Take a look at Data::Dumper or Data::Dump (and many others of similar nature). Both of these modules define functions that iterate through arbitrarily deeply nested data structures — and they don't even require that they be purely hashes-of-hashes or arrays-of-arrays!

>perl -wMstrict -le
"my %ds = (
   X => [ { one => 1 },     { two => 2,  three => 3 }, ],
   Y => [ { fee => 'fie' }, { foe => 'fum' }, { foo => 'bar' }, ],
   );
 ;;
 use Data::Dumper;
 print Dumper \%ds;
"
$VAR1 = {
          'X' => [
                   {
                     'one' => 1
                   },
                   {
                     'three' => 3,
                     'two' => 2
                   }
                 ],
          'Y' => [
                   {
                     'fee' => 'fie'
                   },
                   {
                     'foe' => 'fum'
                   },
                   {
                     'foo' => 'bar'
                   }
                 ]
        };
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