Exercises: Add exercises for pattern matching chapter

[lritter79]

Complete the following REQUIRED checkboxes:

• I have thoroughly read and understand The Odin Project Contributing Guide
• The title of this issue follows the location for request: brief description of request format, e.g. Exercises: Add exercise on XYZ

The following checkbox is OPTIONAL:

• I would like to be assigned this issue to work on it

---

1. Description of the Feature Request:

The chapter on pattern matching throws a lot at you. I think it could help to add some exercises with solutions to practice before the project step.

2. Acceptance Criteria:

• Add a folder with problems related to pattern matching in Ruby to solve
• Add a rspec file for testing against
• Add a file with the solutions already made

3. Additional Information:

[JoshDevHub]

Hello @lritter79 and sorry for the slow reply. Our exercise repos aren't always frequently looked at.

I'm okay with this idea in the abstract, but I'm not sure what a concrete implementation would look like. What would a hypothetical exercise look like? And what would a test for it look like? I probably want to look at some examples of what you have in mind.

A big challenge with this I think is that pattern matching isn't strictly required to solve anything--it's just another option. This presents a problem for TDD though because tests care about behavior, not implementation. RSpec is designed to check that a learner has solved a problem, not that they've solved that problem using specific methods. You can of course just go on faith that learners are using pattern matching to solve the problems, but that feels slightly bad to me.

[lritter79]

I'm okay with this idea in the abstract, but I'm not sure what a concrete implementation would look like. What would a hypothetical exercise look like? And what would a test for it look like? I probably want to look at some examples of what you have in mind.

Sure so my idea for an exercise would be to make the learner fix buggy code: write like a dozen or so functions that use pattern matching, write tests that run against them, except every test fails from the start. Let the learner reflect on the lessons they e learned in the chapter to see why each function isnt working correctly.

As an example, lookat this code:

arr = [1, 2, 3, [4]]

case arr
in [_, _, [3, 4]]
  puts :match
end

This fails off the bat because we want 3 and 4 to be in a nested array, it’s just a details that’s off. Let me know what you think.

[JoshDevHub]

Okay cool! The buggy code idea is very interesting.

I'll bring it to the team at our next meeting and see what people think about it.