FuncRecursion.java

package aoc;

public class FuncRecursion {

	static interface Func {
		int apply();
	}
	
	static class ReturnZero implements Func {
		@Override
		public int apply() {
			return 0;
		}
	}
	
	static class AddOne implements Func {
		
		private Func src;
		
		public AddOne(Func src) {
			super();
			this.src = src;
		}

		@Override
		public int apply() {
			return src.apply()+1;
		}
	}
	
	public static void main(String[] args) {
		
		Func x = new ReturnZero();
		
		for (int i = 0; i < 10; i++) {
			x = new AddOne(x);
		}
		
		System.out.println(x.apply());

	}

}