[swift-evolution] final + lazy + fileprivate modifiers

[Tino Heth]

Imho the only good "excuse" for "new private" are playgrounds.
They are often forgotten in discussions, but afaics, Swift aims to be a good language for teaching, so there is some impact on its design.

Of course, this is only speculation on motivation, as I wasn't involved in the decision to add any Playground-related features to Swift (or other features ;-)