"Expression<Func<int, int>> expr = a => a + 3;
Console.WriteLine(expr); // prints "a => Add(a, 3)"
Func<int, int> func = expr.Compile(); // LCG's an MSIL method from the expr
Console.WriteLine(func(4)); // prints "7""
(Don Box)

You will have to rewrite computer science curicullum to understand this stuff. Go back to basic and learn LISP.