sub process {
  my $node = shift;
  if (my $reftype = ref($node)) {
    return process_array($node) if $reftype eq 'ARRAY';
    return process_hash($node) if $reftype eq 'HASH';
    die "invalid node type: $reftype";
  } else {
    return process_scalar($node);
  }
}

process({ 'a' => '1', 'b' => [ '2' ],  'c' => { 'd' => '3' } });

##</code><code>##

package Local::MyComp::Map;

sub new { ... }
sub get { ... }
sub set { ... }
sub keys { ... }

etc. etc.

##</code><code>##

  if (my $reftype = ref($node)) {
    if (blessed($node) && $node->isa(Local::MyComp::Map) {
      process_map($node);
    } 
  ...