Scala implicit scope requires double import

I can't see why in the following code the import (import b._) that pulls in the implicit def must appear in both position 1 and position 2 for it to work.

package a {
  abstract class Base {}
}

package b {
  import a._

  class Derived(i: Int) extends Base {}

  object b {
    implicit def 开发者_如何学Ci2d(i: Int): Derived = new Derived(i)
  }
}

import a._
// position 1
import b._

object test extends App {
  // position 2  
  import b._

  def doIt(base: Base) {
    println("works")
  }

  doIt(1)
}

At position 1 you are importing everything from the package b and at position 2 you are importing everything from the object b, which includes the implicit def. You could just import b.b._ at position 2.