Basically I have a slew of optionals coming in as JSON, because as we all know even the most strict schema has edge case missing values. When trying to turn Option[A] to string with the standard interpolator it looks like:

None,Some("us"),None,Some(14) 

So here's a better way that uses an interpolator for Option[A] which yields code that looks like:

val city = None 
val country = Some("us") 
val language = None 
val decibels = Some(14)
o"$city,$country,$language,$decibels" 

produces:

,us,,14

And here's the magic, mostly stolen from the Scala StringContext source code:

implicit class OptionStringInterpolator(val sc: StringContext) extends AnyVal { 
 import sc.parts
 def o(args: Any*) = optionInterpolator(StringContext.treatEscapes, args)
 private def optionInterpolator(process: String => String, args: Seq[Any]): String = {
 checkLengths(args)
 val pi = parts.iterator
 val ai = args.iterator
 val builder = new StringBuilder(process(pi.next()))
 while (ai.hasNext) {
 val resolved = ai.next() match {
 case Some(s) => s
 case None => ""
 case o => o
 }
 builder append resolved
 builder append process(pi.next())
 }
 builder.toString()
 }
 def checkLengths(args: Seq[Any]): Unit =
 if (parts.length != args.length + 1)
 throw new IllegalArgumentException("wrong number of arguments ("+ args.length 
 +") for interpolated string with "+ parts.length +" parts")
 }