W3C home > Mailing lists > Public > public-rif-wg@w3.org > March 2008

Lists in Core?

From: Sandro Hawke <sandro@w3.org>
Date: Thu, 13 Mar 2008 18:20:15 -0400
To: Gary Hallmark <gary.hallmark@oracle.com>
Cc: Michael Kifer <kifer@cs.sunysb.edu>, RIF WG <public-rif-wg@w3.org>
Message-ID: <15541.1205446815@ubuhebe>


> Michael Kifer wrote:
> > I started adding the lists, but doubts crept into my head after today's
> > discussion. My assumption was that the reason for the lists was to
> > benefit the dialects that have no function symbols.
> > (As Hasan noted today, it makes little sense to add lists to dialects with
> > function symbols.)
> >
> > But where are those dialects that do not have function symbols?  I thought
> that PR dialects need that, but PR people today said they do not.  In any
> > case, it seems that there is no good reason to stuff BLD with lists, since
> > BLD has function symbols. If we decide to keep lists for the future
> > potential function-less dialects, then they can be added to FLD only (since
> > FLD is a toolbox from which dialects pick-and-choose).
> > However, I somehow doubt that there will be takers: with lists you can
> > simulate arbitrary function terms and you get the same undecidability
> > results for entailment.

Gary replies:
> The PR systems I'm familiar with provide List builtins (e.g. at Oracle 
> we use java.util.List).  Rule conditions use builtin predicates like 
> contains(list, const) and builtin functions like get(list, index).  Rule 
> actions use mutators like append(list, const), remove(index), as so on. 
> 
> PR cannot support the BLD list semantics.  If it could, then PR could 
> also support function symbols. 
> 
> It's probably a bad idea to use the BLD list syntax for PRD given the 
> semantic differences.  So I don't think it matters much to PRD what the 
> BLD list syntax turns out to be.

What about the xpath functions on lists?

   http://www.w3.org/TR/xpath-functions/#general-seq-funcs

Those functions can all be provided by PRD engines using internal data
structures and in BLD engines using pairs.  I don't see why they
shouldn't be in Core, actually.  The pair view of them would only be
available in dialects with logic functions, though.

Can't we do that?

    -- Sandro
Received on Thursday, 13 March 2008 22:22:01 GMT

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