Hi,
This is a BIG feature request, but it is something that I use daily
via generators and I think we should bring it down into SPARQL itself
as it accounts for a very common usecase.
Of course I could try to write and push this into the next SPARQL
recommendation, but then it would eventually circle back to you guys
to see if you can implement it... So I guess the other way around
makes more sense ;)
The basic idea:
* There is a way to declare a global list of languages alongside a
query of arbitrary complexity
* These will be implicitly used to discern which literals to return
* The filtering is a bit more complex than a mere filter() as the list
imposes an "order of preference" amongst languages
So a sample query may look like this:
sparql
define lang "en-US,en,de,*"
select ?label where { ?something rdfs:label ?label }
Implicitly, the literals ( in this case ?label ) will be matched
against the languages defined in the pragma and the match with the
highest preference will be returned ( if any ).
This is analog to having an ordered set of UNION'ed clauses ( not easy
to accomplish as the order of evaluation is not deterministic ) or
several optionals with the following tests:
filter( langmatches( lang(?label), 'en-US' ) )
filter( langmatches( lang(?label), 'en' ) )
filter( langmatches( lang(?label), 'de' ) )
filter( langmatches( lang(?label), 'fr' ) )
filter( langmatches( lang(?label), null ) )
filter( 1=1 )
The latter ( 1=1 ) is the star (*) which matches "any" language. Even Zwagili ;)
The keyword "none" will match literals with no lang tag ( plain literals ).
Even for this trivial case we can see the advantage of using such
facility. Imagine what happens when there is more than one literal in
the query ( which is usually the case ).
What do you guys think?
Thanks!
A
--
Aldo Bucchi
skype:aldo.bucchi
http://www.univrz.com/
http://aldobucchi.com/
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