Glossary of Functional Programming Terms
A type constructor
F[_] together with an operation
forall A, B. (A => B) => F[A] => F[B] that satisfies FunctorLaw,
i.e. that a series of maps may be freely rewritten as a single map on a composed function, and that the identity function, lifted, is a no-op.
A good example from scalaz
def map[A, B](fa: F[A])(f: (A) ⇒ B): F[B]