package PrettyPrinting; # the .pm file extension is required

require Exporter; # load at run time
our @ISA = qw(Exporter); # inherits from the Exporter package
our @EXPORT = qw(print_tree); # export by default
our @EXPORT_OK = qw(print_indent print_scalar); # export by request

my $depth = -1;

sub print_indent {
  my $spaces = ".  " x $depth;
  print $spaces, shift, "\n";
}

sub print_scalar {
  ++$depth;
  my $obj = shift;
  print_indent $obj;
  --$depth;
}

sub print_tree {
  my ($r_array) = @_;
  ++$depth;
  print_indent "(" . shift @{$r_array};
  foreach my $obj (@{$r_array}) {
    if (ref ($obj)) {
      print_tree($obj);
    }else{
      print_scalar($obj);
    }
  }
  print_indent ")";
  --$depth;
}
1; # the return value of the module, mandatory