add sgf-parsing exercise

[oxe-i]

No description provided.

[oxe-i]

Tomorrow I'll improve the error handling of the generator and add a generator for word-count. I'll eventually add an exercise that requires the student to define macros/custom operators, but I'm still not sure which.

[keiravillekode]

In case you are about to test many exercises online:

I have noticed with past tracks, that if I complete all the Hard exercises before track launch, I won't receive the Difficult trophy even when the track launches. I need to complete at least one Hard exercise after the track launches.

[oxe-i]

In case you are about to test many exercises online:

I have noticed with past tracks, that if I complete all the Hard exercises before track launch, I won't receive the Difficult trophy even when the track launches. I need to complete at least one Hard exercise after the track launches.

Thanks! I've tested many exercises, but I think we should invite other maintainers. It would be good to get more eyes on it.

There are a few exercises that I think would be good additions to a functional language, like react, list-ops and zipper, and I think there are some topics that could benefit from exercises exploring different approaches. For example, one about randomness that uses IO; or one about data structures whose functions return Option, which is the most idiomatic approach.

However, I don't think there is any obvious "hole", we've covered pretty much all the basics and a few things after that. In my opinion, if no bug is found, we are ready to launch.