Cue the smug Common Lisp weenies...

Oh, wait, that's me :-)

This is a nice illustration of the expression problem, which the article itself points out toward the end. Multiple dispatch is a language-level way to solve it. Crafting Interpreters [1] has a very approachable Java-based chapter that also covers these patterns in detail.

[0] https://en.wikipedia.org/wiki/Expression_problem

[1] https://craftinginterpreters.com/representing-code.html

if only programmers cared about functionality as much as syntax we'd be living in a lisp heaven

As I know C++ now allows multiple dispatch for std::variant: https://en.cppreference.com/w/cpp/utility/variant/visit2.htm....

And std::variant is now a better choice for cases like in the article above, where previously inheritance was used to represent a closed set of possible subtypes.

Would have been nice to mention that it's one thing that Julia seem to have gotten right.

Thanks for posting this!

Just a quick note that this post is the first in a series: see https://eli.thegreenplace.net/tag/multiple-dispatch for the full series