Pizza

Pizza was a short-lived experimental version of Java developed in the early 2000s. It extended Java by adding

generics (parametric polymorphism)
function pointers (first-class functions]
class cases and pattern matching (algebraic types]

The designs of Pizza strongly argued that the usual process of down-casting should be replaced by parametric polymorphism. Most of the work on that eventually influenced the design of Java generics, and ultimately Scala.

References

Martin Odersky and Philip Wadler. 1997. Pizza into Java: translating theory into practice. In Proceedings of the 24th ACM SIGPLAN-SIGACT symposium on Principles of programming languages (POPL '97). Association for Computing Machinery, New York, NY, USA, 146–159. DOI: https://doi.org/10.1145/263699.263715

@inproceedings{10.1145/263699.263715,
author = {Odersky, Martin and Wadler, Philip},
title = {Pizza into Java: Translating Theory into Practice},
year = {1997},
isbn = {0897918533},
publisher = {Association for Computing Machinery},
address = {New York, NY, USA},
url = {https://doi.org/10.1145/263699.263715},
doi = {10.1145/263699.263715},
booktitle = {Proceedings of the 24th ACM SIGPLAN-SIGACT Symposium on Principles of Programming Languages},
pages = {146–159},
numpages = {14},
location = {Paris, France},
series = {POPL '97}
}