Algorithm::Loops's NestedLoops can handle this. 

use strict;
use warnings;

use Algorithm::Loops qw( NestedLoops );

my %data = (
   fruit  => [qw( apple pear     )],
   type   => [qw( farmed organic )],
   period => {
      20050824 => {
         to  => [ 'new york', 'london' ],
      },
      20050825 => {
         to  => [ 'auckland' ],
      },
   }
);

my $iter = NestedLoops([
   $data{fruit},
   $data{type},
   [ keys %{$data{period}} ],
   sub { $data{period}{$_[2]}{to} },
]);

my @expanded;
while (my @list = $iter->()) {
   my %row;
   @row{qw( fruit type period to )} = @list;
   push @expanded, \%row;
}

require Data::Dumper;
print(Data::Dumper::Dumper(\@expanded));

[download]

Update: Fixed typo in link.

In reply to Re: Expanding / flattening a structure by ikegami
in thread Expanding / flattening a structure by jaa

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