public class GnappoProduct {

private static class SchemeExpressionPower implements SchemeExpression {

private SchemeExpression exp1; private SchemeExpression exp2; public SchemeExpressionPower(SchemeExpression expr1, SchemeExpression expr2) {

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exp1=expr1; exp2=expr2;

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} public SchemeValue evaluate(SchemeEnvironment env) throws SchemeException {

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return SchemeFactoryManager.instance().create("SchemeExpressionInt",

((int)(Math.pow(exp1.evaluate(env).asInt(),exp2.evaluate(env).asInt())))).evaluate(env);

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} public void prettyPrint(PrintStream out) {

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out.print("(pow "); exp1.prettyPrint(out); out.print(" "); exp2.prettyPrint(out); out.print(")");

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}

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}

/**

• @param args
• @throws SchemeException

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*/

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public static void main(String[] args) throws SchemeException {

// TODO Auto-generated method stub SchemeFactoryManager fm = SchemeFactoryManager.instance(); fm.put("pow", new SchemeFactory() {

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public SchemeExpression create(Object... args) {

return new SchemeExpressionPower((SchemeExpression)args[0],(SchemeExpression)args[1]);

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}

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}); 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));

}

}