Wholesale replacement of specialized classes may involve the ability to replace the auto specialization of a generic class may not be used at all and instead, a completely different, hand-written, class when the class is specialized for particular type parameterizations, according to some embodiments. The replacement class may have the same interface as the generic or auto specialized version, but it may have a completely different representation and/or implementation. A runtime environment may load the alternate version of the class, based on information identifying the alternate version, whenever the particular specialization is instantiated. The runtime may not have to load the generic or auto specialized version of the class when using the alternate version of the class.