using standard functions by URI

XQuery/XPath functions have URIs.
e.g
  http://www.w3.org/2005/04/xpath-functions/#max

Suppose I write...

PREFIX ex: <http://example/vocab#>
PREFIX xfo: <http://www.w3.org/2005/04/xpath-functions/#>

SELECT ?n
WHERE { ?who ex:name ?n
        FILTER xfo:matches(?n, "Dan") . 
      }


That's a core SPARQL query, right? It works just as well as...

PREFIX ex: <http://example/vocab#>

SELECT ?n
WHERE { ?who ex:name ?n
        FILTER regex(?n, "Dan") . 
      }


I don't see any text to that effect in
http://www.w3.org/2001/sw/DataAccess/rq23/#extensionFunctions
$Revision: 1.300 $ of $Date: 2005/04/14 11:43:04 $

I think it's worth testing too.


-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
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