package My::Hadoop::Example::Wordcount;
    use Moose::Role;

    sub map 
    { 
        my ($self,$line) = @_;
        my @words = split( /\W+/, $line);
        $self->emit( $_ => 1 ) for @words;
    }
    sub reduce 
    { 
        my ( $self, $key, $value_iterator) = @_;
        my $sum = 0;
        while( $value_iterator->has_next() ) 
        { 
            my $value = $value_iterator->next();
            $sum += $value;
        }
        $self->emit( $key, $sum );
    } 
    sub combine 
    { 
        my ( $self, $key, $value_iterator) = @_;
        my $sum = 0;
        while( $value_iterator->has_next() ) 
        { 
            my $value = $value_iterator->next();
            $sum += $value;
        }
        $self->emit( $key, $sum );
    } 

    package My::Hadoop::Example::Wordcount::Mapper;
    use Moose;
    with Hadoop::Streaming::Mapper,   My::Hadoop::Example::Wordcount;

    package My::Hadoop::Example::Combiner::Wordcount::Mapper;
    use Moose;
    with Hadoop::Streaming::Combiner, My::Hadoop::Example::Wordcount;

    package My::Hadoop::Example::Wordcount::Reducer;
    use Moose;
    with Hadoop::Streaming::Reducer,  My::Hadoop::Example::Wordcount;

    1;

##</code><code>##

  #!/usr/bin/perl
  use My::Hadoop::Example;
  My::Hadoop::Example::Mapper->run();

##</code><code>##

  #!/usr/bin/perl
  use My::Hadoop::Example;
  My::Hadoop::Example::Combiner->run();

##</code><code>##

  #!/usr/bin/perl
  use My::Hadoop::Example;
  My::Hadoop::Example::Reducer->run();  

##</code><code>##

  hadoop                                     \
      jar $streaming_jar_name                \
      -D mapred.job.name="my hadoop example" \
      -input    my_input_file                \
      -output   my_output_hdfs_path          \
      -mapper   my_mapper                    \
      -combiner my_combiner                  \
      -reducer  my_reducer