FunctorUsage

A Functor is a ubiquitous typeclass involving type constructors of kind * → *, which is another way of saying types that have a single type variable. Examples might be Option, List, Future.

The Functor category involves a single operation, named map:

def map[A, B](fa: F[A])(f: A => B): F[B]

This method takes a Function from A => B and turns an F[A] into an F[B]