[Versa] Versa issue: subgraph primitives?

[Michael Olson]

On Aug 13, 2005, at 7:40 AM, Uche Ogbuji wrote:

> For a long time I (and apparently others) have felt that we really
> should have statements as first class objects.  I'm a bit less sure,  
> but
> think we should consider having subgraphs as first-class objects.
>
> Chime, responding to Kyle, offers some useful discussion along these
> lines:
>
> http://lists.fourthought.com/pipermail/4suite/2004-October/012919.html
>
> IMO, if we accept subgraphs as first-class objects, then we should dump
> statements as separate first-class objects.  A statement is, of course,
> just a special case of a subgraph.
>
> Traversal expressions would return a subgraph rather than a list of
> statements (or scalars right now).  As chime says, this would allow for
> very elegant composition, e.g. in chaining Versa queries.
>

Which ever route we choose to call it isn't list(statement) = sub  
graph?  Since lists are first class objects....

I guess, since in Versa just about everything is a list, then we really  
do have sub graphs as first class objects.  I still think we need to  
define what

item({sub-graph expression},0)

returns though.  I don't think it can be another sub-graph of length 1.

Mike


>
> --  
> Uche Ogbuji                               Fourthought, Inc.
> http://uche.ogbuji.net                    http://fourthought.com
> http://copia.ogbuji.net                   http://4Suite.org
> Use CSS to display XML, part 2 -  
> http://www-128.ibm.com/developerworks/edu/x-dw-x-xmlcss2-i.html
> XML Output with 4Suite & Amara -  
> http://www.xml.com/pub/a/2005/04/20/py-xml.html
> Use XSLT to prepare XML for import into OpenOffice Calc -  
> http://www.ibm.com/developerworks/xml/library/x-oocalc/
> Schema standardization for top-down semantic transparency -  
> http://www-128.ibm.com/developerworks/xml/library/x-think31.html
>
> _______________________________________________
> Versa mailing list
> Versa at lists.fourthought.com
> http://lists.fourthought.com/mailman/listinfo/versa
>
------------------------------------------------------------------------ 
-----------------
Mike Olson                                                Principal  
Consultant
mike.olson at fourthought.com                +1 720 253 4662
Fourthought, Inc.                                       
http://Fourthought.com
PO Box 270590,                                       http://4Suite.org
Louisville, CO 80027-5009, USA
XML strategy, XML tools, knowledge management