Action dummyLambda = () => { Console.WriteLine("Hello World from a Lambda expression!"); };
 
// double y = square(25);
Func<double, double> square = x => x * x;
 
// double z = product(9, 5);
Func<double, double, double> product = (x, y) => x * y;
 
// printProduct(9, 5);
Action<double, double> printProduct = (x, y) => { Console.WriteLine(x * y); };
 
// var sum = dotProduct(new double[] { 1, 2, 3 }, new double[] { 4, 5, 6 });
Func<double[], double[], double> dotProduct = (x, y) =>
{
  var dim = Math.Min(x.Length, y.Length);
  var sum = 0.0;
  for (var i = 0; i != dim; i++)
    sum += x[i] + y[i];
  return sum;
};
 
// var result = matrixVectorProductAsync(...);
Func<double, double, Task<double>> matrixVectorProductAsync = async (x, y) =>
{
  var sum = 0.0;
  /* do some stuff using await ... */
  return sum;
};