[goodthink]

Reading this book brought me a better understanding of "the expression problem" and the use of the visitor pattern as its solution. This led me to (finally) grok the use of Class _Heirarchy_ Inheritance[0] as a solution not requiring visitors. In Newspeak[1], classes can contain nested classes, so when you subclass a class, you inherit the nested classes as well. This blog post discusses the same feature affording Free Object Algebras [2].

[0] https://blog.bracha.org/primordialsoup.html?snapshot=Amplefo... [1]https://newspeaklanguage.org [2]https://blog.bracha.org/primordialsoup.html?snapshot=Amplefo...