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;
  Exp out = r.out;
  int varCount = 0;
  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));
    }
  }
  
  nlLogic_visit(r, voidfunc(O o) {
    if (o cast Func) {
      S name = nlLogic_expandMacros_funcShortNames.get(o.name);
      if (name != null) o.name = name;
    }
  });
  
  // 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);
      }
  });
  
  ret r;
}