nullsafe.scala

object NullSafeConversions {
  implicit def ns[A](a:A) = new NullSafe(a)
  implicit def ro[A](o:Option[A]) = new RichOption(o)
  
  def ?[A](a:A) = if (a == null) Some(a) else None
  
  case class NullSafe[A](a:A) extends AnyVal {
    def ?[B >: Null](f: A => B):B = if (a != null) f(a) else null
  }
  case class RichOption[A](o:Option[A]) extends AnyVal { 
    def ?[B](f: A => B):Option[B] = { o.map(f) }
  }
}

object Test extends App {
  import NullSafeConversions._
  import scala.collection.immutable._ 
  
  case class X(y:Y, z:Z)
  case class Y(x:X, z:Z)
  case class Z(x:X, y:Y)  
  
  val x:X = X(null,null)
  val z:Z 
      = try { x.y.z } catch { case _:Throwable => null }
  val nz:Z 
      = x?(_.y)?(_.z)
  val oz:Option[Z] 
      = ?(x)?(_.y)?(_.z)  
  
  val list1:List[List[List[String]]] 
      = List(List(List("1")))
  val l1:String 
      = list1(0)(0)(0)
  val ol1:String 
      = list1?(_(0))?(_(0))?(_(0))
  val nl1:Option[String] 
      = ?(list1)?(_(0))?(_(0))?(_(0))
  
  val list2:List[List[Int]] 
      = List(List(1))
  val l2:Int 
      = list2(0)(0)
  val nl2:Any 
      = list2?(_(0))?(_(0)) // expected
  val ol2:Option[Int] 
      = ?(list2)?(_(0))?(_(0))
}