将Option [String]拆分为（Option [String]，Option [String]）

Question

For a normal String I am be able to do like this:

val str = "asdzxc"
val (first, second) = str.splitAt(3) // splits into ("asd", "zxc")

I'd like to be able to do a similar thing for an Option[String] :

val optionalString: Option[String] = getOptionalString(...)
val (firstOption, secondOption) = ???

So that the types of firstOption and secondOption would be Option[String] . I know I can do like this:

optionalString.map(_.splitAt(3))

which returns me an Option[(String, String)] but that is not what I'm looking for. Any ideas?

Answer 1

You can either use a fold:

optionalString.map(_.splitAt(3)).fold((None: Option[String], None: Option[String])) { case (a, b) => (Some(a), Some(b)) }

Or pattern matching (possibly a bit clearer since it doesn't need the explicit type parameters):

optionalString.map(_.splitAt(3)) match {
  case None => (None,None)
  case Some((a,b)) => (Some(a), Some(b))
}