Question

Why doesn’t this compile? I suppose there are ways to work around this; just curious.

Thanks!

    static void Main(string[] args)
    {
        Func<int, int> f_int = n => n * n;
        Func<int, double> f_double = (Func<int, double>)f_int;
    }

Answer 1

Generics don’t have this type of variance; not now, and not (for value-types such as int/double) in 4.0. Simply, f_int doesn’t return a double. The best you can do is:

Func<int, double> f_double = i => f_int(i);

which has an implicit conversion from int to double in the returned value.