gistfile1.java

 // Representation of int32
class EInt32 extends EObject {
   static final long MIN_INT = Integer.MIN_VALUE, MAX_LONG=Long.MAX_VALUE;
   int value;
   ENumber plus(EObject rhs) { return rhs.r_plus(value); }
   ENumber r_plus(int lhs) {  
        long ret = lhs + this.value;
	if(((ret + MIN_INT)  & MAX_LONG) <= 0xFFFFFFFFL)
		return new EInt32((int)ret);
	else      
		return new EBig(ret);
   }

   // and others ... 
}