Add a new max_with_block predicate for more convenient usage

Based on Shawn's Prolog examples from the last Gerrit User Summit this
predicate should become a part of the standard library supplied by
Gerrit to rules.

For example, the typical default submit rule can be implemented as:

  submit_rule(submit(V, CR)) :-
    max_with_block(-2, 2, 'Code-Review', CR),
    max_with_block(-1, 1, 'Verified', V).

Change-Id: Id6d9d248e5b131f8625a912f62f30492b9ebf564
Signed-off-by: Sasa Zivkov <sasa.zivkov@sap.com>
1 file changed