"This book gives a practical approach to understanding implementations of non-strict functional languages using lazy graph reduction. The book is intended to be a source of practical lab work material, to help make functional-language implementations ‘come alive’, by helping the reader to develop, modify and experiment with some non-trivial compilers. The unusual aspect of the book is that it is meant to be executed as well as read. Rather than merely presenting an abstract description of each implementation technique, we present the code for a complete working prototype of each major method, and then work through a series of improvements to it. All of the code is available in machine-readable form."