Use Structural Typing to safely close any resource while using it in a transparent manner.

Closables.scala

object ImAClosable {
  def work() = {
    println("working...")
  }
  
  def close() {
    prinlnt("closing...")
  }
}

object ImNotClosable {
  def work() = {
    println("just wait...")    
  }
}

Main1.scala

object Main1 {
  def main(args: Array[String]) {
    ResourceHandler.managed(ImAClosable) { // prints working... and then closing...
      work()
    }
  }
}

Main2.scala

object Main2 {
  def main(args: Array[String]) {
    ResourceHandler.managed(ImNotClosable) { // <- doesn't compile!
      work()
    }
  }
}

ResourceHandler.scala

object ResourceHandler {
  def managed[X <: {def close(): Unit}, Y](resource: X)(f: X => Y) = {
    Option(resource) match {
       case None => throw new NullPointerException("Can't close a null resource")
       case Some(value) => 
          implicit val implicitResource = value
          try {
            f(implicitResource)
          }
          finally {
            implicitResource.close()
          }
    }
  }
}