For example R developers usually document functions, data, etc using Roxygen in-line comments and they use vignettes for tutorials and the like. An additional advantage of R is that it checks that the documented function arguments line up with the code function arguments (at least by name -- it has no way to judge whether what the developer makes sense, of course).
I'm not saying that this is not useful, because I think it is, very, useful. It's just that this seem more like catching up than leading, at least in the broad strokes.
> it looks pretty much like what folks have been doing in other languages for a long time.
It looks pretty much like what folks have been doing in Swift for a very long time. DocC is just Apple’s own version of Jazzy / SwiftDoc / appledoc. There’s no catchup here, it’s just Apple making an “official” version of something that already exists.
Also: Xcode has been able to parse and display the Markdown documentation comments in Swift code for years. It's really nice! Doesn't mean DocC isn't worthwhile, but at least the PSOTU and Meet DocC presentation seemed to not only ignore outside prior art, but Xcode's existing capabilities too.
For example R developers usually document functions, data, etc using Roxygen in-line comments and they use vignettes for tutorials and the like. An additional advantage of R is that it checks that the documented function arguments line up with the code function arguments (at least by name -- it has no way to judge whether what the developer makes sense, of course).
I'm not saying that this is not useful, because I think it is, very, useful. It's just that this seem more like catching up than leading, at least in the broad strokes.