public class GnappoProduct {
	
	private static class SchemeExpressionPower implements SchemeExpression {
		private SchemeExpression exp1;
		private SchemeExpression exp2;
		public SchemeExpressionPower(SchemeExpression expr1, SchemeExpression expr2) {
			exp1=expr1;
			exp2=expr2;
		}
		public SchemeValue evaluate(SchemeEnvironment env) throws SchemeException {
			return SchemeFactoryManager.instance().create("SchemeExpressionInt", 
			        ((int)(Math.pow(exp1.evaluate(env).asInt(),exp2.evaluate(env).asInt())))).evaluate(env);
		}
		public void prettyPrint(PrintStream out) {
			out.print("(pow ");
			exp1.prettyPrint(out);
			out.print(" ");
			exp2.prettyPrint(out);
			out.print(")");
		}
	}

	/**
	 * @param args
	 * @throws SchemeException 
	 */
	public static void main(String[] args) throws SchemeException {
		// TODO Auto-generated method stub
		SchemeFactoryManager fm = SchemeFactoryManager.instance();
		fm.put("pow", new SchemeFactory() {
			public SchemeExpression create(Object... args) {
				return new SchemeExpressionPower((SchemeExpression)args[0],(SchemeExpression)args[1]);
			}
		});
		SchemeExpression power = fm.create("pow",fm.create("SchemeExpressionInt",2),fm.create("SchemeExpressionInt",4));
		power.prettyPrint(System.out);
		System.out.println();
		System.out.print(power.evaluate(null));

	}
	


}