Functional Programming for the Object-Oriented Programmer

This book serves three overlapping audiences.
People who'd like to learn functional programming because they want to be ready if such languages become part of the mainstream. 
People who'll be working in an object-oriented language but want to use some functional programming idioms and tricks of the trade in their projects.
People with less specific goals, but who believe that learning languages that conceptualize problems and solutions in radically different ways will make them better programmers in general.
The book uses Clojure, a popular functional language that runs on the Java Virtual Machine. It contains many exercises and their solutions.