This is a very simple type: It's much like Maybe, except instead of Nothing, we have Failure String. A comparison could also be made to Either String. I made this library because I was dissatisfied with the Monad instance for Either. In this type, fail = Failure. It's rather simple. Changes This release does not actually break the API, however I was rather tired when I chose the version number. This should be 0.1.6.