tag foo[T] {
  arm(T);
}

fn altfoo[T](&foo[T] f) {
  auto hit = false;
  alt (f) {
    case (arm[T](?x)) {
      log "in arm";
      hit = true;
    }
  }
  assert (hit);
}

fn main() {
  altfoo[int](arm[int](10));
}