[Someone]

Agreed. Also, it does look different aka innovative to me:

    func loadData() throws { }

    func test() {
      do {
        try loadData()
      } catch {
        print(error)
      }
    }

I guess that you have to prefix any statement that might throw with 'try', and cannot prefix other statements with it.

If so, their motto really seems to be 'explicit over implicit'. I'm not sure that is an improvement, but I'm not sure that it is bad, either, provided that the refactoring tools work fine (for example when one removes that "throws" from the definition of loadData)

[72deluxe]

Doesn't that mean typing try a million times instead of putting potentially throwable calls inside one try block and a bunch of different catch handlers?

I wonder why they insist on that. Perhaps it is easier to parse?

[lobster_johnson]

I suspect it's useful to visually signal that the call can fail, and make it obvious what's happening; after all, the "throws" annotation is at the target site, not on the caller end.

You need to prefix anything that throws with a "try":

    func mightThrow() throws {
      try mightAlsoThrow();
    }

Other than that, it looks exactly like C++ exceptions: Propagation happens along the chain of functions marked as "throws", until a "catch" handler intercepts it.

"try" is an expression, by the way, so you can do things like:

    let line = try file.readline()

There's also a "try!" statement that throws a runtime exception if the inner statement throws.