static Exp nlLogic_transformShallow(Exp e, F1<Exp> f) {
  if (e == null) null;
  if (e cast And)
    ret And(nlLogic_transformShallow(e.a, f), nlLogic_transformShallow(e.b, f));
  if (e cast ExpNot)
    ret ExpNot(nlLogic_transformShallow(e.a, f));
  ret callF(f, e);
}

static IfThen nlLogic_transformShallow(IfThen rule, F1<Exp> f) {
  if (rule == null) null;
  rule = (IfThen) shallowClone(rule);
  rule.in = nlLogic_transformShallow(rule.in, f);
  rule.out = nlLogic_transformShallow(rule.out, f);
  ret rule;
}