exampleConversion.scala

import converter._

import scala.language.implicitConversions

import scala.math.log10

trait Lengthable {
  def length: Int
}

implicit class LengthableString(self: String) extends Lengthable {
  def length = self.size
}

implicit class LengthableInt(self: Int) extends Lengthable {
  def length = (log10(self)).toInt + 1
}

def printLen(ol: Option[Lengthable]) = ol match {
  case None => println(0)
  case Some(l) => println(l.length)
}

printLen(Some(333))

printLen(Some("asdfasdf"))

optionConverter.scala

package converter
Object converter { 
  implicit def optionConverter[A, B](oa: Option[A])(implicit m: A => B): Option[B] = oa match {
     case None => Option.empty[B]
     case Some(a) => Some(m(a))
   }
}