Perl isn't like bash, ksh, tcsh, zsh, etc. Those are all shells that interpret one command at a time, allow for interactive use (which is pretty easy since there is no pre-compiling done), etc. Perl isn't a shell -- it's strictly a scripting language, there is a bunch of preprocessing and compiling done before actually running the script, etc.

So you either have to use perl's command line switch to run code from the command line like so:

perl -e 'your code goes here' 
perl -E 'your code goes here' # This enables Perl 5.10 features
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Or you have to create a Perl script as toolic and Davido have already mentioned. For example:

#!/usr/bin/perl
use feature ":5.10"; # Use all new features in Perl 5.10
use strict;
use warnings;   
# Your code goes here here
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