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Re: DTB: Problem/Erratum for DTBin function string-join

From: Axel Polleres <axel.polleres@deri.org>
Date: Tue, 15 Sep 2009 17:14:58 +0100
Cc: "Public-Rif-Wg \(E-mail\)" <public-rif-wg@w3.org>
Message-Id: <BEC329A0-EB84-45C8-9598-0CD47BF9B77D@deri.org>
To: <kifer@cs.sunysb.edu>
Michael,

we discussed that in the phone conference...
and the general opinion was to keep with the
easy fix I proposed unless you object.
Do you?

Thanks,
Axel


On 17 Aug 2009, at 21:52, Michael Kifer wrote:

> i think using lists is a cleaner solution in general
>
> On Mon, 17 Aug 2009 21:28:27 +0100
> Axel Polleres <axel.polleres@deri.org> wrote:
>
> > Hi all,
> >
> > While working on the all-builtins use case, I realize a slight
> > error/problem in DTB now with the function:
> >
> > func:string-join(...)
> >
> > its xpath/xquery counterpart fn:string-join(...)
> >
> > takes two arguments:
> > - a sequence of strings
> > - a "separator" string
> >
> > now I realize - since this function was introduced when we didn't  
> heva
> > lists in RIF yet, that we seem to have expected a "flattened" list  
> as
> > input, i.e. we give the schemas
> >
> > ( ?arg1 ?arg2; func:string-join(?arg1 ?arg2 ) )
> >
> > ( ?arg1 ?arg2 ?arg3; func:string-join(?arg1 ?arg2 ?arg3 ) )
> >
> > ...
> >
> > ( ?arg1  ?arg2 ... ?argn; func:string-join(?arg1 ?arg2 ... ?argn ) )
> >
> >
> > Anyways, the semantics is defined in terms of fn:string-join, which
> > didn't work so far, but only works with a small fix, i.e.  
> interpreting
> > the first n-1 arguments as the sequence argument of the CPAth/Xquery
> > fn:string-join function. "Historically" this is IMO what we meant,  
> as
> > there was no lists.
> >
> > Thus, I see two options for fixing this:
> >
> > a) stick with the flattened version, interpreting the first n-1
> > arguments as the sequence argument of the CPAth/Xquery fn:string- 
> join
> > function and the last argument as the separator string.
> >
> > b) make the function with a fixed arity of 2,  the domain of the  
> first
> > argument being a list of strings and the second argument the  
> separator
> > string.
> >
> > I implemented option a) now, since it is the "least intrusive"  
> change to
> > the current doc, see
> >
> > http://www.w3.org/2005/rules/wiki/index.php?title=DTB&diff=10665&oldid=10495
> >
> > however, b) seems somehow the more natural way to proceed. The
> > disadvantage/worry I see with b) is that we might want to implement
> > "emulating" sequences by lists as input in other functions as  
> well...
> > Opinions?
> >
> > Axel
> >
> >
> >
>

-- 
Dr. Axel Polleres
Digital Enterprise Research Institute, National University of Ireland,  
Galway
email: axel.polleres@deri.org  url: http://www.polleres.net/
Received on Tuesday, 15 September 2009 16:15:40 GMT

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