Covariance and Contravariance

CoAndContraVariance.cs

// Airplane = base class
// F16 = derived class

// covariance: can use MORE spesific type than originally specified
IEnumerable<F16> f16s = new List<F16>();
IEnumerable<Airplane> covariance = f16s;

// contravariance: can use LESS specific type than originally specified
Action<Airplane> airplanes = (target) => { Console.WriteLine(target.GetType().Name); };
Action<F16> contravariance = airplanes;
contravariance(new F16());