Add map and reduce concepts

[JaumeAmoresDS]

Added conceps for higher-order functions map and reduce

[github-actions]

Hello. Thanks for opening a PR on Exercism 🙂

We ask that all changes to Exercism are discussed on our Community Forum before being opened on GitHub. To enforce this, we automatically close all PRs that are submitted. That doesn't mean your PR is rejected but that we want the initial discussion about it to happen on our forum where a wide range of key contributors across the Exercism ecosystem can weigh in.

You can use this link to copy this into a new topic on the forum. If we decide the PR is appropriate, we'll reopen it and continue with it, so please don't delete your local branch.

If you're interested in learning more about this auto-responder, please read this blog post.

---

Note: If this PR has been pre-approved, please link back to this PR on the forum thread and a maintainer or staff member will reopen it.

[bobbicodes]

This is great, thanks! I'll probably only have minor suggestions

[bobbicodes]

I'm thinking maybe the introduction pages could be made smaller. Since the purpose of having a separate Introduction and About page is for the former to contain just enough to get them started, while the About pages are more comprehensive.

(This is more of a statement on how thorough you made them than a criticism)

[JaumeAmoresDS]

@bobbicodes would it be good like this? I removed the last two sections of each introduction.md, but kept them in about.md

[bobbicodes]

Yes, that's perfect :)

[bobbicodes]

While we are touching things related to these new concepts, it just occurred to me that the tree will be affected significantly due to their introduction. In other words, someone will need to go through the practice exercises in the root config.json and add map and/or reduce to the prerequisites and practices arrays to the exercises as appropriate.

I expect there to be a lot of relevant exercises.

This could be done in a later PR however. It's kind of a big job because you have to go through each one and decide whether the concept is essential to solving it.

[JaumeAmoresDS]

I might be able to do it, although I think it will take a bit of time. The thing is that I am not familiar with the exercises, since I did very few so far. I'm also a newbie in clojure, which makes it a bit more challenging, although this might not be an issue if I am guided through the PR review process.

[bobbicodes]

No worries, just thinking ahead :)

[JaumeAmoresDS]

@tasxatzial @bobbicodes do you think this PR could be merged? It contains concepts and exercises for map and reduce, which I believe would be very important to have in the clojure track?

[tasxatzial]

@JaumeAmoresDS I'll take a look at it later :)

[tasxatzial]

@JaumeAmoresDS Can you please format using one sentence per line in the introduction.md and about.md of the reduce concept? It's common practice around here.

Only these two files please because i already have a review in progress about everything else.

[tasxatzial]

This is the first pass of the review. Includes everything except the introduction.md and about.md from the reduce concept.

@JaumeAmoresDS Please take a look and let me know if there are questions.

[tasxatzial]

Given that you created this PR 1.5 year ago, please let me know if you are willing to go through couple rounds of review. If it's too much, I can merge right away and update it in a subsequent PR. No worries.

[JaumeAmoresDS]

@tasxatzial I applied your suggestions and changed about.md and introduction.md as requested. Please let me know if this would be ok.

[tasxatzial]

It seems that you've added extra empty lines. These aren't really needed because they will break paragraphs into multiple lines. That's not what we are after. We want to preserve the existing paragraphs and format the original file with one sentence per line, not the final rendered markdown file.