125 of 128 people found the following review helpful
5.0 out of 5 stars
Aptly named, April 7 2005
By Damian Conway - Published on Amazon.com
This review is from: Higher-Order Perl: Transforming Programs with Programs (Paperback)
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.
53 of 55 people found the following review helpful
5.0 out of 5 stars
An instant classic, Mar 28 2005
By M. Friedman - Published on Amazon.com
This review is from: Higher-Order Perl: Transforming Programs with Programs (Paperback)
Many in the Perl community have been eagerly awaiting Higher Order Perl, and they will not be dissapointed. Not only is this a great Perl book, it's one of the best general computer science texts I've read in a long time. Dominus focuses on the functional, LISP-like aspects of Perl, breaking readers of the procedural habits they have developed writing Perl code. The book starts with a few simple examples of callbacks and closures, and quickly moves on to developing functions that dynamically manufacture and return other functions. These techniques are used to their fullest potential as Dominus shows us how to use dynamic iterators to eliminate recursion; an invaluable technique considering Perl's lack of tail call optimization. Further techniques include using iterators to transform other iterators (analagous to Perl's map function), currying, using linked lists to create "lazy" streams that produce their data upon request, and function memoization. Dominus also makes digressions into Perl internals, giving the reader a magnificent depth of understanding about how these techniques actually function under the hood.
16 of 16 people found the following review helpful
5.0 out of 5 stars
Lives up to the expectations, Aug 6 2006
By Eli Bendersky - Published on Amazon.com
This review is from: Higher-Order Perl: Transforming Programs with Programs (Paperback)
In "Higher Order Perl" (or HOP as it's affectionately called in the Perl community), the renown Perl wizard Mark Jason Dominus (MJD) shows how to take Perl coding to the next level by applying advanced programming techniques from the domain of functional programming.
The book covers recursion (including methods to convert recursive code to iterative code), iterators, streams, memoization, currying, parsing, constraint programming and higher order functions (functions that take functions as arguments and/or return other functions). It is packed with great, sophisticated code which is explained very well and is a model for correct programming. The author takes an approach similar to Peter Norvig's PAIP - advanced coding techniques are presented, and then non-trivial programs are written to demonstrate these concepts.
The comparison with Lisp here is unavoidable, and MJD talks about Lisp in his preface. He claims that Perl shares 6 of the "7 features unique to Lisp" quoted from Norvig's PAIP, and that this basically means that most of what can be written in Lisp can be written in Perl in roughly the same manner. But as he himself admits in a later interview, the 7th "missing feature" of Lisp, namely its uniform syntax, is what *really* differentiates Lisp from the rest. Lisp's syntax allows a very clean handling of higher-order functions, list-processing, and most importantly macros. The contrast between MJD's own code in HOP and Norvig's PAIP code is the best example for this fundamental difference. Be MJD's code as clean and nice as it is (for Perl, anyway), it is nowhere near the sheer aesthetic appeal of Norvig's Lisp.
Still, Lisp is Lisp and Perl is Perl, and each has its respectable place in the world of programming. HOP is a great book to read, and I warmly recommend it to any intermediate+ Perl programmer. For people who have never programmed in Lisp or have never learned functional programming techniques, this book is a must - it will literally take your code to a higher level. For diehard fans of Lisp, this book demonstrates how to employ most of your favorite techniques in the most practical language out there (though the Perlish syntactic sugar will at times make your teeth grind).