Scala Options Explained

Options.scala

/**
  * Option Collections
  *
  * Some developers see Option as a safe replacement for null values,
  * notifying users that the value may be missing and
  * reducing the likelihood that its use will trigger a Null PointerException.
  * Others see it as a safer way to build chains of operations,
  * ensuring that only valid values will persist for the duration of the chain.
  *
  * The Option type is itself unimplemented but relies on two subtypes for the implementation:
  * Some, a type-parameterized collection of one element; and
  * None, an empty collection. The None type has no type parameters because it never contains contents.
  */

var indeed: String = "Indeed"
var optionIndeed = Option(indeed)
indeed = null
optionIndeed = Option(indeed)

def divide(amt: Double, divisor: Double) : Option[Double] =
{
  if(divisor == 0) None
  else Option(amt/divisor)
}
//divide: divide[](val amt: Double,val divisor: Double) => Option[Double]

val legit = divide(5,2)
//legit: Option[Double] = Some(2.5)
val illegal = divide(3,0)
//illegal: Option[Double] = None

val value_legit:Any = legit.getOrElse("You Divided by Zero Yo");
//value_legit: Any = 2.5
val value_illegal:Any = illegal.getOrElse("You Divided by Zero Yo");
//value_illegal: Any = You Divided by Zero Yo

val odds = List(1, 3, 5)
//odds: List[Int] = List(1, 3, 5)
/**
  * headOption, which returns the head element wrapped in an Option,
  * ensuring that it will work even on empty lists.
  */
val firstOdd = odds.headOption
//firstOdd: Option[Int] = Some(1)
val first:Any = firstOdd.getOrElse("BAD")
val evens = odds filter (_ % 2 == 0)
//evens: List[Int] = List()
val firstEven = evens.headOption
//firstEven: Option[Int] = None
val multipleOfFive = odds filter (_ % 5 == 0)
//multipleOfFive: List[Int] = List(5)

val words = List("risible", "scavenger", "GIST", "passenger", "ranger", "ranker")
//Predicate function: Functions that return a boolean.
val uppercase:Option[String] = words find (word => (word == word.toUpperCase))
//uppercase: Option[String] = Some(GIST)

val o:Object = uppercase.getOrElse(new Animal())
//o: Object = GIST
val a:Any = uppercase.getOrElse(5)
//a: Any = GIST
val s:String = uppercase.getOrElse("EMPTY STRING")
//s: String = GIST