Functor Typeclass

The functor is one of the most well-known typeclasses. It's on top of the hierarchy for the applicative and the monad, since both extend from it. Learn:

• Inheritance relation between Functor, Applicative and Monad.
• How the Functor provides mapping behavior and how's that probably needed on any app.
• Examples of mapping with functor instances of some known data types like Option<A> or Either<L, R>.
• Why we say some data types are biased and how that affects to combinators like map.
• How to provide or write your own Functor instances.
• How to use map to stack computations over data.