Higher-Order Perl TRANSFORMING PROGRAMS WITH PROGRAMS

Most Perl programmers, including the inventor of Perl, were originally trained as C and UNIX programmers. So the Perl programs that they write bear a strong resemblance to C programs. But Perl incorporates many features that have their roots in non-C programming 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 any other way, and also serve as an introduction to the techniques of functional programming for those who have not have come across them in a computer science curriculum. Functional programming is important because it can make code more flexible and reusable. 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. So instead of the programmer writing the whole program, the computer does the work. The application of these techniques to Perl has been the work of Mark Jason Dominus for many years. A well-known Perl developer, Mark is the author of several standard Perl modules and was the managing editor of www.perl.com from 1999-2001. He was also a columnist for The Perl Journal for several years and is a frequent speaker and lecturer at numerous Perl conferences and meetings.

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.

1. Recursion and Callbacks; 2. Dispatch Tables; 3. Caching and Memoization; 4. Iterators; 5. From Recursion to Iterators; 6. Infinite Streams; 7. Higher-Order Functions and Currying; 8. Parsing; 9. Declarative Programming

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.