CODEWITHSUNDEEP
recursionclojure
ttncrch
ttncrch

Reputation: 7253

Wrong argument number to recur function

I'm a beginner with functional programming and I try to pretty print a maze.
Here is my function

(defn pprint-maze
  [arr row col]
  (loop [coll arr idx 0]
    (match [idx]
      [(_ :guard #(= (mod idx col) 0))] (println "") ; write a \n
      :else (print "-"))                       ; write a wall
    (when (next coll)
      (recur (next coll) (inc idx)))))

My function takes the collection and the size of the maze and for now, just print a dash and a \n at the end of the row. The problem I've it's : Exception in thread "main" clojure.lang.ArityException: Wrong number of args (1) passed to: core/pprint-maze/fn--4873/fn--4874

I think the function pointed out is my loop function, and the problem is related to match (because when I comment the match block, everything work). I think that match try to call the loop function with nil as argument (the return of the println function).

How to solve that ?

Upvotes: 0

Views: 88

Answers (1)

amalloy
amalloy

Reputation: 91837

The function passed to :guard should take exactly one argument, the value being guarded. Your function takes zero arguments.

Upvotes: 7

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