Re: [Haskell-cafe] Why Either = Left | Right instead of something like Result = Success | Failure

Daniel Fischer writes:

But if you want to have

instance Monad (Either ConcreteType) where ...

, you can have

fail msg = Left someDefaultValue

(or let the value depend on the message) and you can construct Left someMeaningfulValue in concrete situations.

Which happens to make it identical to Maybe ;-) -- Ivan Lazar Miljenovic Ivan.Miljenovic@gmail.com IvanMiljenovic.wordpress.com