scalaz/scalaz — pull request #86 by schmmd (2012-03-31 23:11:37+00:00)
Title: Bug fixes, added test cases, and corrected comments in Zipper class.

I fixed Zipper.start and Zipper.end. Previously both methods were broken. To determine this and write a fix I added a test case for both Zipper.start and Zipper.end. While adding test cases, I also added a test case for Zipper.update.

In making this change, I wanted to use Zipper.move to compare against Zipper.start and Zipper.end. From reading the comment, I inferred that Zipper.move(0) would always move to the start of the zipper. It turns out that Zipper.move(n) changes the location n steps from the present location. This behavior makes sense but didn't agree with the comment, so I rewrote the comment on Zipper.move.