W3C home > Mailing lists > Public > public-rdf-wg@w3.org > May 2013

PrEfIx and BaSe should be removed from Turtle

From: Gavin Carothers <gavin@carothers.name>
Date: Wed, 15 May 2013 19:48:58 -0700
Message-ID: <CAPqY83yAWTKKKFpLPBa49KHg_nehBAP7VMBTbpuDDKwW6YxYqw@mail.gmail.com>
To: RDF-WG WG <public-rdf-wg@w3.org>, "public-rdf-comments@w3.org" <public-rdf-comments@w3.org>
Cc: David Booth <david@dbooth.org>, David Robillard <d@drobilla.net>, Peter Ansell <ansell.peter@gmail.com>, Gregory Williams <greg@evilfunhouse.com>
 <https://gist.github.com/gcarothers/5589022#prefix-and-base-should-be-removed-from-turtle>PrEfIx
and BaSe should be removed from Turtle

PREFIX and BASE were added as features at risk to Turtle before CR.
Designed to make it easier to copy and paste between Turtle and SPARQL they
have proven controversial. As they are a controversial addition to a
settled language they should be removed.
 <https://gist.github.com/gcarothers/5589022#rationale>Rationale

The FPWD for the Turtle document published by this working group included
the following:

Turtle is already a reasonably settled serialization of RDF. Many
implementations of Turtle already exist, we are hoping for feedback from
those existing implementers and other people deciding that now would be a
good time to support Turtle. There are still a few rough edges that need
polishing, and better alignment with the SPARQL triple patterns. The
working group does not expect to make any large changes to the existing
syntax.

The laudable goal of reducing copy and paste errors in both Turtle and
SPARQL is not strong enough to change a settled serialization.

None of the arguments in support of the feature deal with what
serialization should be preferred. Introducing the feature also creates
issues with the existing @prefix and @base syntax and if they should or
should not require a trailing period. Again, there is no clear guidance for
serializers. This feature also introduces the first case insensitive
keyword in Turtle all other Turtle keywords are case sensitive.

Lastly, the goal of full copy and paste between SPARQL and Turtle will not
be achieved only by adding this feature. A range of other issues exist
preventing this.
 <https://gist.github.com/gcarothers/5589022#actions>Actions

   - Remove "Feature at Risk" box
   - Remove grammar rules 5s, 6s
   - Update grammar rule 3 to read prefixID | base
   - Change grammar note 1 to "All keywords are case sensitive"

The grammar at that point requires no magical understanding of case rules
as all rules express the case of their keywords.

<https://gist.github.com/gcarothers/5589022#ways-forward-for-those-that-like-copying-and-pasting-prefixbase>Ways
forward for those that like copying and pasting PREFIX/BASE

I'd direct your attention to the conformance section of the Turtle
document. http://www.w3.org/TR/turtle/#conformance "This specification does
not define how Turtle parsers handle non-conforming input documents." That
note is not there by mistake.

<https://gist.github.com/gcarothers/5589022#selected-messages-and-threads-from-outside-of-wg>Selected
Messages and Threads (From outside of WG)

Yes, I read all the threads again, just a few are included here.
 <https://gist.github.com/gcarothers/5589022#supporting>Supporting

David Booth david@dbooth.org http://www.w3.org/mid/516EAFDF.50708@dbooth.org

Copy and paste between Turtle and SPARQL is *very* common, particularly in
debugging. Having to change the prefix syntax back and forth is a
significant and pointless waste of time. Please find a path to a single
compatible syntax.
 <https://gist.github.com/gcarothers/5589022#in-opposition>In opposition

Gregory Williams greg@evilfunhouse.com 2013-03-01:
http://www.w3.org/mid/C52BE515-076D-4D10-82D0-27FD757F2F48@EVILFUNHOUSE.COM

I'd like to take this opportunity to provide feedback on the inclusion of
SPARQL BASE and PREFIX syntax in the new Turtle grammar. I think this is a
mistake, adding complexity for both users and implementors. I'm sympathetic
to the desire to align syntax for triples between Turtle and SPARQL, but
don't believe the alignment is necessary or recommended for the top-level
language syntax (as the need for backwards compatibility with pre-REC
Turtle means that alignment requires two different syntaxes for the same
declarations).

David Robillard d@drobilla.net 2012-10-08:
http://lists.w3.org/Archives/Public/public-rdf-comments/2012Aug/0028.html

For what it's worth, as a Turtle implementer I am opposed to this change.
It is ugly and inconsistent with the language, clearly an import that does
not belong.

While it is unfortunate that SPARQL did not use the @directive convention
from N3, Turtle does not contain SELECT and such either. While triple
copying and pasting between the languages is desirable (even if it has
polluted Turtle with path grammar and horrific escaping rules), the
directives between the two languages are not compatible.

I do not consider messing up the Turtle specification in this way
appropriate. If implementations want to support this as an extension, they
may. I won't.

Peter Ansell ansell.peter@gmail.com 2013-04-28
http://www.w3.org/mid/CAGYFOCQKfygwogHQj_b7=nW1CrxM4aq5XUdgJg4nx4uaUSKZFw@mail.gmail.com

I am sorry, but I completely disagree that changing a fundamental part of
an established syntax as part of its long-delayed "standardisation" process
can be rationalised by saying that hypothetical future users will
appreciate it and it doesn't matter what a community of current users think.
Received on Thursday, 16 May 2013 02:49:32 UTC

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