Implement new learning exercise: `Closures`

[bobbicodes]

This issue describes how to implement the closures learning exercise for the Clojure track.

Getting started

Please please please read the docs before starting. Posting PRs without reading these docs will be a lot more frustrating for you during the review cycle, and exhaust Exercism's maintainers' time. So, before diving into the implementation, please read up on the following documents:

• The features of v3.
• Rationale for v3.
• What are concept exercise and how they are structured?

Please also watch the following video:

• The Anatomy of a Concept Exercise.

Goal

The goal of this exercise is to teach the student how closures are used in Clojure.

This can simply be a port of the Coordinate transformation exercise.

Learning objectives

The student will gain a general understanding of:

• How function composition is used to share data across lexical scopes

Out of scope

Concepts

• higher-order-functions

Prerequisites

• basics

Resources to refer to

Functions - Clojure Guides

Representer

The Clojure Representer is currently being implemented and contributions are welcome.

Analyzer

The Clojure Analyzer is currently being implemented and contributions are welcome.

Implementing

To implement a concept exercise, the following files must be created:

languages
└── clojure
    └── exercises
        └── concept
            └── <SLUG>
                ├── .docs
                |   ├── instructions.md
                |   ├── introduction.md
                |   ├── hints.md
                |   └── after.md (optional)
                ├── .meta
                |   |── design.md
                |   └── Example.clj
                ├── <NAME>.clj
                └── <NAME>_test.clj

Help

If you have any questions while implementing the exercise, please post the questions as comments in this issue.