Question

I have a clojure function:

(defn f [arg1 arg2]
  ...)

I would like to test if arg1 and arg2 are numeric (only numeric types should pass – not numerically formatted strings). There are, of course, a whole bunch of ways to do this, but I’d like to do it as idiomatically as possible. Suggestions?

Edit: I know about :pre. Any comment on whether or not that is an appropriate/necessary way to handle this would be appreciated.

Answer 1

Pre-conditions can do that:

(defn test [arg1 arg2]
  {:pre [(number? arg1) (number? arg2)]}
  (+ arg1 arg2))

(test 1 2)
=> 3

(test 1 "2")
=> Assert failed: (number? arg2)

See http://clojure.org/special_forms#toc9 for docs.