cast-tastic.clj

(defn palindrome? [coll]
      (= coll
         (reverse coll)))

(defn n-digit-ints [n]
      (range (expt 10 (- n 1))
             (expt 10 n)))

(defn p4 [n]
      (let [choices (for [a (reverse (n-digit-ints n)),
                          b (reverse (n-digit-ints n))]
                         (* a b))]
        (apply max (->> choices                  ; choices -> seq of ints 
                        (map str)                ; -> convert to strings
                        (map #(apply vector %))  ; -> convert to vectors
                        (filter palindrome?)     ; select just the palindromes 
                        (map #(apply str %))     ; -> back to strings
                        (map #(Integer. %))))))  ; -> back to ints

Some time ago I came across this: http://www.rs.io/euler-4-in-clojure/ :-)