Re: N3 and Turtle Syntax Questions

Thanks Gregg.
You interpreted my earlier email better than I did - sorry!
Yes, I think it is only Production 8 that is the offender.
As an encouragement, I think it would then mean that there was more compatibility between N3 and turtle, which is the intention, of course.

Nice to see all this progressing to Recommendation - thanks to the team.
Hugh

On 10 Sep 2012, at 23:44, Gregg Kellogg <gregg@greggkellogg.net> wrote:

> \On Sep 10, 2012, at 9:59 AM, Hugh Glaser <hugh.glaser@seme4.com> wrote:
> 
>> Hi,
>> Sandro has asked on the SemWeb list if there are any comments on Turtle syntax.
>> I raised an issue (forwarded below) a few years ago, but it looks to me like the syntax is still the same.
>> 
>> I would like the syntax to allow comma and semicolon as a terminator (and thus also to be compatible with N3).
> 
> Production 7 does allow a statement to end with a semicolon:
> 
> [7]	predicateObjectList	::=	verb objectList (';' predicateObjectList?)*
> 
> However, production 8 does not allow this:
> 
> [8]	objectList	::=	object (',' object)*
> 
> It would be fairly easy, and would allow exactly the same form as 7, to just make it objectList ::= object (',' object?)*, or even objectList ::= object (',' objectList?)*. Either of these would create more recursive parser states and are certainly not optimal, but that's not really the standard for publishing normative grammars. I could go either way on making this change.
> 
> Gregg
> 
>> Hopefully the message is still sufficiently explanatory, but please ask if you need elaboration.
>> Best
>> Hugh
>> 
>> On 10 Jan 2008, at 02:25, Tim Berners-Lee <timbl@w3.org> wrote:
>> 
>>> Oh, I completely understand why -- that's indeed why N3 has it.
>>> (I have sed files for generating N3 -- very practical. Don't tell anyone.)
>>> Mind you, I have always been generating pred-object pairs,
>>> so I have used the ability to end in a semicolon, not a comma.
>>> 
>>> Tim
>>> 
>>> PS: IIRC  Pascal and Algol has the same problem. See e.g.http://www.lysator.liu.se/c/bwk-on-pascal.html "Pascal, in common with most other Algol-inspired languages, uses the semicolon as a statement separator rather than a terminator". Just because I shave it off doesn't mean it ain't grey ;-)  Ee bah gum, when I were a lad, were would be lucky to even *have* semicolons, ... ;-)
>>> 
>>> On 2008-01 -09, at 14:33, Hugh Glaser wrote:
>>> 
>>>> 
>>>> This was going to be a quick confirmation on N3 and turtle syntax for ';'
>>>> and ',', but seems to have got a bit complicated.
>>>> 
>>>> I want to write
>>>> 
>>>> @prefix owl:  <http://www.w3.org/2002/07/owl#> .
>>>> <http://southampton.rkbexplorer.com/id/person-00021>
>>>> owl:sameAs <http://citeseer.rkbexplorer.com/id/resource-CSP109020> ;
>>>> owl:sameAs 
>>>> <http://dblp.rkbexplorer.com/id/people-1726e6ee8fb20c8704f47285949b39b3-d101
>>>> 32da488b7179a8b1844f88470032> ;
>>>> .
>>>> 
>>>> Similarily:
>>>> @prefix owl:  <http://www.w3.org/2002/07/owl#> .
>>>> <http://southampton.rkbexplorer.com/id/person-00021> owl:sameAs
>>>> <http://citeseer.rkbexplorer.com/id/resource-CSP109020> ,
>>>> <http://dblp.rkbexplorer.com/id/people-1726e6ee8fb20c8704f47285949b39b3-d101
>>>> 32da488b7179a8b1844f88470032> ,
>>>> .
>>>> 
>>>> That is:
>>>> <#pat> <#age> 24;  <#eyecolor> "blue"; .
>>>> and
>>>> <#pat> <#child> [ <#age> 4 ], [ <#age> 3 ], .
>>>> 
>>>> Looking at the syntagmata in (1) and (2), my reading is that I can do this
>>>> for ';', although they have different structures:
>>>> N3 seems to do it by the possibility of () for propertylist.
>>>> Turtle seems to have an explicit optional ';' (in rule 7).
>>>> 
>>>> On the other hand, for ',':
>>>> N3 seems to do it by the possibility of () for objecttail.
>>>> However, I don't think I can do the same in turtle, as rule 8 in (2) lacks
>>>> the extra (',')?
>>>> 
>>>> (I would have downloaded the yacc grammar for N3 and tried it for real, but
>>>> the link on (3) to the yacc grammar gives 404, by the way.)
>>>> 
>>>> So the question is: have I got something wrong?
>>>> If not, then to use the second, ',', construct, I need to use N3, not
>>>> turtle.
>>>> So some questions are:
>>>> Is this what is intended, rather than an omission?
>>>> If so, why?
>>>> It seems a bit strange that such simple N3 is not compatible with turtle.
>>>> 
>>>> (1) http://www.w3.org/2000/10/swap/grammar/n3.n3
>>>> (2) http://www.dajobe.org/2004/01/turtle/#sec-tutorial
>>>> (3) http://www.w3.org/DesignIssues/Notation3.html
>>>> 
>>>> PS
>>>> And if you want to know why, it is because I want to generate a load of
>>>> sameAs triples. It is a common problem for program (and other) generators
>>>> not to want to know you are generating the last item in a list, and simply
>>>> treat the ';' or ',' as terminator, rather than separator. This can be
>>>> achieved by allowing null productions (as N3 above), or an explicit optional
>>>> (as turtle ';'), or by actually making it a terminator, although then you
>>>> tend to end up with ';;;' in the code.
>>>> And you can't put it at the front of each output either, otherwise you need
>>>> to treat the first item in the list specially.
>>>> (For the grey beards among us, this is why generating something like Algol68
>>>> was more of a pain than generating Pascal!)
>>>> 
>>>> Best
>>>> Hugh
>>>> -- 
>>>> Hugh Glaser,  Reader
>>>>             Dependable Systems & Software Engineering
>>>>             School of Electronics and Computer Science,
>>>>             University of Southampton,
>>>>             Southampton SO17 1BJ
>>>> Work: +44 (0)23 8059 3670, Fax: +44 (0)23 8059 3045
>>>> Mobile: +44 (0)78 9422 3822, Home: +44 (0)23 8061 5652
>>>> http://www.ecs.soton.ac.uk/~hg/
>>>> 
>>>> 
>>>> 
>>> 
>> 
>> --
>> Hugh Glaser
>> Chief Architect
>> Seme4 Limited
>> 18 Soho Square
>> LONDON
>> W1D 3QL
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>> 
>> hugh.glaser@seme4.com
>> www.seme4.com
>> 
>> Seme4 - the experts in semantic web and linked data applications
>> 
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> 

--
Hugh Glaser
Chief Architect
Seme4 Limited
18 Soho Square
LONDON
W1D 3QL
Mobile: +44 7595334155
Main: +44 2070601590

hugh.glaser@seme4.com
www.seme4.com

Seme4 - the experts in semantic web and linked data applications

Notice of Confidentiality. This e-mail message (including any attached
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Received on Tuesday, 11 September 2012 12:43:48 UTC