Talk:Zipper monad

Here's where I'd like to go with this:

TODO

• Generalise! I'm making good progress on writing a more general lib to cover any traversable data structure.
• Better error reporting.
• Name changes:
  • Change it to the 'Traversal monad' (as you shouldn't have to use the zipper for location).
  • Change left and right to move from a right branch to its corresponding left one and vice versa: this fits in better with the BTree lib.