Scala: Creating Options from Seq/Tuple and add to a Sequence

Question

Edit:

Suppose I have a Seq:

Seq(Some("Earth"),Some("Mars"))

I need to add few more elements at start of this sequence. Values to be added are generated based on an Option value. So I try to do as:

 val o = ....//Option calculated here
 Seq(o.map(myFunction(_)),"Earth","Mars")

 def myFunction(s: String) = s match {
     case "x" => Seq(Some("Jupiter"), Some("Venus"))
     case "y"  => Seq(Some("PLuto"), Some("Mercury"))
 }

But map would give me Some(Seq(.....)).

So supposing the Option was a Some then you want to prepend all the elements returned by myFunction if it was a None then nothing should be added, right? — Luis Miguel Mejía Suárez
– Luis Miguel Mejía Suárez, Commented Jul 8, 2021 at 15:33

Luis Miguel Mejía Suárez · Accepted Answer · 2021-07-08 15:47:28Z

2

For this kind of problem I recommend checking the Scaladoc and following a technique called type-tetris.

You need this:

def prependIfDefined(data: Option[A], previousElements: Seq[Option[B]]): Seq[Option[B]] =
  data.fold(ifEmpty = Seq.empty[Option[B]])(getNewData) ++ previousElements

def getNewData(a: A): Seq[Option[B]] = ???

answered Jul 8, 2021 at 15:47

Luis Miguel Mejía Suárez

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