List filter

Question

Given a List , I would like to filter out any elements that are equal to Unit - () .

Is there a better filtering method than through this code?

 scala> List( () ).filter( x => x != () ) <console>:8: warning: comparing values of types Unit and Unit using `!=' will always yield false List( () ).filter( x => x != () ) ^ res10: List[Unit] = List() 

Answer 1

I would go with this:

 List(1, (), 4, (), 9, (), 16) filter (_ != ()) res0: List[AnyVal] = List(1, 4, 9, 16) 

Answer 2

You can use pattern matching:

 list.filter(_ match { case x : Unit => false case x => true}) 

Answer 3

 scala> List(()).filterNot(_.isInstanceOf[Unit]) res0: List[Unit] = List() scala> List((),1,2).filterNot(_.isInstanceOf[Unit]) res1: List[AnyVal] = List(1, 2)