As a programmer, your bookshelf is probably overflowing with books that did nothing to change the way you program...or think about programming.

You're going to need a completely different shelf for this book.

While discussing caching techniques in Chapter 3, Mark Jason Dominus points out how a large enough increase in power can change the fundamental way you think about a technology. And that's precisely what this entire book does for Perl.

It raids the deepest vaults and highest towers of Computer Science, and transforms the many arcane treasures it finds---recursion, iterators, filters, memoization, partitioning, numerical methods, higher-order functions, currying, cutsorting, grammar-based parsing, lazy evaluation, and constraint programming---into powerful and practical tools for real-world programming tasks: file system interactions, HTML processing, database access, web spidering, typesetting, mail processing, home finance, text outlining, and diagram generation.

Along the way it also scatters smaller (but equally invaluable) gems, like the elegant explanation of the difference between 'scope' and 'duration' in Chapter 3, or the careful exploration of how best to return error flags in Chapter 4. It even has practical tips for Perl evangelists.

Dominus presents even the most complex ideas in simple, comprehensible ways, but never compromises on the precision and attention to detail for which he is so widely and justly admired.

His writing is--as always--lucid, eloquent, witty, and compelling.

Aptly named, this truly is a Perl book of a higher order, and essential reading for every serious Perl programmer.

When I picked up this book I thought, "You have to be kidding me." This book is very thin, and then a fair chunk of it is mathematics review for some of the formal arguments the book is going to be making later on. One wouldn't think there was much in this book.

One would be wrong. This book goes into rather impressive depth on some rather abstract concepts of computer science without dabbling for too long in the details. It does the best job I've ever seen of explaining the Turing machine and how it relates to computability and decidablity.

The exercises are both easy and insanely difficult - so you can basically chose your level and then go through the book, some of the problems are very hard, some are trivially easy, a great mix makes for great homework assignments.

The "Proof Idea:" sections before every proof give you the underlying concepts in plain english that are about to be stated formally so you have a clue what's happening when the formal definitions start flying. These are priceless and should be included in every other book that uses formal proof techniques.

The book reads fairly well on its own, or makes for a great class text book, which I used it for. As my professor said, "This is a good book because it doesn't have any extra words." but you don't seem to mind as you read it. Probably the best work on the science of computation in the world, certainly the best I've ever seen.