ISBN-13 validation

isbn13.clj

(defn isbn13? [isbn13]
  (let [nums (map #(Integer/parseInt %) (re-seq #"\d" isbn13))
        first-nums (butlast nums)
        sum (->> first-nums
                 (map vector (cycle [1 3]))
                 (map (partial apply *))
                 (reduce +))        
        last-num (last nums)]
    (= last-num
       (-  10 (mod sum 10)))))

(comment
  
  (map isbn13? ["978-0-306-40615-7" "978-0-306-40615-2"])
  ;; (true false)
  
  )

I like the let idiom. Makes me want a "where" clause like Haskell has. :) And ->> reminds me of |> in F# (the pipeline operator). Thanks for the implementation.