my $array_ref = [
  { foo=> 1, herp => 'a'},
  { bar => 2, derp => 'b'},
  { baz => 3, burp => 'c'},
];

# to iterate
foreach my $h (@$array_ref) {
  foreach $k (keys %$h) {
    ++$h->{$k}; # note ++ "increments" strings as well
  }
}