static <A> OKOrError<A> okOrError(IF0<A> f, bool printStackTrace default true) {
  try {
    ret OKOrError_ok(f!);
  } catch e {
    if (printStackTrace) printStackTrace(e);
    ret OKOrError_error(e);
  }
}

static <A> OKOrError<A> okOrError(Runnable r) {
  ret okOrError(runnableToIF0(r));
}