static SS nlLogic_expandMacros_funcShortNames = litmap(
  'o, 'output,
  'i, 'input);

// changes original rules
static void nlLogic_expandMacros(L<IfThen> rules) {
  for (IfThen rule : unnull(rules)) pcall {
    nlLogic_expandMacros(rule);
  }
}

static IfThen nlLogic_expandMacros(IfThen r) {
  if (r == null) ret r;
  int varCount = 0;

  S rendered;
  
  do {
    ping();
    rendered = str(r);
    nlLogic_visit(r, voidfunc(O o) {
      if (o cast Func) {
        S name = nlLogic_expandMacros_funcShortNames.get(o.name);
        if (name != null) o.name = name;
      }
    });
    
    Exp out = r.out;
    if (out cast Func) {
      S name = out.name;
      if (eq(name, 'sayIfTrue)) {
        r.out = Func('output, out.arg);
        r.in = And(r.in, Func('fact, out.arg));
      } else if (eq(name, 'inputToFact)) {
        r.out = Func('fact, out.arg);
        r.in = nlLogic_and(Func('input, restructure(out.arg)), r.in);
      } else if (eqOneOf(name, 'outputEval, 'evalOutput)) {
        S var = "$_" + ++varCount;
        r.out = Func('output, Sentence2(var));
        r.in = And(r.in, Eq(Sentence2(var), Func('eval, out.arg)));
        //print("Rewritten rule => " + sfu(r));
      } else if (eq(name, 'output)) {
        new Matches m;
        // in: output($x1, $x2 [...] and $x_n)
        do {
          L<S> tok = out.argText();
          if (!jmatch("*, * [...] * *", tok, m)) break;
          S x1 = m.get(0);
          if (!isDollarVar(x1) || !endsWith(x1, "1")) break with print("x1");
          S x = dropSuffix("1", x1);
          if (!eq(m.get(1), x + "2")) break with print("x2");
          //S lastSep = m.get(2);
          if (!eq(m.get(3), x + "_n")) break with print("x_n");
          // out: outputEval(joinWithComma_specialLast((LS) call(ai_context(), 'getList, "x"), " and "))
          out.name = 'outputEval;
          out.arg = Sentence2("joinWithComma_specialLast((LS) call(ai_context(), 'getList, " + quote(x) + "), "
            + quote(joinSubList(tok, l(tok)-5, l(tok)-2)) + ")");
        } while (false);
      }
    }
    
    // LHS only
    nlLogic_visit(r.in, voidfunc(O o) {
      // english a/an magic
      if (o cast Func)
        if (eqOneOf(o.name, 'input, 'fact)) {
          S s = ai_expandPatternForAAndAn(o.arg.text());
          if (s != null)
            o.arg = Sentence2(s);
        }
    });
  } while (neq(rendered, str(r)));
  
  ret r;
}