Companion code for the Purely Functional Data Structures book

The purpose of the book is to describe efficient approaches for functional algorithms

The book uses StandardML but I try to rewrite the described algorithms in idiomatic Clojure, you'll find:

• stack (LIFO)
• tree set (unbalanced binary tree)
• finite map (unbalanced binary tree)
• leftist heap (heap ordered binary tree with leftist property)