I don't really get what the author is claiming... I would have code his `if-mathch` in a simpler way in clojure: (case (f data-structure) 0 (do-some

I don't really get what the author is claiming... I would have code his `if-mathch` in a simpler way in clojure: (case (f data-structure) 0 (do-something) 1 (do-something-else) (do-default)) Where `f` can be a function defined in a protocol or a multimethod, so you can actually implement your own `f` for any data structure you like. Now, what I am missing ?