snapshot of a little work I did on Saturday;  sieve3 is taking shape,  the main question is putting together a story that makes sense for I/O;  so far I've been coding with primitive triples but it could make sense to use Jena triples here;  it is a question of do I want to write a good output plugin for PrimitiveTriples or a good input plugin for Jena triples.  Jena might be more short term bother,  but long term it's the better choice