Xcode 7 beta 6 brings more changes to the standard libraryscape:

• The free function slaughter continues. The newest release guts the remainder of the free functions, moving nearly everything possible into a protocol extension. Left alone, abs() whistles pointedly, refusing to make eye contact with SignedNumberType or AbsoluteValuable. Its days are numbered.

• The Lazy* group of types and protocols have been updated significantly, with clearer naming and official protocols for LazySequenceType and LazyCollectionType.

• MutableSlice, MutableIndexable, and ReverseIndexType all join the family to support new mutable collection slicing capabilities. Welcome, everyone!

• Many methods that take closures, like map, filter, and contains, are now marked as rethrows, so they can accept throwing closures and pass on any thrown errors.