zipper

In part 1 of our tree zipping series, we identified three "problems" with our solution:

While trawling hackerrank in order to procrastinate doing "real" work, I came across this problem in the Functional Programming section. It has you perform various incremental operations on a rose tree, such as inserting and deleting nodes and visiting adjacent nodes in the tree. In the spirit of sticking with Simple Haskell, our first attempt at the problem will use only one benign language extension and two imports.