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Re: Proposal to drop disjunction requirement

From: Kendall Clark <kendall@monkeyfist.com>
Date: Thu, 30 Sep 2004 09:06:24 -0400
To: DAWG public list <public-rdf-dawg@w3.org>
Message-ID: <20040930130624.GE25264@monkeyfist.com>

On Thu, Sep 30, 2004 at 02:01:50PM +0100, Steve Harris wrote:
> 
> In order to close the disjunction issue, I propose that we drop any
> requirement for graph disjunction in this version of the query language.

I don't presently support such a proposal, but I might be persuaded
to...

> OR is the only infix operator we have prposed so far, so it complicates
> the syntax from the point of view of learning it, and makes the precidence
> rules more complex and requires logical ()'s to scope expressions.

I see these differently: (1) the learning cost is negligible, IMO; (2)
the implementation burdens are mostly one-time and only for a few
people. And I'm not convince they're that onerous anyway.

> Disjuntion provides a lot of the same capability as optional matches, but
> as a developer I've only seen feature reqests expressed in terms of
> optional match, no disjunction. Many disjunctive queries can be expressed
> in terms of optionals and value disjunctions, but I have not attempted to
> show wether all can be or not.

What would seal the deal for me is a more detailed argument that
optionals and value disjunctions really do handle all (or nearly all)
disjunction uses. That is, I want to know which disjunction cases
*aren't* covered before I support removing it from the language. I
want to know what I'm giving up, in other words, before I give it up.

> Getting good coverage for test cases will be hard. Esspecially in
> combination with optional it allows you to write some really complex
> expressions. Testing all combinations will be difficult.

Again, that's a fair point, but doesn't persuade me by itself.

Best,
Kendall
Received on Thursday, 30 September 2004 13:08:57 GMT

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