Immutable Collections for Java

Library providing immutable/persistent collection classes for Java. While collections are immutable they provide methods for adding and removing values by creating new modified copies of themselves. Each copy shares as much as possible of its structure with other copies to minimize memory consumption.

The library includes a singly linked (cons/cddr style) list/stack, an integer trie based indexed list, a 2-3 tree based random access indexed list, a 2-3 tree based map, a hash trie based map, and hash and tree based sets, and sparse arrays. All collections provide immutable Cursor as well as standard Iterator classes for looping through all elements.

A utility class provides functional style algorithmic processing of Cursors including foldLeft, foldRight, collect, select, and reject.

The 2-3 tree and integer trie classes are optimized for performance and can be used alongside java.util Collections when immutability is needed for safe data sharing.