srecord ResolvableLASClass(LASClassLoader lasClassLoader, LASClassDef classDef) {
  Class get() {
    if (lasClassLoader == null)
      fail("Need LASClassLoader to define " + classDef.userGivenName);
    ret lasClassLoader.defineLASClass(classDef.finalClassName(),
      -> classDef.toBytes());
  }
}