YAML::XS from CPAN (http://search.cpan.org/dist/YAML-LibYAML/lib/YAML/XS.pm). For example:

#!/usr/bin/perl -w
use strict;

package example;    # object definition

sub new {
    my $self = {};
    $self->{'data'} = pop;
    return bless($self);
}

sub getData {
    my $self = shift;
    return $self->{'data'}
}

package Main;

use YAML::XS;

my $eg = new example("Hello world!\n");
my $save = Dump $eg;    # object instance to yaml markup

# save yaml markup to file
open (EG, '>yaml.test') || die;
print EG $save;
close(EG);

$save = $eg = undef;    # clear variables

# now load yaml markup from file
open (EG, '<yaml.test') || die;
$save .= $_ while (<EG>);
close(EG);

# yaml markup back into object
$eg = Load $save;
print $eg->getData();   # proof!
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Dump and Load are the YAML::XS commands.

Or slightly shorter:

use strict;
use warnings;

package Example;

sub new {
    my $self = {};
    $self->{'data'} = pop;
    return bless($self);
}

package main;

use YAML qw(DumpFile LoadFile); # it will use YAML::XS if it installed
use Data::Dumper;

my $eg = Example->new("Hello world!");
my $save = DumpFile('test.yml', $eg);

my $rest = LoadFile('test.yml');

warn Dumper $rest;
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You actually have a couple of choices for YAML and Moose.

First is MooseX::Storage, which is a full fledged serialization framework which no only supports YAML, but also JSON and Storable and will handle both serializing to text or to a file.

If that is more then you really are looking for, then you might want to take a look at MooseX::YAML which works best with YAML::XS and will reconstruct your Moose object in the correct way using MooseX::Blessed::Reconstruct to do all the dirty work.

The major difference between these two modules being that MooseX::Storage handles reading and writing, while MooseX::YAML is really mostly just concerned with reading since you would basically just use plain old YAML to do the writing for you.