.net> wrote:

> As I've said repeatedly, I think the OPTIONAL/!bound construct is a major,
> major stumbling block to learning the language. I think it's just about the
> most important thing the WG can do from an educational point of view to fix
> that. (I personally ranked Negation 4th in my survey response). All of which
> is to say, you don't have to convince me of this.

Yes, but it seems someone needs to be convinced in order for us to
work on it. :>

> I'm happy to include it in the proposal, acknowledging that Andy is spot on
> that it's a list of features and not implementations. I mainly left it out
> since the number of features I was proposing was beginning to scare me vis a
> vis our timeline.

Again, fair enough, but we're roughly treating all the features as
equivalently substantive in terms of how much it will take to get them
specified, and I don't believe that's really true (nor does anyone
else, I should think). Also, negation just strikes me as something we
*have* to fix or we'll be embarrassed.

>> (Btw, all of this applies to assignment, too, for our integrity
>> constraint use cases.)
>
> Can you give an example / explain? Is this a use case that is satisfied by
> assignment but not by projected expressions + subqueries?

Whether you can get assignment & negation w/ project & subquery isn't
something I've thought about. However, my guess is that, even if you
can, it won't be as clear as assignment & negation, especially since
it may require more than one level of nesting, and that, IMO, starts
to get very ugly, very quickly. (We presently use Jena's LET, but have
a weak preference for assignment in SPARQL directly.)

I'm happy to be proved wrong since I would like to add the smallest
number of things to SPARQL that cover the most use cases, while making
queries generally clearer and comprehensible. If project+subq does
that, then great. But I'd be surprised. :>

Cheers,
Kendall
Received on Friday, 1 May 2009 15:36:51 GMT

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