Unwrap or Throw - Make the Safe Choice Easier

[FranzBusch]

@Joe_Groff

With Never in the type system, and rethrows autoclosures, we could conceivably make it so that break , continue , and return were also expressions, and plumb them through autoclosures as if they were thrown errors so that they can branch out to the right places in the outer function. This would allow ?? to be used as shorthand for a lot of trivial one-line guard let s that unwrap an optional or immediately exit scope on nil.

This sounds amazing to be honest. Having a simply one liner for guard let x = .. else { return } would be so useful.