Fri Apr 25 19:19:23 EDT 2008

better abstraction

1. the low level sequencer api:
     * make-breakpoint
     * with-breakpoints

2. high level lifting api: consists of adaptor functions constructed
   from state wrap/unwrap functions.

i'm REALLY close to figuring out the relation to monads, but can't
wrap my head around it yet. instead of applying the continuation in
'with-breakpoints', that operation should be abstracted.