[anonymoushn]

As an example of this, I've been working through Crafting Interpreters off and on. Chapter 5 consists mostly of discussion of the visitor pattern (is this the same thing as double dispatch?). The author notices that the amount of code that must be written to implement the design is so large that it's best to write a program to generate all of that code. I followed along as best I could, and at the end I wrote the equivalent code in my preferred language, which I've included in this comment:

  self[expr.type](self, expr)