When you need to map over an implicit in the current scope

MapImplicit.scala

case class MapImplicit[A](f: A => A)(implicit current: A) {
  def in[B](code: A => B) = code(f(current))
}

// start with an implicit value
implicit val foo: Int = 3

// prints “3”
println(implicitly[Int])

// create a new scope with the mapped implicit
// note that the name of the new implicit should be exactly the same
// (it works by shadowing the old implicit)
MapImplicit[Int](_ + 1).in { implicit foo =>

  // prints “4”
  println(implicitly[Int])

}