Getting Clojure

This Is the Data You’re Looking For

To get a feeling for how clojure.spec works, let’s return to our book-store example and imagine that we’re writing code to process our familiar book maps, values that look like this:

{:title "Getting Clojure" :author "Olsen" :copies 1000000}

Further, imagine that we’re getting our book data from a not-terribly-reliable source, and we’ve decided that the first thing we need to do is validate that this value that claims to be a book is in fact a book-shaped value. Clearly we could write a function:

spec/inventory/src/inventory/core.clj

(defn book? [x]
  (and
    (map? x)
    (string? (:author x))
    (string? (:title x))
    (pos-int? (:copies x))))

While this does work, the code it by hand approach to validating ...