1. A non-transitory, computer-readable storage medium storing program instructions that when executed on a computing device cause the computing device to perform: identifying, in a class file, a class name comprising a structural description describing a new class identified by the class name, wherein the structural description comprises information identifying a generator function and one or more parameters for the generator function; executing the generator function identified by the structural description, wherein said executing comprises providing the one or more parameters identified by the structural description as input to the generator function; generating the new class based, at least in part, on results from said executing the generator function, wherein the new class is not loadable prior to said generating; identifying another structural description, wherein the other structural description comprises information identifying another generator function and one or more other parameters for the other generator function; and determining whether the structural description and the other structural description represent two equivalent classes based, at least in part, on a comparison between the structural description and the other structural description and a comparison between the one or more parameters and the one or more other parameters.