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Re: [TTL] Differences between SPARQL and Turtle.

From: Andy Seaborne <andy.seaborne@epimorphics.com>
Date: Mon, 02 May 2011 11:13:37 +0100
Message-ID: <4DBE83D1.6040205@epimorphics.com>
To: Ivan Herman <ivan@w3.org>
CC: public-rdf-wg@w3.org
Hi Ivan,

 >> # 4 RDF Collections as triple patterns
 >> No action.
 >> Not in Turtle, leave in SPARQL.
 >
 > Not that it is terribly important, but any reason why not allowing it
 > in Turtle, too? Or any major reason to leave it in SPARQL (apart from
 > backward compatibility...). I looks to me as being equally useless in
 > both languages...:-)

There is no technical reason why it can't be added .  Because you have 
to avoid

() .

which is no triples, it warps the grammar a bit.

There is no (major) reason to leave it in SPARQL that I know of.  I have 
only seen it in test cases (that I wrote :-)).  It is legal N3 (but so 
is "() . ")

>> # 8 Escape Processing Proposal: Adopt Turtle style / Change
>> SPARQL.
>>
>> \u escapes can only appear in strings and IRIs \u do not appear in
>> the grammar but are described separately as at present.
>>
>> This is a change to SPARQL but in an area rarely seen.
>
> Do you mean that adopt Turtle with that additional extension?

I was just proposing in strings and IRIs as per the current Turtle 
working draft.

> If my
> understanding is correct, that would make a:\u03B1 also valid and
> standing for a:α, right?

Not as I have proposed.  There has been some push back on that.

> I think that, for internationalization purposes, it is important that
> this should be valid in Turtle; one does not always have the
> possibility to type a:α in one's file...

That was my argument for making \u processing apply before parsing. 
Then it also applies to comments as well.

I don't agree with Richards comments here because if it's done before 
parsing, so newlines etc are still in the parser input whether they are 
written as newlines or as \u000A.  It's all unicode codepoint 10 to the 
parser.


I think we only have \u because it's needed for N-triples which is 
US-ASCII.  If it weren't for that, I don't see why we need \u-escapes at 
all.

Computers have other ways of inputting characters not on the keyboard 
like virtual keyboards or charmap programs.

The N-triples doc [*] does actually say that \u can only be used for 
certain characters (see table).  However, that's fairly impractical to 
enforce.

So removing \u-escapes would be an option except for backwards 
compatibility for N-triples.


[*] http://www.w3.org/TR/rdf-testcases/#ntrip_strings

> If all this is true, then let us go ahead with the proposal...
>
> Ivan

	Andy
Received on Monday, 2 May 2011 10:14:07 GMT

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