MillScript-Util is a richer alternative to Java's
Collections framework. This API provides several
features not found in the standard Collections
framework. It clearly distinguishes between
immutability, updateability, and extensibility. It
provides unified lists, sets, and maps. It allows
a developer to choose when to share or copy
backing data store. Finally, it introduces the
notion of a default action, which is to be taken
when a mapping is not present.
