[v3] Implement new Concept Exercise: sets

[wneumann]

This issue describes how to implement the sets concept exercise for the Swift 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 the following documents:

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

Please also watch the following video:

• The Anatomy of a Concept Exercise.

Goal

This concept exercise should convey a basic understanding of how to work with Sets in Swift.

Things to teach

• Initializing empty sets
• Initializing sets from array literals
• Inserting and removing elements
• Testing for membership
• Iterating over a set
• Performing set operations

Things not to teach

• Hashable requirement for elements
• map, reduce, filter, etc.

Concepts

• sets
• set-operations

Prerequisites

• arrays

Resources to refer to

Hints

• Sets
• Set documentation

After

• Sets
• Set documentation

Representer

TBD

Analyzer

TBD

Implementing

See the Swift track implementation guide for guidance.

Help

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

[wneumann]

This is assigned to @HanaisMe. It'll be "officially" assigned once the permissions get set up properly.