Clojure - Too many arguments for function called with apply

Question

I'm currently doing the tutorial examples for clojure, and one of them involves calling a function 3 times on multiple arguments, my code looks like this:

(defn triplicate [f] (dotimes [n 3] (f)))

(defn triplicate2 [f & args] (
   (triplicate #(apply f args))))

(triplicate2 #(println %) 1)

it works with 1 functiona and 1 rest parameter, but when I call it like this:

(triplicate2 #(println %) 1 3 4)

I get this error

ArityException Wrong number of args (2) passed to: 
user/eval1198/fn--1199  
clojure.lang.AFn.throwArity (AFn.java:429)

Am I thinking diferently from what I should?

Help !

dpassen · Accepted Answer · 2019-11-17 18:11:02Z

3

The function you are passing to triplicate2

#(println %)

is expecting one argument and you are passing one in the working example and three in the non-working example.

Since println is already variadic, you can just call

(triplicate2 println 1)

and

(triplicate2 println 1 3 4)

answered Nov 17, 2019 at 18:11

dpassen

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2 Comments

getpo.st Over a year ago

that rerturns 1 3 4 1 3 4 1 3 4 instead of 111 333 444 and NullPointerException user/triplicate2 (form-init3721418806447969988.clj:3)

dpassen Over a year ago

Your triplicate2 function invokes the result of triplicate. You have one too many parens.

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