- From: Lee Feigenbaum <lee@thefigtrees.net>
- Date: Thu, 19 Mar 2009 10:07:57 -0400
- To: SPARQL Working Group <public-rdf-dawg@w3.org>
These two issues are similar: both share the idea that a new syntactical construct would allow scalar (i.e. non-aggregate) expressions to occur inline within triples. The first deals with putting expressions directly into triple patterns in the body of a query, and the second deals with putting expressions directly in the template part of a CONSTRUCT query. I have one main question and then some observations: 1) Are there existing implementations that do this in addition to Virtuoso (whether or not in a syntactically interoperable way)? Observations: As best I can see, [ScalarExpressionsInTriplePatterns] is purely surface syntax, and can always be replaced by a variable plus a filter on that variable. (Though there are some semantic differences between graph pattern matching and filter value matching, so the filter might need to use sameTerm rather than the '=' operator). Is this right? Also as best I can see, [ScalarExpressionsInConstruct] is not purely surface syntax on its own, but becomes surface syntax if the group chooses to pursue either Assignment or SubSelects+ProjectExpressions, both of which give SPARQL the capability to give names (variables) to values that don't explicitly occur in the query's RDF dataset graphs. Is this right? Other comments welcome! Remember: due to our time constraints, these discussions will in some cases end up substituting for the chance to discuss every proposed feature in teleconference, so get your comments / questions / advocacy in now, while you can! :) Lee
Received on Thursday, 19 March 2009 14:08:45 UTC