use Data::Dumper;
$Data::Dumper::Deepcopy = 1;

my @a = qw/foo bar baz/;
my @last = (1);
push @last, { $_ => $last[-1] } foreach reverse @a;
print Dumper( $last[-1] ); # result


##</code><code>##

$VAR1 = {
          'foo' => {
                     'bar' => {
                                'baz' => 1
                              }
                   }
        };