Getting Clojure

Staying Out of Trouble

One of the surprising things about Clojure functions is that you can mix and match the variadic & into a multi-arity function if you are careful. Here’s us being careful:

(defn one-two-or-more
  ([a] (println "One arg:" a))
  ([a b] (println "Two args:" a b))
  ([a b & more] (println "More than two:" a b more)))

We just need to keep in mind that Clojure is sharp enough not to let us define a multi-arity function with overlapping arguments. For example, if we had written that last function as

;; Oh no!

(defn one-two-or-more
  ([a] (println "One arg:" a))
  ([a b] (println "Two args:" a b))
  ([& more] (println "More than two:" more)))

then we wouldn’t get past the Clojure compiler. The problem is ...