Set operation aggregation

I am wondering whether elasticsearch has aggregations (other than script aggregation) to support set operations (e.g: union, subtract) like below:
Input:

{ "users": [ "mary", "john"] }
{ "users": [ "john", "alice"] }
{ "users": [ "bob"] }

Aggregated output:

{"allUsers": ["mary", "john", "alice", "bob"]}

It will be similar to Oracle DB's LISTAGG function but without duplicates (http://docs.oracle.com/cd/E11882_01/server.112/e41084/functions089.htm#SQLRF30030)