Wrong number of args (2) passed to: core/first

Question

I am new to Clojure and I have having some issues with iterating data.

The code I have written is below :

(defn save-monthly-targets
  "Parse Monthly Targets Data and Save"
  [monthlyTargets]
  (println "Save Monthly " monthlyTargets)
  (if (first monthlyTargets)
   (let [month (first monthlyTargets :month)
         year (first monthlyTargets :year)
         name (first monthlyTargets :name)]
        (do
            (println "Calling Save Method" month)
            (users/set-monthly-target month year name)
            (save-monthly-targets (rest monthlyTargets))))))

When I call the function:

(save-monthly-targets [
    {:month "May", :year "2021", :target "1200"},
    {:month "May", :year "2016", :target "1200"}
])

I get the wrong number of args error in the (if (first monthlyTargets) statement.

The exception is:

ArityException Wrong number of args (2) passed to: core/first clojure.lang.AFn.throwArity

Can someone point what is wrong here?

Thank you very much.

score 4 · Accepted Answer · answered Apr 08 '16 at 09:35

As the error states, you are passing two parameters to first e.g.

(first monthlyTargets :month)

when you want:

(let [month (:month (first monthlyTargets))
      ...])

you can match all the values at once using destructuring:

(let [{:keys [month year name]} (first monthlyTargets)
      ...])

Wrong number of args (2) passed to: core/first

1 Answers1