Variant path types for scalable extensibility

@article{polymorphism-ooplsa2007,
   address = {New York, NY, USA},
   apice = {PolymorphismOoplsa2007},
   author = {Igarashi, Atsushi and Viroli, Mirko},
   doi = {10.1145/1297027.1297037},
   editor = {Gabriel, Richard P. and Bacon, David F. and Videira Lopes, Cristina and Steele, Jr., Guy L.},
   isbn = {978-1-59593-786-5},
   issn = {0362-1340},
   journal = {ACM SIGPLAN Notices},
   keywords = {Generics, parametric polymorphism, variant types, Featherweight Java},
   note = {Proceedings of the 22nd annual ACM SIGPLAN Conference on Object Oriented Programming Systems, Languages and Applications (OOPSLA '07), Montreal, Quebec, Canada},
   number = 10,
   pages = {113--132},
   publisher = {ACM},
   title = {Variant path types for scalable extensibility},
   volume = 42,
   year = 2007
}