How to create index on JSON field in Postgres?

Question

In PostgreSQL 9.3 Beta 2 (?), how do I create an index on a JSON field? I tried it using the -> operator used for hstore but got the following e

Answer 1

Found:

CREATE TABLE publishers(id INT, info JSON); 
CREATE INDEX ON publishers((info->>'name'));

As stated in the comments, the subtle difference here is ->> instead of ->. The former one returns the value as text, the latter as a JSON object.