C#

OriginalGriff wrote:

If she talks with a Lisp, that might be a problem for the OP...

double a = new Func<double>(delegate() { 2 + 2; });

DTBase<double> a = new DTFunc<double>(delegate() { 2 + 2; });
Console.WriteLine(a.Call); // Output 4
a = (DTVar<double>)5; // Conversion needed because DTBase<double> is an abstract class.
Console.WriteLine(a.Call); // Output 5
// Equivalent of "1 + 1 = X", where DTEquation calculates "x".
DTBase<double> a = new DTEquation((DTVar<double>)1, new DTOperand[] { new DTOperand(MathOp.Add, (DTVar<double>)1) });
Console.WriteLine(a.Call); // output 2

DTFunc<double, string> f = new DTFunc<double, string>(
                a =>
                {
                    string r = "";
                    while (a.Count > 0)
                    {
                        r += a.Call + ", ";
                    }
                    return r.Length > 0 ? r.Substring(0, r.Length - 2) : r;
                }
            );

            for (int i = 0; i <= 10; ++i)
                f.Args.Add = i;

            Console.WriteLine(f.Call);