A slice of Pizza:
A quick introduction to Pizza, a dialect of Java

Martin Odersky
University of Southern Australia - Philip Wadler
Lucent Technologies

10 October 1997

Abstract:

Pizza is a superset of Java that incorporates four additional features.

• Parametric polymorphism : the ability to parameterize classes over types, similar to (but safer than) templates in C++.
• Higher-order functions : the ability to treat functions as values, similar to inner classes in Java 1.1, but more convenient and more efficient.
• Algebraic data types : a convenient way of representing trees with support for pattern matching, providing advantages similar to the well-known `Composition' and `Visitor' design patterns.
• Tail calls : don't grow the stack when the last operation in one methods is to call another method; this enables one to replace iteration by recursion, and makes it easy to simulate finite-state machines.

Pizza contains Java as a subset, interworks smoothly with Java, and compiles into the Java Virtual Machine (JVM): so it runs wherever Java runs, including web browsers. Pizza is freely available from the Pizza website.

http://www.cs.bell-labs.com/~wadler/pizza

The Pizza compiler can be used to translate Pizza into Java or to generate JVM code directly; it runs faster than Sun's own javac compiler.