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RE: Syntax modifications

From: Seaborne, Andy <andy.seaborne@hp.com>
Date: Tue, 31 Aug 2004 11:51:57 +0100
Message-ID: <E864E95CB35C1C46B72FEA0626A2E80803E3C118@0-mail-br1.hpl.hp.com>
To: Alberto Reggiori <alberto@asemantics.com>
Cc: public-rdf-dawg@w3.org

> yes it makes sense - but I then do not understand why we need to make
> the syntax so much N3 like, using PREFIX and use :prefix notation
> instead of current RDQL USING prefix FOR <URI>

RDQL syntax can't handle the default prefix.

	Andy

-------- Original Message --------
> From: Alberto Reggiori <>
> Date: 30 August 2004 16:33
> 
> Andy, thanks for the clarifications - some short replies inline below...
> 
> On Aug 27, 2004, at 4:47 PM, Seaborne, Andy wrote:
> > 
> > There are a number of reasons behind the proposal: none of these is a
> > single reason to go one way of another.
> > 
> > 1/ We do need some kind of grouping because disjunction is a
> > requirement. It also makes nested optionals possible but we haven't
> > decided on those yet. The proposal isn't finished or fixed; at least
> > it can capture the test cases we will need.
> 
> I think it was already clear to me why we need grouping now (and I was
> not arguing/talking whether or not we need it) I simply wonder what
> would be the best syntactic choice from an average programmer/user
> point of view. And I feel it is good to have this syntax discussion now
> and avoid to postpone it - rather we start prototyping the future DAWG
> language...
> 
> > 
> > 2/ We may relax the WHERE/AND split, so expressions can appear where
> > it is most natural for them to appear in the query pattern  Something
> > has to be done as constraints apply to a graph pattern group, not the
> > whole query, when we have grouping.  It has been pointed out that
> > constraints and triples and no different aside from syntactic form. 
> > A WG decision which I await.
> 
> sure it is clear
> 
> > A form based on "( pattern ) AND constraints" would work if the WG
> > decides to keep them separate.
> 
> I would vote for this - which is also closer to current RDQL syntax -
> or just replace AND with a better WITH or CONSTRAINTS keyword, to avoid
> to confuse the users with the meaning of that "and"  (due a
> graph-pattern is a bunch of AND-ed triple-patterns)
> 
> E.g. " ( pattern ) WITH constraints"
> 
> > 
> > 3/ The usage of triples written in () is not found else where.  It is
> > yet another way to write graphs (with variables).  Writing out all
> > the triples can be a bit tedious and N3 (rather Turtle+vars) allows
> > ";" and "," to be more concise.  Makes no difference to query
> > execution if the syntactic sugar is just flattened into triple
> > patterns. 
> > 
> > This has the advantage that the query has at least a similar form to
> > one of the data representations.  (RDF/XML is not a natural option
> > for templating here as far as I can see because of the need to write
> > variables into the XML.)
> 
> clear - but I find this N3/Lisp like syntax a bit far from simpler
> original SquishQL/RDQLsyntax - which most users still like...
> 
> that's also why I always liked the simplicity of rdfdb query language
> 
> http://www.guha.com/rdfdb/query.html
> 
> (see also simple insert syntax)
> 
> > 
> > 4/ The WG has a duty to not make alignment with rules difficult for
> > no good reason.  Yet-another-pattern language is just a nuisance. 
> > Maybe we can get sufficiently close, at least in part of the query
> > language, to help application writer, maybe we can't.  That suggests
> > not using [] for optionals BTW.
> 
> humm rules...ok...I will not speak about this :) I would rather leave
> it for discussion to others DAWG-ers...
> 
> > 
> > 5/ "Simpler" is a value judgement - you aren't a lisp programmer are
> > you :-)?  The counter argument is that multiple use of the same
> > symbol is confusing.
> 
> yes your feeling is right - I never learned Lisp :o)
> 
> > 
> > Re: USING:  having USING at the end is at odds with RDF
> > serializations where namespace prefixes are declared first.   It also
> > requires a two-pass paring process (second pass somewhere to fix up
> > qnames into URIs). 
> 
> yes it makes sense - but I then do not understand why we need to make
> the syntax so much N3 like, using PREFIX and use :prefix notation
> instead of current RDQL USING prefix FOR <URI>
> 
> anyway, yet another syntax discussion :)
> 
> cheers
> 
> Alberto
Received on Tuesday, 31 August 2004 10:53:13 GMT

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