On Mon, Aug 19, 2013 at 2:09 PM, Brandon Allbery <allbery.b@gmail.com> wrote:
Alternatively, have you considered using your own ADT? `data Validity = Success | Failure String` would give you more readable / comprehensible code without needing to worry about assumptions or common usage.
Or possibly Valid and Invalid as the constructors....
This also means you can easily extend it later to include multiple errors, or position information, or other annotations. You could also use it with Monoid and/or the Writer monad to track success/failure in the most appropriate way for your project, instead of being constrained to the behavior of an existing instance.