Agenda

• Introduction to Perl
• Perl History
• Perl Philosophy

Introduction

• A scripting language
• Operating systems can do many things
• copy, move, create, delete, compare files
• execute programs, including compilers
• schedule activities, monitor processes, etc.
• A command-line interface gives you access to these functions, but only one at a time
• A scripting language is a “wrapper” language that integrates OS functions

Some Scripting Languages

• UNIX has sh, bash, ksh, csh, perl
• Macintosh has AppleScript, Frontier
• Windows does not have any scripting languages – probably due to weaknesses of DOS
• Generic scripting languages include:
• Perl (most popular)
• Python (Java-like, best for large programs)

Perl

• “Practical Extraction and Reporting Language”
• Written by Larry Wall and first released in 1987
• Perl has become a very large system of modules
• Name came first, then the acronym
• “Perl is a language for easily manipulating text, files and processes“
• -Originally aimed at systems administrators and developers

What is Perl?

• Perl is a High-level Scripting language
• Faster than sh or csh, slower than C
• No need for sed, awk, head, wc, tr, …
• Compiles at run-time
• Available for Unix, PC, Mac
• Best Regular Expressions on Earth

Perl History

• 1986-87 – Perl was invented by Larry Wall at NASA’s Jet Propulsion Labs
• 1987-Dec Perl 1 introduced Perl to the world.
• 1988-Jun Perl 2 introduced Henry Spencer’s regular expression package.
• 1989-Oct Perl 3 introduced the ability to handle binary data.
• 1991-Mar Perl 4 introduced the first Camel book.
• 1994-Oct Perl 5 introduced everything else, (OOP, threads…)
• 2014-05-27 Perl 5.20 has been released by Ricardo Signes.
• Latest Version is 5.24

Perl Philosophy

• TIMTOWTDI
• TIMTOWTDI is pronounced “Tim Toady” and is:
• There is more than one way to do it
• Perl aims to be aggressively non-prescriptivist.
• Prescriptivism is the attitude or belief that one variety of a language is superior to others and should be promoted as such.
• Every problem should have multiple solutions.

Making easy things easy & hard things possible

• This quote comes from the front of Learning Perl, also known as the Llama.
• It goes hand-in-hand with TIMTOWTDI.
• Every problem has multiple solutions implies every problem has at least one solution 🙂

linguistics background

• Perl’s creator Larry Wall has a linguistics background, and took some of that with him when he designed Perl.
• Keywords such as “for”, “my”, “defined”, “say”, “do”, “while”, “if”, “unless”, and “use” all read quite nicely to English eyes as well as to programmer eyes.

Low Ambiguity

• In many languages this is acceptable:

puts 4 + 2                             # 6
puts “ram" + “n"               # “ramn"
puts “6" + 2                         # `+': can't convert num into String
In Perl we use different operators:
say 1 + 2;                              # 3
say “R" . “N";                      # “RN"
say "2" + 1;                          # 3
say "2" . 1;                           # 21

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