use strict;
use warnings;

my $r = 0;
$r = {
    rest => $r,
    first => 'c'
};
$r = {
    rest => $r,
    first => 'b'
};
$r = {
    rest => $r,
    first => 'a'
};

print join " ", value($r), scalar value($r);

sub value {
    my $self = $_[0];
    if (wantarray) {
        my @value;
        while ($self) {
            push @value, $self->{'first'};
            $self = $self->{'rest'};
        }
        return @value;
    }
    my $c;
    while ($self) {
        $c++;
        $self = $self->{'rest'};
    }
    return $c;
}