Referring to function pointer in definition

factorial

-----
Dart
-----

main() {
	var factorial = (n) {
		if(n == 0)
			return 1;
		return n * factorial(n - 1);
	};
}

// error: line 2 pos 6: initializer of 'factorial' may not refer to itself


-----
C#
-----

class Program {
	static void Main() {
		Func<int, int> factorial = delegate(int n) {
			if(n == 0)
				return 1;
			return n * factorial(n - 1);
		};
	}
}

// (6,24): error CS0165: Use of unassigned local variable 'factorial'

-----
D
-----

void main() {
	auto factorial = (int n) {
		if(n == 0)
			return 1;
		return n * factorial(n - 1);
	};
}

// (5): Error: undefined identifier factorial



-----
Dart
-----

main() {
	var factorial;
	factorial = (n) {
		if(n == 0)
			return 1;
		return n * factorial(n - 1);
	};
}

// Works

-----
D
-----

void main() {
	int delegate(int) factorial;
	factorial = (int n) {
		if(n == 0)
			return 1;
		return n * factorial(n - 1);
	};
}

// Works