[
      'note',
          [
            'shopping',
            [
              'item'
            ]
          ]
        ];

##</code><code>##

    [
          'note',
          [
            'shopping',
            [ item => 'bread' ],
            [ item => 'butter' ],
            [ item => 'beans' ],
            ]
        ];

##</code><code>##

use strict;
use warnings;

use Data::Rmap qw(:all);

my $initial =
  [
    note =>
      [
	shopping =>
	  [ 'item' ]
	 ]
     ];

use Data::Dumper;
my ($dump) = rmap_array {
  
  # If we get an arrayref whose first element is 'shopping'
  if ($_->[0] eq 'shopping') {
    my @item;
    # build a list of shopping items
    for my $item qw(bread butter beans) {
      push @item, [ item => $item ];
    }
    # create a new array with those items
    my $newdata = [ shopping => \@item ];
    # return immediately with new data, not visiting children
    # of this array
    cut($newdata)
  } else {
    # if the arrayrefs first element is not 'shopping'
    # then simply pass it through
    $_;
  }

  } $initial ;

warn Dumper($initial, $dump);