static Map<Pair<S>, Bool> ai_isRuleSuitableForFunction_cache = synchroHashMap();

static bool ai_isRuleSuitableForFunction(S rule, S f) {
  Pair<S> p = pair(rule, f);
  Bool b = ai_isRuleSuitableForFunction_cache.get(p);
  if (b != null) ret b;
  try {
    callAndMake(f, rule, null);
    ai_isRuleSuitableForFunction_cache.put(p, true);
    true;
  } catch e {
    if (shortClassNameIs(e, "UnsuitableRuleException")) {
      ai_isRuleSuitableForFunction_cache.put(p, false);
      false;
    } else {
      ai_isRuleSuitableForFunction_cache.put(p, false);
      printException(e);
      throw FunctionIsBroken(f);
    }
  }
}