static void Main() { List <string> left = new List <string> { "Alice", "Charles", "Derek" }; List <string> right = new List <string> { "Bob", "Charles", "Ernie" }; EnumerableExtensions.CompareSortedCollections(left, right, StringComparer.CurrentCultureIgnoreCase, s => Console.WriteLine("Left: " + s), s => Console.WriteLine("Right: " + s), (x, y) => Console.WriteLine("Both: " + x + y)); }