Functor Abstraction Pattern

Scratch.scala

import cats.Functor

trait ImplicitInstances {
  implicit val OptionInstance: Functor[Option] = new Functor[Option] {
    override def map[A, B](fa: Option[A])(f: (A) => B): Option[B] = fa.map(f)
  }
}

final class FuncAbs[M[_]] {
  def double(s: M[String])(implicit functor : Functor[M]) = functor.map(s)(str => str + str)
}

object Main extends App with ImplicitInstances {
  val opt = new FuncAbs[Option]
  val dub = opt.double(Some("foo"))
  println(dub)
}