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Exit the looping loop in Clojure

I would like to exit the loop below and return best-min-move when line 10 evaluates to true. I scanned the output using print statements, and when line 10 does evaluate to true, it finds the data I'm looking for, but keeps repeating. In Clojure, is there a way to stop the loop when the statement evaluates to true? Or should I be using something other than looping over?

(defn minimax [board max-mark min-mark depth best-score] 
  (loop [board board
     max-mark max-mark
     min-mark min-mark
     depth depth
     best-score best-score]
  (if (= best-score (best-min-score board max-mark min-mark depth))
   (best-max-move board max-mark min-mark depth)                     
   (do                                                               
      (if (= best-score (best-min-score board min-mark max-mark depth))
       (best-min-move board min-mark max-mark depth)              
       (recur 
         (b/make-move-on board (remaining-scores board max-mark min-mark depth) max-mark)                
           min-mark 
           max-mark 
           (inc depth) 
           (dec best-score)))))))
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ABOUT loop

  • It's not loop

    that loops: it recur

    .
  • loop

    is that let

    which forms the point recur

    .
  • You cannot and cannot break out of the loop: it recur

    breaks you into one.

loop

is equivalent to setting up and calling an anonymous function. for example

(loop [n 5, s "Hello, world!"]
  (if (zero? n)
    (first s)
    (recur (dec n) (rest s))))

... is equivalent

((fn [n s]
  (if (zero? n)
    (first s)
    (recur (dec n) (rest s))))
 5 "Hello, world!")

With some loss of performance, it loop

could have been written as a macro that performs the above conversion.

As for your code:



There are six undefined functions here. To clean up compilation, we

(declare best-min-score 
         best-max-move
         best-min-move
         best-max-move
         make-move-on
         remaining-scores)

There are also two redundant forms. They do no active harm, but hide the code.

  • loop

    not required: the function itself is a suitable target for recur

    .
  • do

    does nothing: it includes one form.

Your function boils down to

(defn minimax [board max-mark min-mark depth best-score] 
  (if (= best-score (best-min-score board max-mark min-mark depth))
    (best-max-move board max-mark min-mark depth)
    (if (= best-score (best-min-score board min-mark max-mark depth))
      (best-min-move board min-mark max-mark depth)              
      (recur 
       (make-move-on board (remaining-scores board max-mark min-mark depth) max-mark)                
       min-mark 
       max-mark 
       (inc depth) 
       (dec best-score)))))

While any of the undefined functions can be repeated, the best option is best-min-move

.

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