static S nlLogic_outputFromRuleWithParams(RuleWithParams r) {
  for (Exp e : nlLogic_unrollAnd(r.rule.out)) {
    e = c.apply(e, r.matches);
    if (e cast Func)
      if (eqOneOf(e.name, 'output, 'say))
        ret nlLogic_text(e.arg);
  }
  null;
}