static new ThreadLocal<Bool> applyNLLogicFacts_v4_verbose;

svoid applyNLLogicFacts_v4(S input, VF2<IfThen, NLLogicChecker_v2.Matching> onRuleFired) {
  applyNLLogicFacts_v4(input, onRuleFired, mL_facts());
}

svoid applyNLLogicFacts_v4(S input, VF2<IfThen, NLLogicChecker_v2.Matching> onRuleFired, LS facts) {
  applyNLLogicFacts_v4(input, onRuleFired, facts, ai_mL_parsedLogicExamples2());
}

svoid applyNLLogicFacts_v4(S input, VF2<IfThen, NLLogicChecker_v2.Matching> onRuleFired, LS facts, L<IfThen> rules) {
  new NLLogicChecker_v2 c;
  c.matcher = new NLStringMatcher_dollarVars;
  addAll(c.facts, facts);
  c.input = input;
  
  applyNLLogicFacts_v4(c, onRuleFired, rules);
}

svoid applyNLLogicFacts_v4(NLLogicChecker_v2 c, VF2<IfThen, NLLogicChecker_v2.Matching> onRuleFired, L<IfThen> rules) {
  c.rules = rules;
  for (IfThen rule : rules) pcall {
    new NLLogicChecker_v2.Matching m;
    m.verbose = isTrue(applyNLLogicFacts_v4_verbose!);
    if (m.verbose)
      print("Checking rule: " + rule);
    if (c.checkRule(rule, m)) {
      print("Matched " + quote(c.input) + " with rule " + quote(rule));
      printStruct(m.matches);
      callF(onRuleFired, rule, m);
    }
  }
}

Began life as a copy of #1017761