Roman Numeral Kata in Clojure

roman-num-final.clj

; The big change in logic happens at 5. You can use nested if statements to solve the kata up to 5.  
; After that, its best to define the roman numerals and their numbers in pairs, and pull from that.

(def pairs [[10 "X"][9 "IX"][5 "V"] [4 "IV"] [1 "I"]])

(defn roman [n]
  (loop [n      n
         result ""
         pairs  pairs]
    (if (< n 1)
      result
      (let [[num-in-pair roman-numeral] (first pairs)]
        (if (> num-in-pair n)
          (recur n result (rest pairs))
          (recur (- n num-in-pair) (str result roman-numeral) pairs))))))