Comment by zZorgz

As others mentioned, it looks equivalent to using the try! macro (which I'm not sure this is supposed to replace?)

Another sane alternative here is using and_then, map, etc.

Writing from memory too:

  fn h() -> Result<(A, B), E> {
    f().and_then(|x| g().map(|y| (x, y)))
  }

..which seems to be a different style of control flow to choose from. On one hand, I suppose one may avoid using and_then with code dealing with side effects. On another hand, ? seems restricted to being used inside functions that have to return a a single type (like Result) they operate on.