Getting Clojure

Arguments with Wild Abandon

Multi-arity functions are fine for functions like greet, functions that might take one or two or some other definite number of arguments. But what if you want to write a function that can deal with a completely arbitrary number of arguments? The good news is that you can get this done with the strategic placement of an & in your argument list.

Here, for example, is a function that will take any number of arguments and print them all out:

(defn print-any-args [& args]
  (println "My arguments are:" args))

When someone calls print-any-args, the arguments show up in the args parameter—the one after the ampersand—as a collection. So if you call print-any-args like this:

(print-any-args 7 true nil)

you will see this: ...