Question

I want to create a closure (function generator) to raise a number to a power, without using a specific Clojure library to accomplish this task. Right now, I can do this with loop .. recur.

(defn exp1
 [in-num in-exp-multi]
 (loop [num in-num exp-multi in-exp-multi]
    (if (> exp-multi 1)
        (recur (* num in-num) (- exp-multi 1))
        num)))

I have tried using partial to raise the power, but am still stuck on the construct needed to repeat multiplying a number by itself some number of times. So, I am looking for an example of generating a function and applying it x number of times.

Edit:

The example was simply to solve a problem using loop .. recur. My desire is to solve this with a closure.

Answer 1

I can’t tell from your question precisely what you’re asking for, but maybe this?

(defn powers-of [exponent]
  (iterate #(* % exponent) 1))

(defn nth-power-of [exponent]
  (partial nth (powers-of exponent)))

((nth-power-of 5) 2) ;; returns 25

I think iterate is what you’re looking for based on your description; it creates a lazy seq of the function applied over and over to the seed.