Make it: interface Addable<RHS, Result> { Result add(RHS other); } The problem is hardly new though. Groovy is very Java-like and has operator overloa

Make it: interface Addable<RHS, Result> { Result add(RHS other); } The problem is hardly new though. Groovy is very Java-like and has operator overloading: http://groovy-lang.org/operators.html#Operator-Overloading http://groovy-lang.org/operators.html#Operator-Overloading