Is there any documentation of the string handling functionality of Kotlin? In particular, I am interested in syntactical support for slicing and regex matching and parsing.
Also, is there an equivalent of the slashy strings?
For string we have almost everything that Java does, plus some extra utility functions, see extension functions for String. For regex matching, use Java API.
There is no equivalent for slashy things, and it hardly will appear, because regular expressions are not used often enough to have special syntax in Kotlin.
How did you find that doc page? When I click on "All Classes" in the KotlinDoc, it does not show me anything in the jet.* packages?
Are there any extension functions/properties for Pattern and Matcher?
Kotlin API home → Packages / kotlin → Extensions / jet.String
Unfortunately, there are no extra regexp API yet.