Getting Clojure

Function Specs

So far we’ve been treating clojure.spec as a general-purpose library for ensuring that our data looks the way it should. And so it is. But think about how useful it would be during development to have a way to automatically do some spec matching at critical points in your code. For example, wouldn’t it be great if you could write a spec for the arguments of a function and have that spec checked each time the function is called?

We could do this by taking advantage of function pre and post conditions:

;; Register a handy spec: An inventory is a collection of books.

(s/def :inventory.core/inventory
  (s/coll-of ::book))


(defn find-by-title
  [title inventory]
  {:pre [(s/valid? ::title title)
 (s/valid? ::inventory ...