Y combinator (dynamic)

dynamicy.cs

using System;
public class C {
    public void M() {
            Func<Func<dynamic, dynamic>, dynamic> fd = x => x;
            dynamic Y = fd(f => fd(x => f(fd(y => x(x)(y))))(fd(x => f(fd(y => x(x)(y))))));
            Y(fd(f => fd(x => f(x))))(42);
    }
}