[Versa] Versa issue: subgraph primitives?

[Uche Ogbuji]

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.


-- 
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