static Map<S, Lisp> matchCondition_first(Lisp condition, Map<S, Lisp> m) {
  L<Lisp> facts = lispTruth();
  
  O evaluator = getLispEvaluator(condition.head);
  if (evaluator != null)
    ret isTrue(callF(evaluator, lispReplaceVars(condition, m))) ? m : null;

  L<Map<S, Lisp>> candidates = new L;
  for (Lisp fact : facts) {
    Map<S, Lisp> m2 = cloneMap(m);
    if (lispMatchIC_xyzVars_sub(condition, fact, m2))
      ret m2;
  }
  null;
}