The review of SE-0039 "Modernizing Playground Literals" ran from Mar 7…9, 2016. The proposal has been accepted with modifications:

• The community and core team uniformly agree that this proposal increases uniformity in the swift language.
• We discussed how to rationalize naming and capitalization of identifiers in the “#” namespace and prefer to move to a model where it uses lower camel case.
• The argument label on imageLiteral should be “resourceName” to describe the role of the string and avoid needless words, following the naming guidelines from SE-0006.

As such, the preferred spelling of these literals are:

#colorLiteral(red: 0, green: 0, blue: 0, alpha: 0)
#imageLiteral(resourceName: “foo")
#fileLiteral(resourceName: “bar”)