How to convert/wrap a sequence in scala to an Option[Seq] so that if the list is empty, the Option is None

Question

I could do this with an if an statement, but there is probably a "scala" way to do this.

  def notScalaConv(in: Seq[String]): Option[Seq[String]] = {
    if (in.isEmpty)
      None
    else
      Option(in)
  }

`if` is an expression in Scala, which is uncommon in other language: using it this way looks "scalaish" to me — Bruno Grieder, Feb 24 '17 at 18:43
As you wrote it, your `if` wouldn't work, because the value of a one-branch `if` is always `Unit`. I've corrected it by adding `else`. — Seth Tisue, Feb 24 '17 at 19:13

marstran · Accepted Answer · 2017-02-24T19:03:42.173

18

You can lift your Seq to an Option, and then filter it. Like this:

 def notScalaConv(in: Seq[String]): Option[Seq[String]] = {
     Option(in).filter(_.nonEmpty)
 }

edited Feb 24 '17 at 19:03

answered Feb 24 '17 at 18:37

marstran

Better to use `nonEmpty` than a double negative. – Michael Zajac Feb 24 '17 at 18:58
@MichaelZajac So that is what it's called. I couldn't find it with my quick search. Thanks :) – marstran Feb 24 '17 at 19:04

1 Answers1