Polymorphic Dispatch Revisited

2023-07-03

In a previous post about polymorphic dispatch, I outlined Clojure's defprotocol and defrecord as 'the' way to do polymorphic dispatch.

While defprotocol and defrecord are used for polymorphic dispatch, a much more common and simple way to do it is with multimethods. I have a whole other post about multimethods here.

In that post you can see that multimethods generally take less code and are nice because they work well with maps. You can pass in a single object that maps to the dispatch value you want while also carrying any other data needed for the calculation. Using multimethods is also good because you aren't instantiating so many objects.

Overall, protocols and records/types are useful, but it's good to use maps and multimethods by default.