Higher-Order Perl

1st Edition

Transforming Programs with Programs

Authors: Mark Dominus
Paperback ISBN: 9781558607019
eBook ISBN: 9780080478340
Imprint: Morgan Kaufmann
Published Date: 14th March 2005
Page Count: 600
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49.99 + applicable tax
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Most Perl programmers were originally trained as C and Unix programmers, so the Perl programs that they write bear a strong resemblance to C programs. However, Perl incorporates many features that have their roots in other languages such as Lisp. These advanced features are not well understood and are rarely used by most Perl programmers, but they are very powerful. They can automate tasks in everyday programming that are difficult to solve in any other way. One of the most powerful of these techniques is writing functions that manufacture or modify other functions. For example, instead of writing ten similar functions, a programmer can write a general pattern or framework that can then create the functions as needed according to the pattern. For several years Mark Jason Dominus has worked to apply functional programming techniques to Perl. Now Mark brings these flexible programming methods that he has successfully taught in numerous tutorials and training sessions to a wider audience.

Key Features

  • Introduces powerful programming methods—new to most Perl programmers—that were previously the domain of computer scientists
    Gradually builds up confidence by describing techniques of progressive sophistication
    Shows how to improve everyday programs and includes numerous engaging code examples to illustrate the methods


Intermediate to advanced Perl programmers

Table of Contents

  • Preface
  • 1. Recursion and Callbacks
    • 1.1 Decimal to Binary Conversion
    • 1.2 Factorial
      • 1.2.1 Why Private Variables are Important
    • 1.3 The Tower of Hanoi
    • 1.4 Hierarchical Data
    • 1.5 Applications and Variations of Directory Walking
    • 1.6 Functional vs. Object-Oriented Programming
    • 1.7 HTML
      • 1.7.1 More Flexible Selection
    • 1.8 When Recursion Blows Up
      • 1.8.1 Fibonacci Numbers
      • 1.8.2 Partitioning
  • 2. Dispatch Tables
    • 2.1 Configuration File Handling
      • 2.1.1 Table-driven configuration
      • 2.1.2 Advantages of Dispatch Tables
      • 2.1.3 Dispatch Table Strategies
      • 2.1.4 Default Actions
    • 2.2 Calculator
      • 2.2.1 HTML Processing Revisited
  • 3. Caching and Memoization
    • 3.1 Caching Fixes Recursion
    • 3.2 Inline Caching
      • 3.2.1 Static Variables
    • 3.3 Good Ideas
    • 3.4 Memoization
    • 3.5 The Memoize Module
      • 3.5.1 Scope and Duration
        • Scope
        • Duration
      • 3.5.2 Lexical Closure
      • 3.5.3 Memoization Again
    • 3.6 Caveats
      • 3.6.1 Functions whose Return Values do not Depend on their Arguments
      • 3.6.2 Functions with Side Effects
      • 3.6.3 Functions that Return References
      • 3.6.4 A Memoized Clock?
      • 3.6.5 Very Fast Functions
    • 3.7 Key Generation
      • 3.7.1 More Applications of User-Supplied Key Generators
      • 3.7.2 Inlined Cache Manager with Argument Normalizer
      • 3.7.3 Functions with Reference Arguments
      • 3.7.4 Partioning
      • 3.7.5 Custom Key Generation for Impure Functions
    • 3.8 Caching in Object Methods
      • 3.8.1 Memoization of Object Methods
    • 3.9 Persistent Caches
    • 3.10 Alternatives to Memoization
    • 3.11 Evangel


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About the Author

Mark Dominus

Mark Jason Dominus has been programming in Perl professionally since 1992, when he was a UNIX sysadmin with the University of Pennsylvania Department of Computer and Information Sciences. Mark is an occasional contributor to the Perl Core, and is the author of the standard perlreftut man page as well as the Tie::File, Text::Template, and Memoize modules. From 1999-2001, Mark was the managing editor of the www.perl.com website. He was also a columnist for The Perl Journal for several years. All of his articles for TPJ have been reprinted in Computer Science and Perl Programming: Best of the Perl Journal, from O’Reilly and Associates. Mark’s other Perl-related articles have appeared in magazines such as Wiredand IEEE Software. Since 1998, Mark has been a professional Perl trainer. In addition to speaking at conferences such as YAPC, the O’Reilly Open Source Conferences, Usenix, and LISA, he has given training courses for large companies and organizations, including Morgan Stanley, IBM, Bristol-Myers Squibb, and the U.S. Air Force. Mark’s work on Rx, a Perl regular expression debugger, won the 2001 Larry Wall Award for Practical Utility.

Affiliations and Expertise

Plover Systems Co., Philadelphia, Pennsylvania, U.S.A.


“It's well written…everyone who claims to be an expert ought to read it…these techniques allow programmers to accomplish far more than they're used to."
—Gregory V. Wilson, Dr. Dobb's Journal, November 2005

"It is, quite simply, one of the best books on programming I have read for a long time."—Martin Schweitzer, Computing Reviews, Association for Computing Machinery, July 2005

"Mark Jason Dominus has hit his mark with Higher Order Perl. It is a very informative book that is a must read for Perl programmers who want to take their skills to the next level.”
—Mark Rutz, Linux Journal, November 2005

“Higher-Order Perl is one of the Perl books that should have a place on the bookshelf of every Perl programmer. It offers an in-depth understanding of important programming techniques and fundamental concepts. The chapter on parsing alone is worth the price of this book. I do not know a better text about parsing in Perl.”
—Reinhard Voglmaier, Unix Review, November 2005

“Higher-Order Perl is the most exciting, most clearly-written, most comprehensive, and most forward-looking programming book I've read in at least ten years. It's your map to the future of programming in any language."
—Sean M. Burke, Leading Programmer, Comprehensive Perl Archive Network (CPAN)

"There are lots of book that teach you new Perl modules or techniques. This book goes beyond that and teaches a new way to think about Perl programming.”
—Peter Norvig, Google Inc.

“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 eno