roman-numeral.clj

(with-test                                                                                      
  (defn roman-numeral                                                                           
    [input]                                                                                     
    (loop [input input, acc 0, ]                                                                
      (if (empty? input)                                                                        
        acc                                                                                     
        (let [convert {"I" 1, "V" 5, "X" 10, "L" 50, "C" 100, "D" 500, "M" 1000, }              
              curr-num (convert (subs input 0 1))                                               
              op (if (and (not= 1 (count input))                                                
                          (< curr-num                                                           
                             (convert (subs input 1 2))))                                       
                   - +)]                                                                        
          (recur (subs input 1)                                                                 
                 (op acc curr-num))))))                                                         
  (are                                                                                          
      [a b] (= (roman-numeral a) b),                                                            
      "XIV" 14,                                                                                 
      "DCCCXXVII" 827,                                                                          
      "MMMCMXCIX" 3999,                                                                         
      "XLVIII" 48, ))