Returning a function with the same signature as itself in C#

Question

In my application, I want a function that after doing some work, return a function with the same signature as itself, or null: Notice that there's nothing generic here, as all type are "static" (as in, the opposite of generic)

//type is not a C# keyword, but bear with me
type RecursiveType = Func<int, RecursiveType>;
RecursiveType currentStep; //something not null
var i = 0;
while (currentStep != null) {
    currentStep = currentStep(i);
    i += 1;
}

"currentStep" would be something like (this is an example. In the real case Foo::A executes some logic to decide which function it will return, and may or may not be itself)

class Foo {
    public static RecursiveType fun(int x) {
        if (x < 3) { 
            return Foo.A
        }
        else {
            return null;
        }
    }
}

Is this possible in C#?

Answer 1

You can declare a delegate type like this:

public delegate RecursiveType RecursiveType(int x);

Then this will compile:

RecursiveType currentStep = Foo.fun(1);
var i = 0;
while (currentStep != null)
{
    currentStep = currentStep(i);
    i += 1;
}

The delegate represents a function that accepts an int and returns a function of the same signature.