use strict;
use warnings;

use Data::Rmap qw(:all);

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

use Data::Dumper;

# build a list of shopping items ** for reuse **
my @shopping_items;
for my $item qw(bread butter beans) {
    push @shopping_items, [ item => $item ];
}

my ($dump) = rmap_array {
 
  # If we get an arrayref whose first element is 'shopping'
  if ($_->[0] eq 'shopping') {
    # Make the second element the shopping list
    $_->[1] = [ @shopping_items ];
    # No need to drill down any further
    cut($_);
    
  } else {
    # if the arrayrefs first element is not 'shopping'
    # then simply pass it through
    $_;
  }

  } $initial;

warn Dumper($initial, $dump);