- From: Steve Harris <steve.harris@garlik.com>
- Date: Tue, 1 Sep 2009 10:11:11 +0100
- To: "Seaborne, Andy" <andy.seaborne@hp.com>
- Cc: "public-rdf-dawg@w3.org Group" <public-rdf-dawg@w3.org>
On 31 Aug 2009, at 23:24, Seaborne, Andy wrote: >> -----Original Message----- >> From: public-rdf-dawg-request@w3.org [mailto:public-rdf-dawg-request@w3.org >> ] >> On Behalf Of Steve Harris >> Sent: 31 August 2009 22:44 >> To: public-rdf-dawg@w3.org Group >> Subject: Re: First attempt at a grammar for SPARQL/query 1.1 >> >> On 28 Aug 2009, at 18:22, Seaborne, Andy wrote: >>> >>> In the design pages we have some different proposals for the syntax >>> of select expressions: without mandating comma (which would break >>> backward compatibility), one case to remember is ?x-?y: Is that (? >>> x-? >>> y) or "?x" followed by "-?y"? This is why expressions get bracketed >>> a lot in SPARQL. >> >> Mandating comma when AS is used wouldn't break back compatibility, as >> AS was not legal in SPARQL. > > Steve, > > The three cases I found with syntax rules didn’t mandate commas (or > mention them). I couldn't see what is proposed under SurfaceSyntax > exactly but I didn’t see a proposal for mandatory commas in the > SELECT clause (meaning SELECT always has commas regardless of any AS > or expressions - that breaks compatibility). > > The proposal at Feature:SurfaceSyntax#Commas_in_expression_lists > does not state mandatory or optional commas. If the rationale is > familiarity, optional commas would be sufficient won't it? As > optional, adding ","? between the terms of the SELECT elements works > in the grammar doesn't it? > > For Feature:SurfaceSyntax#Commas_in_expression_lists > Would I now be right in guessing that there would be two syntaxes > proposed: > > SELECT ?x ?y ?z > > SELECT ?x, ?y, (?z+1 AS ?A) > Or alternatively > SELECT ?x, ?y, (?z+1) AS ?A I was imagining SELECT ?x ?y ?z or SELECT ?x, ?y, ?z+1 AS ?A Parenthesis are not required if we have commas. > (aside: which I don't consider to be mandating commas - there's a > non-comma form) > > It does state that these two are equivalent: "SELECT ?a, ?b, ?c" and > "SELECT ?a ?b ?c" > which I read as meaning that "SELECT ?a ?b ?c" (no commas) is still > legal. > > What about "SELECT ?x ?y , ?z"? I would prefer that to not be legal myself, but no strong preference. > What happens if ?z or (?x+?y) is added to the SELECT with a comma? > Does the earlier part now need to have commas added? That question seems to be about programatic construction. > (I found the statement "and it also makes the syntax of AS easier to > read," too black&white. I don’t find it easier to read but that is > considering only one AS design.) I guess it's a matter of opinion, but I find both parenthetical forms difficult to read - though one is worse than the other. I was never a fan of s-expressions either! - Steve -- Steve Harris Garlik Limited, 2 Sheen Road, Richmond, TW9 1AE, UK +44(0)20 8973 2465 http://www.garlik.com/ Registered in England and Wales 535 7233 VAT # 849 0517 11 Registered office: Thames House, Portsmouth Road, Esher, Surrey, KT10 9AD
Received on Tuesday, 1 September 2009 09:11:47 UTC