How would you avoid the Option.get?

gistfile1.scala

case class Dog(name: String, tailLength: Option[Int])

val dogs = Seq(Dog("Sparky", Some(85)), Dog("Rotty", None))
val (dogsWithTails, dogsWithoutTails) = dogs.partition(_.tailLength.isDefined)

if (! dogsWithoutTails.isEmpty)
  println("These dogs are missing tails: " +
    dogsWithoutTails.map(_.name).mkString(", "))

dogsWithTails.map(dog => {
  val tailLength = dog.tailLength.get // We know it exists because of the partition above
  // ⋮
})


// More realistic version:

case class Dog(name: String, tailLength: Option[Int], weight: Int)

val dogs = Seq(Dog("Sparky", Some(85), 10), Dog("Rotty", None, 15))
val (dogsWithTails, dogsWithoutTails) = dogs.partition(_.tailLength.isDefined)

if (! dogsWithoutTails.isEmpty)
  println("These dogs are missing tails: " +
    dogsWithoutTails.map(_.name).mkString(", "))

dogsWithTails.map(dog => {
  val tailLength = dog.tailLength.get // We know it exists because of the partition above
  someWorkWithSideEffects(tailLength, dog.weight)
})

def someWorkWithSideEffects(tailLength: Int, weight: Int) {
    // ⋮
}

dogsWithTails.flatMap(_.tailLength)

scala> dogs
res16: List[Dog] = List(Dog(Sparky,Some(85)), Dog(Rotty,None))

scala> dogs.map(dog => dog.tailLength.cata(t => t, "missing tail:" + dog.name))
res17: List[Any] = List(85, missing tail:Rotty)

scala> res17.partition(s => s match {
| case i: Int => true
| case _ => false
| })
res21: (List[Any], List[Any]) = (List(85),List(missing tail:Rotty))

For-comprehension:

for {
dog <- dogsWithTails
length <- dog.tailLength
} println(length)

Even though we "know" all of the dogsWithTails have tails I still might:

dogsWithTails.map(dog => {
dog.tailLength.map(tailLength => {
someWorkWithSideEffects(tailLength, dog.weight)
}
})

// another approach where we use partition

scala> val dogs = List(Dog("Sparky", Some(85)), Dog("Rotty", None), Dog("Fuzzy", Some(20)), Dog("Murky", None))
dogs: List[Dog] = List(Dog(Sparky,Some(85)), Dog(Rotty,None), Dog(Fuzzy,Some(20)), Dog(Murky,None))

scala> val (wt, nt) = dogs.partition(_.tailLength.isDefined)
wt: List[Dog] = List(Dog(Sparky,Some(85)), Dog(Fuzzy,Some(20)))
nt: List[Dog] = List(Dog(Rotty,None), Dog(Murky,None))

scala> wt.map(_.tailLength).sequence
res25: Option[List[Int]] = Some(List(85, 20))

scala> nt.map(_.name)
res26: List[String] = List(Rotty, Murky)

scala> nt.map(_.name).mkString(", ")
res27: String = Rotty, Murky

even though we know that tailLength exists for dogsWithTails I might do this:

dogsWithTails.map(dog => {
dog.tailLength.map(tailLength => {
someWorkWithSideEffects(tailLength, dog.weight)
})
})

Even though we know that all dogsWithTails have a tailLength I still might do:

dogsWithTails.map(dog => {
  dog.tailLength.map(tailLength => {
    someWorkWithSideEffects(tailLength, dog.weight)
  })
})

Even though we know that all dogsWithTails have a tailLength I still might do:

dogsWithTails.map(dog => {
  dog.tailLength.map(tailLength => {
    someWorkWithSideEffects(tailLength, dog.weight)
  })
})

Even though we know that all dogsWithTails have a tailLength I still might do:

dogsWithTails.map(dog => {
  dog.tailLength.map(tailLength => {
    someWorkWithSideEffects(tailLength, dog.weight)
  })
})