If I have a List[Option[A]] in Scala, what is the idiomatic way to filter out the None values?
One way is to use the following:
val someList: List[Option[String]] = List(Some("Hello"), None, Some("Goodbye"))
someList.filter(_ != None)
Is there a more "idiomatic" way? This does seem pretty simple.
If you want to get rid of the options at the same time, you can use flatten:
scala> someList.flatten
res0: List[String] = List(Hello, Goodbye)
someList.filter(_.isDefined) if you want to keep the result type as List[Option[A]]
The cats library also has flattenOption, which turns any F[Option[A]] into an F[A] (where F[_] is a FunctorFilter)
import cats.implicits._
List(Some(1), Some(2), None).flattenOption == List(1, 2)
