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Your Impression towards Perl?

  • Perl vs PHP

  • Perl vs Python

  • Perl vs Bash Shell script

Today's Flow

  • History
  • Perl Modules (CPAN Modules)
  • Perl Syntax
  • Live Coding

"Easy things should be easy, and hard things should be possible."

History

1987 - Perl 1995 - CPAN 1994 - Perl 5 2000-2019 - Perl 6 (change name to Raku) 2023 - Perl 5.38

cpan - The Comprehensive Perl Archive Network

https://www.metacpan.org

Install perl modules

  • cpan

  • cpanm Dist::Module

  • manually install through make and make install

Location of installed modules

~/perl5/lib/perl5

perldoc -l Dist::Module

Uninstall modules OR Reinstall

cpanm --uninstall Dist::Module cpan > force install Dist::Module

metacpan.org

  • check availability of perl modules

  • read manual

Tips: XS module(s)

use Math::Vector::Real; # Math::Vector::Real::XS

Example: cosine_similarity.pl

running Perl

one-liner

perl -E 'say "hello"' perl -e 'print $$'

https://learnbyexample.github.io/learn_perl_oneliners/

chmod +x perlscript.pl

perl perlscript.pl

Sigils - Scalar, Array, Hash, Subroutine

  • $scalar

  • @array

  • %hash

  • perldoc perlcheat

different ways of express False

  • 0
  • ''
  • undef
while (@ARGV) {
    say shift @ARGV;
}

different ways of applying delimiters

$ cat paths.txt

leaning toothpick syndrome

$ perl -ne 'print if //home/ram//' paths.txt

using a different delimiter makes it more readable here

$ perl -ne 'print if m{/home/ram/}' paths.txt

$ perl -ne 'print if !m#/home/ram/#' paths.txt

taken from https://learnbyexample.github.io/learn_perl_oneliners/line-processing.html

two ways of commenting

  • hash sign #

=pod 
This is a comment.
=cut

"Context"

my @arr = (1, 3, 2);
my $scalar = @arr;
my @n_arr = @arr;
say $scalar;
say join ",", @n_arr;

syntactic sugar

Definition: An alternative way of writing something more easily; a shortcut.

Perl's favorite default variable $_

_Regular Expression

Larry Wall

(1954 - )

  • Father of Perl

  • Studied Linguistics

"Wall was trained as a linguist, and the design of Perl is very much informed by linguistic principles. Examples include Huffman coding (common constructions should be short), good end-weighting (the important information should come first), and a large collection of language primitives. Perl favors language constructs that are concise and natural for humans to write, even where they complicate the Perl interpreter." - wikipedia

"Speakers of a natural language are allowed to have differing skill levels, to speak different subsets of the language, to learn as they go, and, generally, to put the language to good use before they know the whole language. You don’t know all of Perl yet, just as you don’t know all of English. But that’s Officially Okay in Perl culture. You can work with Perl usefully, even though we haven’t even told you how to write your own subroutines yet." - Programming Perl

3 Virtues of Perl Programmers

  • Laziness!!!

  • Impatience

  • Hubris

Websites Recommended

https://perldoc.perl.org/

https://metacpan.org/

https://learnbyexample.github.io/learn_perl_oneliners/

https://www.perlmonks.org

Read also:

https://raku-advent.blog/2022/12/20/sigils/

Live Coding

END

"The problem with being consistent is that there are lots of ways to be consistent, and they're all inconsistent with each other." -- Larry Wall

Thank you!!!