#!perl -w
use strict;
use JSON::XS;

# Create a simple circular data structure:
my $output;
$output = ['foo'];
$output->[1] = $output;

my $json = JSON::XS->new->utf8->max_depth(100);
use Data::Dumper;
print Dumper $output;
print $json->encode($output);

__END__
json text or perl structure exceeds maximum nesting level (max_depth set too low?) at tmp.pl line 13.