This book is a lesson to programming languages everywhere. The language definition is succinct, accurate, and to the point. Anyone who has attempted to penetrate such documents as the ANSI C or C++ standard is met with hundreds of pages of ambiguous, confusing language, about which formal reasoning is next to impossible. By contrast, this book describes the language syntax and semantics in a precise, mathematical style, making actual implementation of the language straightforward, as well as providing a usable definition for reasoning about the correctness of implementations. This is an example of how language definitions should be done.