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LET/assignment

From: Lee Feigenbaum <lee@thefigtrees.net>
Date: Mon, 28 Jun 2010 13:01:51 -0400
Message-ID: <4C28D57F.3010606@thefigtrees.net>
To: SPARQL Working Group <public-rdf-dawg@w3.org>
I'd like to start another -- hopefully final -- discussion on the topic 
of whether or not we want to include the assignment feature 
(http://www.w3.org/2009/sparql/wiki/Feature:Assignment) in SPARQL 1.1.

The brief history here, as best I can remember/reconstruct it, is:

1. Proposed as feature during WG's original requirements gathering phase

2. Received significant support but missed the cut for what we chose to 
work on (http://plugin.org.uk/misc/votes2.svg)

3. Raised on the -comments list by Holger Knublauch of TopQuadrant in 
late October and a few dys later again by Jeremy Carroll of TopQuadrant 
(http://lists.w3.org/Archives/Public/public-rdf-dawg-comments/2009Oct/0003.html 
followed by 
http://lists.w3.org/Archives/Public/public-rdf-dawg-comments/2009Nov/0000.html)

4. Assignment/LET was discussed, at least informally, at F2F2. Other 
keywords were suggested (e.g. BIND) as alternatives to LET. No consensus 
was reached on whether to include a dedicated syntax for assignment.

5. We discussed these comments internally in a thread starting near 
http://lists.w3.org/Archives/Public/public-rdf-dawg/2009OctDec/0392.html .

6. Andy provided some details on how the semantics of LET and SELECT 
expressions relate in late November: 
http://lists.w3.org/Archives/Public/public-rdf-dawg/2009OctDec/0540.html

7. We were asked about this feature by a TopQuadrant user (or employee, 
I actually don't remember which) at the SPARQL 1.1 panel at SemTech.

I believe in the intervening time, there are implementations other than 
Open Anzo (Glitter) and ARQ which include LET. Is this true?

I believe that Andy feels that this construct would be a syntactic 
addition that directly invokes the current draft's Extend operation: 
http://www.w3.org/2009/sparql/docs/query-1.1/rq25.xml#defn_extend

Based on this history, does anyone have feelings for or against 
including this work? I'd like to discuss over email and then probably in 
next week's teleconference. I'm hoping to resolve the issue (I've 
created ISSUE-57 to track this) relatively soon and move on.

thanks,
Lee
Received on Monday, 28 June 2010 17:02:32 GMT

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