sub build_para
{
    return $handlers{'para'}->(join "" => map { $handlers{$_->[0]}->($_->[1]) } @{$_[0]});
}

##</code><code>##

my @test_data_2 = ( 'para', [
    ['none', 'The quick brown '],
    ['bold', 'fox'],
    ['none', ' jumped '],
    ['ital', 'over'],
    ['none', ' the lazy '],
    ['bold', 'dog'],
    ['none', '.']
    ]
);

sub build_HTML {
    join "" => map {
        (ref($_->[1]) eq "ARRAY") ?
            $handlers{$_->[0]}->(build_HTML(@{$_->[1]}))
            :
            $handlers{$_->[0]}->($_->[1])
    } ref($_[0]) ? @_ : ([ @_ ]);
}

print build_HTML(@test_data_2);

##</code><code>##

*build_para = curry(\&build_HTML, 'para');
print build_para(\@test_data);