There is a PR up for '|' union, '&' intersection, and '^' symmetic difference methods added to Set and SortedSet:Set dgm operations by merscwog · Pull Request #1915 · apache/groovy · GitHub
The most concise use of Set operations in a general computer language is probably the python section of them in Rosetta Code:Set - Rosetta Code This would bring groovy into as close of parity that operator overloading allows at the moment. There are a bunch of questions in my mind concerning this proposed addition: I'm not sure they are strictly needed. They might not be implemented in the PR as generically enough as possible or desired -- might want to have them work on Collections/Iterables as well. Maybe explicit named methods should be added as well. Any feedback is welcomed. -Spencer
