Custom CellCodec for Option

[philippeehlert]

Hi! I'm trying to create a CellCodec that encodes/decodes Option[E] values in a way that:

1. Option[E].empty values are encoded to - instead of an empty cell
2. - values are decoded as Option[E].empty

Going through the source code, I imagined that it would be possible to do something using the already existent optionEncoder and optionDecoder, but I couldn't figure out how exactly to do it. Can you guys tell me if it is possible and give me any advice on how to do it?

Thanks!

[nrinaudo]

I'm so very sorry - I had answered this the day you posted it, but apparently I had no coverage and never realised my answer never actually got posted. I hope you managed to work it out on your own. Otherwise, I fear I might have lost a user, but here's a possible solution just in case somebody else needs it:

scala> implicit def opt[E: CellEncoder]: CellEncoder[Option[E]] = CellEncoder.from {
     |   case Some(e) => CellEncoder[E].encode(e)
     |   case None => "-"
     | }
opt: [E](implicit evidence$1: kantan.csv.CellEncoder[E])kantan.csv.CellEncoder[Option[E]]

scala> CellEncoder[Option[Int]].encode(Some(2))
res1: String = 2

scala> CellEncoder[Option[Int]].encode(None)
res2: String = -