(documented in "Tabling as a Library with Delimited Control").
- [x] A _redone_ representation of strings as difference lists of
characters, using a packed internal representation.
-- [ ] clp(B) and clp(ℤ) as builtin libraries (_in progress_).
+- [x] clp(B) and clp(ℤ) as builtin libraries.
- [ ] Streams and predicates for stream control (_in progress_).
- [ ] A compacting garbage collector satisfying the five
properties of "Precise Garbage Collection in Prolog."