svoid applyRule_random(S ruleID) {
  // process the rule
  Lisp rule = getLispTruth(ruleID);
  if (rule == null) { print("Rule not found: " + ruleID); ret; }
  //print("Applying rule " + ruleID);
  print_setPrefixForThread(ruleID + "> ");
  try {
    L<Lisp> conditions = dropLast(rule.args);
    Lisp out = last(rule.args);
    //for (Lisp cond : conditions) print("Condition: " + cond);
      
    new Map<S, Lisp> matches;
    int n = matchConditions_random(conditions, matches);
    if (n == -1) {
      print("Yo! " + struct(matches));
      out = lispReplaceVars(out, matches);
      if (lispTrue(out))
        print("Already had: " + out);
      else {
        print("Defining: " + lispToEnglish_prettier(out));
        emit(out, ruleID);
      }
    } else
      print("Only " + n + " of " + n(conditions, "condition") + " met");
  } finally {
    print_setPrefixForThread("");
  }
}