1. A computer program product comprising one or more computer-readable media having thereon an executable module, the executable module comprising: a frozen object that is an instance of a type canonically described by a canonical type descriptor that conforms to a set of canonicalization rules; an auxiliary type descriptor that is not identical to the canonical type descriptor, but that also serves as a type descriptor for the frozen object, at least for some of operations that use type descriptors for the type; wherein the frozen object is directly or indirectly associated with the auxiliary type descriptor and the canonical type descriptor.