Optional tuples to Map in Scala

Question

If I have a List of tuples, I can convert to a map with toMap:

val x = (3 -> 3)
List(x).toMap

and I get

scala.collection.immutable.Map[Int,Int] = Map(3 -> 3)

If I have a List of Optional and try the same I would get an error:

val x = Some(3 -> 3)
val y = None
List(x, y).toMap

<console>:15: error: Cannot prove that Some[(Int, Int)] <:< (T, U).

I want to get the same result. Is it possible?

I would expect the same result as before, converting x and ignoring y because is a None: scala.collection.immutable.Map[Int,Int] = Map(3 -> 3) — pedrorijo91, Jan 07 '16 at 22:29

score 5 · Accepted Answer · answered Jan 07 '16 at 22:29

5

You can use flatten on the List to remove the Nones:

val x = Some(3 -> 3)
val y = None
List(x, y).flatten.toMap

> scala.collection.immutable.Map[Int,Int] = Map(3 -> 3)

answered Jan 07 '16 at 22:29

Jean Logeart

note that there is an implicit conversion from `Option` to `List` in this case. – Yann Moisan Jan 08 '16 at 08:55

1 Answers1