Code used in my blog post: Introduction to Option Type - https://last-ent.com/posts/introduction-to-option-type/

intro-to-options.scala

/*
  BASIC EXAMPLE
*/
val hMap0: Map[Int, Int] = Map(1 -> 102, 2 -> 202, 3 -> 302)

hMap0.get(100) 
// What should be the value here?
// `100` does not exist in `hMap`

/*
  EXTRACTOR FROM OPTION
*/
def getFromOption(opt: Option[String]): String =
    "Got Value: " + opt.getOrElse("None")

getFromOption(Some("100")) // "Got Value: 100"
getFromOption(None) // "Got Value: None" 

def extractFromOption(opt: Option[String]): String =
  opt match {
    case None        => "Got Value: " + "None"
    case Some(value) => "Got Value: " + value
  }

extractFromOption(Some("100")) // "Got Value: 100"
extractFromOption(None) // "Got Value: None" 

/*
  FUNCTIONS FOR WORKING WITHIN CONTEXT
*/
val hMap: Map[Int, Value] = 
  Map(
    1 -> Value(102),
    2 -> Value(202),
    3 -> Value(302)
  )

def getOptionValue(i: Int): Option[Value] = hMap.get(i)

def addTen(i: Value): Value10 = Value10(i.value + 10)

def asString(num: Value10): String =
  s"Got Value: ${num.value}"

case class Value(value: Int)
case class Value10(value: Int)

/*
  WORKING WITHIN CONTEXT
*/
def mapOpt(i: Int): Option[String] =
  getOptionValue(i)
    .map(addTen)
    .map(asString)

extractFromOption(mapOpt(3)) // "Got Value: 312"
extractFromOption(mapOpt(100)) // "Got Value: None"

def forOpt(i: Int): Option[String] =
  for {
    value <- hMap.get(i)
    val10 <- Option.apply(addTen(value))
    str   <- Option.apply(asString(val10))
  } yield str

extractFromOption(forOpt(3)) // "Got Value: 312"
extractFromOption(forOpt(100)) // "Got Value: None"

def flatMapOpt(i: Int): Option[String] =
  getOptionValue(i)
    .flatMap(valOpt => Option.apply(addTen(valOpt)))
    .flatMap(val10 => Option.apply(asString(val10)))

extractFromOption(flatMapOpt(3)) // "Got Value: 312"
extractFromOption(flatMapOpt(100)) // "Got Value: None"