Util's own stripped-down and modernized example of how to make a module.

CoolMod.pm

package CoolMod;
# Util's own stripped-down and modernized example of how to make a module.
# File must be named CoolMod.pm
# Usage: `use CoolMod qw( foo bar );`
use strict;
use warnings;
use base qw(Exporter);
our $VERSION   = 1.00;
our @EXPORT_OK = qw( &foo &bar );

sub foo {
    print "foo got @_\n";
}

sub bar {
    print "bar got @_\n";
}

1; # Mandatory!

test_cool.pl

#!/usr/bin/perl
use strict;
use warnings;
use CoolMod qw( foo bar );

foo( 'Hello', 99 );
bar( 'Hi', 'Max' );