The descriptive power and semantic elegance of modern functional languages make it possible to develop correct programs relatively quickly. Efficient implementations of functional languages, employing graph rewriting techniques, have only recently become available. This book illustrates the techniques of functional programming in Miranda and Clean, and focuses on the computational model of Graph Rewriting Systems for both sequential and parallel machines. Highlights of the book include a clear tutorial guide to functional programming in Miranda and Clean, in-depth coverage of implementation on both sequential and parallel machines, and unique focus on Graph Rewriting Systems as a computational model. The book will be equally valuable for students taking courses in functional programming, and for programmers or systems designers who are keen to explore state-of-the-art programming and implementation techniques. The Concurrent Clean System, which is available from the authors, offers the opportunity to write both sequential and parallel applications (including window-based systems) in a pure, lazy functional language.