sub munge_data {
    my($data) = @_;
  # temp hack
  use Data::Dumper; warn Dumper($data);
    ... # do munging
  }
  ...
$VAR1 = [
          bless( do{\(my $o = 63036880)}, 'Math::GMP' ),
          bless( do{\(my $o = 63024960)}, 'Math::GMP' ),
          bless( do{\(my $o = 63021408)}, 'Math::GMP' )
        ],

##</code><code>##

% cat ~/.dataprinter
use_prototypes = 0
index = 0
align_hash = 0
hash_separator = ' => '
colored = 0
begin filter Math::GMP
    $ddp->unsee($obj); "z_$obj";
end filter

% perl -MDDP -MMath::GMP -we '
  $val = 1;
  $zval = Math::GMP->new(1);
  p [$val, $val, $zval, $zval];
'
[
    1,
    1,
    z_1,
    z_1
]
%