[v3] Extract Concepts from v2 exercise: Armstrong Numbers

[bobbicodes]

Extract the list of concepts required to solve the v2 Clojure exercise: Armstrong Numbers. For each concept, describe why it is required to solve the exercise. Keep in mind that an exercise can have multiple approaches (you can find community solutions here: https://exercism.io/tracks/clojure/exercises/armstrong-numbers/solutions). The goal of this task is to help determine the total list of concepts that make up Armstrong Numbers.

The list of concepts should be stored in the following document: reference/exercise-concepts/armstrong-numbers.md. Use this link to create a PR to add this document.

[bemself]

@porkostomus sorry to ask, what do we further need to do? I see in v3 you've already prepared a list of concept...

[bobbicodes]

Good question. I actually just filed this because I saw that's what everyone else was doing! But since I've taken a more comprehensive approach towards defining concepts (based on the official docs, Clojure Atlas, etc.) rather than extracting them from v2 exercises, which tbh do not really represent an ideal learning path.

This issue should simply serve as an example, should anyone at any time feel that a certain v2 exercise would be worth deconstructing. After all, there are 76 of them ;)

[bobbicodes]

As we are preparing for the launch of v3 this is becoming relevant. See #330.

The essence of this exercise is learning to use higher-order functions, specifically map and reduce.

1. The number must be split into its digits, either by division or string iteration
2. An exponent function must be created or called from Java Math library. If created, this will most likely involve a reduce.
3. This exponent function will need to be mapped onto the digits
4. reduce is used to "add them all up", the most basic use of the function.