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Re: ISSUE-12: xs:string VS plain literals: proposed resolution

From: Alex Hall <alexhall@revelytix.com>
Date: Fri, 6 May 2011 10:28:19 -0400
Message-ID: <BANLkTinVdA6-PXymbNsfsMkqzc_MWULB8g@mail.gmail.com>
To: Andy Seaborne <andy.seaborne@epimorphics.com>
Cc: "public-rdf-wg@w3.org" <public-rdf-wg@w3.org>
On Friday, May 6, 2011, Andy Seaborne <andy.seaborne@epimorphics.com> wrote:
>
>
> On 06/05/11 13:32, Alex Hall wrote:
>
> On Friday, May 6, 2011, Andy Seaborne<andy.seaborne@epimorphics.com>  wrote:
>
>
>
> On 04/05/11 20:13, Pat Hayes wrote:
>
> I am confused. There seems to now be a consensus view that plain,
> untyped literals are a Good Thing, to be preferred to clunky typed
> literals.  But the last time I encountered this whole issue of plain
> literals in RDF, there was a very strong consensus that plainness was
> a problem, and everything would be better if - in fact, for some,
> life would be possible only if - all literals had a type. Which is
> why the rdf:PlainLiteral type was invented, to be the type of these
> anomalous entities that had no type, in order that every literal
> would have a type.
>
> So, can anyone enlighten me? Are typed literals good or bad? Is
> plainness beautiful, or a dire problem? And are there any actual
> arguments either way, or is this all based on intuition and
> aesthetics?
>
> Pat
>
>
> I can take a partial explanation of this ... hopefully we can build a complete picture.  This is only my post hoc rationalisation.
>
> People writing data like to write "foo".  They don't really see the need to write "foo"^^xsd:string.  Just like writing 123 for "123"^^xsd:integer. This is the syntax and appearance side of the issue.  What is serialized by "foo"?
>
>
> If that's the only reason to have untyped literals then I'd prefer to
> see all literals as typed in the abstract syntax and "a" used as a
> shortcut for "a"^^xsd:string in the concrete syntax. It would simplify
> implementation logic (no longer have to check for no datatype as a
> special case) and align better with RIF and OWL. It does leave open
> the question of how to treat language tags.
>
> I hesitate to formally propose that, however, because it would mean
> reworking a lot of legacy code, and because making such a major change
> to the RDF Concepts the week SPARQL goes to last call could jeopardize
> their work.
>
> -Alex
>
>
> Alex,
>
> Does using rdf:PlainLiteral internally (i.e. convert on input and output only) achieve the simplification of the implementation logic?
>

rdf:PlainLiteral is a good alternative for interoperating with systems
that enforce typing of all literals, but it trades off one complexity
for another because you now have to crack open the lexical part and
split on '@' to get at the value. And it's still syntactically
distinct from the equivalent xsd:string term, so I don't think it gets
you much closer to the original goal of unifying "a" and
"a"^^xsd:string.

I hate to drop off this conversation now but I'm heading out of town
for a long weekend and will pick back up on Monday.

-Alex

>         Andy
>
Received on Friday, 6 May 2011 14:28:46 GMT

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