Un-optioning an optioned Option

Question

Say I have a val s: Option[Option[String]]. It can thus have the following values:

Some(Some(\"foo\")) Some(None) None

Answer 1

You could use scalaz join to do this, as this is one of the monadic operations:

doubleOpt.join

Here it is in the REPL:

scala> import scalaz._; import Scalaz._
import scalaz._
import Scalaz._

scala> some(some("X")).join
res0: Option[java.lang.String] = Some(X)

scala> some(none[String]).join
res1: Option[String] = None

scala> none[Option[String]].join
res3: Option[String] = None

It's available to anything with a typeclass instance for a Monad.