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Re: Please add RDF term checking operators to sparql

From: Dan Connolly <connolly@w3.org>
Date: Tue, 25 Jan 2005 10:45:13 -0600
To: Dave Beckett <dave.beckett@bristol.ac.uk>
Cc: RDF Data Access Working Group <public-rdf-dawg@w3.org>
Message-Id: <1106671513.5075.135.camel@localhost>

On Tue, 2005-01-25 at 10:36 -0600, Dan Connolly wrote:
> On Tue, 2005-01-25 at 16:13 +0000, Dave Beckett wrote:
[...]
> > I'm asking for 'is float' functionality for the three types of RDF Term
> > that matter, literal, URI and blank node.
> 
> No, I don't think you are. I think you want a function
> that always returns false for isLiteral(<w3cstats#name>)
> even if <w3cstats#age> denotes the same thing that "W3C"
> denotes.

Another example, more directly analagous to isURI(): in
python, you can't write a function isVar() that can tell
the difference between isVar(v) and isVar(2.0) ala:

	v = 2.0
	if isVar(v): print "pass"
	if isVar(2.0): print "fail"

You can do it with something like C preprocessor macros
or lisp special forms; they work at the syntax level. But with
normal functions on objects in the domain of discourse, you
can't.


-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
D3C2 887B 0F92 6005 C541  0875 0F91 96DE 6E52 C29E
Received on Tuesday, 25 January 2005 16:45:15 GMT

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