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Re: ISSUE-92: n-ary builtins

From: Axel Polleres <axel.polleres@deri.org>
Date: Fri, 27 Feb 2009 22:15:34 +0000
Message-ID: <49A86606.6080605@deri.org>
To: Chris Welty <cawelty@gmail.com>
CC: "Public-Rif-Wg (E-mail)" <public-rif-wg@w3.org>
slight problem for 3 if feasible (BLD editors need to agree, but 
Michael's mail seems to indicate green light?)

Chris Welty wrote:
> The basic issue is that BLD (and core) require all predicates and 
> functions to have a fixed arity, but in DTB we reuse many xpath/xquery 
> functions and predicates, and there are several that do not have a fixed 
> arity (e.g. concat).      In DTB, the treatment of these operators is 
> unclear:
> "numbering the different versions of the respective built-ins and 
> treating the unnumbered version as syntactic sugar, i.e. for instance 
> instead of External( func:concat2( str1, str2) ) and External( 
> func:concat3( str1 str2 str3 ) ) we allow the equivalent forms External( 
> func:concat( str1, str2) ) and External( func:concat( str1 str2 str3 ) )."
> Does this mean that BLD should allow rulesets to use concat with any 
> arity, or does it mean that for the purposes of DTB we write concat as a 
> shortcut for whichever (concat2, concat3, etc) is appropriate?
> Possible solutions:
> 1) Make it clear this is only for the purposes of writing DTB, and that 
> all rulesets must use a fixed arity function/predicate
> 2) Allow for some preprocessing step in RIF implementations where 
> functions like concat are replaced with their fixed-arity equivalents
> 3) Change BLD to allow for arbitrary arity functions and predicates. I 
> can find no formal resolution to make preds/funs fixed arity, however it 
> would be a major change to a LC document (BLD).  At the last telecon, no 
> one was opposed to this change on technical grounds, only because of the 
> LC status.
> </chair>
> I prefer option 1.
> <chair>

Dr. Axel Polleres
Digital Enterprise Research Institute, National University of Ireland, 
email: axel.polleres@deri.org  url: http://www.polleres.net/
Received on Friday, 27 February 2009 22:16:29 UTC

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