sub traverse(&$) {
    my( $code, $ref ) = @_;
    my $d;
    $d = {
        SCALAR => sub{
            my $code = shift; my $ref = shift;
            return $code->( @_, $$ref );
        },
        ARRAY  => sub {
            my $code = shift; my $ref = shift;
            map $d->{ ref $ref->[ $_ ] }->( $code, $ref->[ $_ ], @_, $_ ), 
                0 .. $#$ref;
        },
        HASH  => sub {
            my $code = shift; my $ref  = shift;
            map $d->{ ref $ref->{ $_ } }->( $code, $ref->{ $_ }, @_, $_ ), 
                keys %$ref;
        },
        REF  => sub{
            my $code = shift; my $ref = shift;
            return $d->{ ref $$ref }->( $code, $$ref, @_ );
        },
        CODE => sub{
            my $code = shift; my $ref = shift;
            return $d->{ '' }->( $code, "$ref", @_ );
        },
        ''  => sub{
            my $code = shift; my $ref = shift;
            return $code->( @_, $ref );
        },
    };
    return $d->{ ref $ref }->( $code, $ref );
}

traverse { print join ',', @_ } \%hash;