On Thu, 27 Mar 2003, Brian T Rice wrote:

> I guess I should mention that I'm extending Richard's goodie into a full
> relational algebra, which will allow composition, some lazy querying and
> (relational) iteration, and inversion.

Hmm...

Then I guess I should mention I've been working on the same thing for the
last few days ;).  You can find a snapshot of the Roe (Relational Object
Expression) library up at
http://beta4.com/squeak/aubergines/source/Roe.st.

I suspect we're approaching it rather differently, however. My main goal
has been to build an alternative way of interacting with relational
databases that's idiomatic to both Smalltalk (unlike SQL strings) and to
the data model (unlike O/R mapping).  It's an experiment, but I'm finding
it promising: the ability to compose and filter a bunch of relations and
then have a single SQL query generated as needed to produce the results
has some definite potential.

The same operations and lazy querying can also be performed with relations
that are purely in memory, but there's no optimization of the evaluation -
I'm using that more for testing purposes than for anything else.

Cheers,
Avi