Drop Eq constraint that isn't needed.
Drop the redundant Maybe from findZ return type. Breaks symmetry but
makes it easier to use (join no longer needed).
* Explicitly import pure, (<$>), (<*>) and (<$) from Control.Applicative.
* Use DeriveDataTypeable pragma.
* Remove type signature from pattern synonym.
Utility functions for working with Maybe Stacks, including:
- useful conversions to and from lists
- insertUp/Down, swapUp/Down, focusUp/Down, etc
- maps, filters and folds