How can I determine number of arguments to a function in Clojure?

Question

Given a function x in clojure how can I programatically get a count of the number of arguments?

eg:

(fn a [b c] ...) has has two arguments
(fn a [] ...)          


        

Answer 1

You could construct a function taking all arguments, putting them in a list and returning the count like so:

(defn arg-count [& rest] (count rest))
(arg-count) ;; 0
(arg-count 1 2 3) ;; 3