Add saddle-points exercise

[ageron]

No description provided.

[ageron]

My solution is really verbose. Sometimes I don't really know how to solve a simple problem without a full page of code in Roc, with a lot of error handling. I mean here's the equivalent code in Python, it took me about 2 minutes to write. I'm not quite there yet in Roc:

matrix = [[1,5,3],[1,4,3],[1, 2, 2]]
result = [{"row": y + 1, "column": x + 1} for (y, row) in enumerate(matrix) for (x, val) in enumerate(row)
if val == max(row) and val == min((0 if len(r) < x else r[x]) for r in matrix)]

[Anton-4]

Thanks for bringing this up @ageron, I've created roc-lang/roc#7118 for this.

[isaacvando]

Unfortunately I don't have any immediate suggestions for making the code more terse. I will say that these kind of 2d array problems always seem very annoying in functional languages. Otherwise, looks good!