Tabling and Memoization about ergo HOT 1 CLOSED

I'm unclear on why SWI requires attributed variables for tabling. It probably has to do with constraint solvers.

For the time being, tabling has been implemented as follows:

1. Tabled predicates are marked by the :- table directive;
2. Tabled predicates are rewritten into several aux predicates plus a wrapper predicate that calls tabled/1 with the (unified) head of the aux predicates as argument;
3. tabled/1 implements SLDT resolution and overrides the regular SLD resolution for the affected predicates. It's working for the Fibonacci sequence, at least.

from ergo.