use JSON;
%HoA = ('foo' => [1,2,3], 'bar' => ['a','b','c']);
print "plain:\n".JSON->new->encode(\%HoA)."\n";
print "pretty:\n".JSON->new->pretty->encode(\%HoA);

##</code><code>##

plain: {"foo":[1,2,3],"bar":["a","b","c"]}
pretty: {
   "foo" : [
      1,
      2,
      3
   ],
   "bar" : [
      "a",
      "b",
      "c"
   ]
}

##</code><code>##

{
   "foo" : [1,2,3],
   "bar" : ["a","b","c"]
}