Test

class Result extends Exception {
    public int value;
    public Result(int value) {
        this.value = value;
    }
}

abstract class Function {
    abstract public void apply(int input) throws Result;
    public final Function compose(Function other) {
        Function self = this;
        return new Function() {
            public void apply(int input) throws Result {
                try {
                    other.apply(input);
                } catch (Result r) {
                    self.apply(r.value);
                }
            }
        };
    }
}

class Square extends Function {
    public void apply(int x) throws Result {
        throw new Result(x * x);
    }
}

class TimesTwo extends Function {
    public void apply(int x) throws Result {
        throw new Result(2 * x);
    }
}

class Main {
  public static void main(String[] args) {
    Function f = new Square().compose(new TimesTwo()).compose(new Square());
    try {
      f.apply(2);
    } catch(Result r) {
      System.out.println(r.value);
    }
  }
}