sub nodes {
  my ($name, $ref, $path) = @_;
  if (ref $ref eq "ARRAY") {
    nodes($name, $ref->[$_], [@$path, ["array", $_]]) for 0..$#$ref;
  }
  elsif (ref $ref eq "HASH") {
    nodes($name, $ref->{$_}, [@$path, ["hash",$_]]) for sort keys %$ref;
  }
  else {
    print $name;
    for my $p (@$path) {
      print $p->[0] eq "array" ? "->[$p->[1]]" : "->{$p->[1]}"
    }
    print qq/ = "$ref";\n/;
  }
}
nodes(q/$a/, $a, []);