* Clause creation and destruction (`asserta/1`, `assertz/1`,
`retract/1`, `abolish/1`) with logical update semantics (_done_).
* Backtrackable and non-backtrackable global variables via `bb_get/2`
- `bb_put/2` (non-backtrackable) and `b_bb_put/2`
+ `bb_put/2` (non-backtrackable) and `bb_b_put/2`
(backtrackable). (_done_).
* Streams and predicates for stream control (_in progress_).
* An incremental compacting garbage collector satisfying the five
* `atom/1`
* `atomic/1`
* `bagof/3`
+* `bb_b_put/2`
* `bb_get/2`
* `bb_put/2`
* `between/3`