try this

use Tie::Judy;

tie %fruit_color, 'Tie::Judy';
[download]

A hash represents a set of key/value pairs:

my %fruit_color = ("apple", "red", "banana", "yellow");
[download]

You can use whitespace and the '=>' operator to lay them out more nicely:

my %fruit_color = (
    apple  => "red",
    banana => "yellow",
);
[download]

To get at hash elements:

$fruit_color{"apple"};           # gives "red"
[download]

You can get at lists of keys and values with keys() and values().

my @fruits = keys %fruit_color;
my @colors = values %fruit_color;
[download]

see also Re: need help with Tie::Judy

I'm trying to understand what is happen with the sample code LanX has provided...

The command tie %fruit_color, 'Tie::Judy'; ties the associative array* %fruit_color to the class. From this point on, when %fruit_color is used, instead of the default Perl behaviour, the implementation is handled by Tie::Judy which implements alternative methods to the default methods used by Perl. In this case it does the same thing in a different way.

Is that something like correct?

* I deliberately didn't refer to %fruit_color here as a hash because in this case it is a Judy Array which is not a hash but another example of the same type of storage.