Yes, good point. This in fact what I've done previously in an application that was dealing with monetary values. They were basically fixnums with a unit piggy

Yes, good point. This in fact what I've done previously in an application that was dealing with monetary values. They were basically fixnums with a unit piggybacked on, plus some money-specific operations. The money type should be compatible with generic interfaces so existing sorting and aggregation functions, for example, can directly on them.