toEither.scala

templateService.getById(id) match {
  case Found(template) => ...
  case NotFound(message) => // message contains a nice (consistent message)
}

for {
  checklist <- checklistService.getById(checklistId).toRight("checklist").right
  template <- templateService.getById(checklist.template.id).toRight
} yield {
  ...
}

// It can also have a toOption if needed, although I'm not sure when that would be used

templateService.getById(id).toOption match {
  case Some(tmpl) =>
  case None =>
}

// Alternatively, we could use a helper method like toEither:

for {
  checklist <- checklistService.getById(checklistId).toRight("checklist").right
  template <- toEither(templateService.getById(checklist.template.id)) // converts to Either[String, Template]
} yield {
  ...
}

// I think this might be the best

The only comment I have about it, in the last option, can we do templateService.getById(checklist.template.id).toEither?

toOption could definitely be handy.

Yeah, there's a way to make extension methods like that (it's called the Pimp My Library pattern)

so, what are these: checklist <- checklistService.getById(checklistId).toRight("checklist").right? Example of an old way?