How do I get the value of `Either` inside `when`? ...

# arrow

[aeruhxi]

How do I get the value of Either inside when?

when (newPost) {
            is Either.Left -> return@post call.respond(HttpStatusCode.NotFound, mapOf("message" to "One of ids supplied does not exist."))
            is Either.Right -> call.respond(HttpStatusCode.Created, mapOf("post" to /*insert here*/))
        }