If you can use the map function from collections and if you understand why function with one argument has the following signature[1]: Function1 [-T1, +R]

If you can use the map function from collections and if you understand why function with one argument has the following signature[1]: Function1 [-T1, +R] Then you should be fine [1] Explanation here: http://stackoverflow.com/questions/5277526/real-world-examples-of-co-and-contravariance-in-scala/5279656#5279656 http://stackoverflow.com/questions/5277526/real-world-exampl...