Scala witness for serializable data

SerializableSafe.scala

/** Witness that a type is safe to serialize. */
@implicitNotFound(msg="Could not show ${S} to be serialization-safe")
trait SerializationSafe[S]

/** Serialization-safe witnesses. */
object SerializationSafe {

  /** If you are serializable, you are serialization-safe. */
  implicit def serializableIsSafe[S <: Serializable](s: S) = new SerializationSafe[S] {}

  /** If you are a primitive, you are serialization-safe. */
  implicit def valuesAreSafe[A <: AnyVal] = new SerializationSafe[A] {}

}

...

// a function that can only be invoked on something that is serialization-safe
def [T : SerializationSafe] somethingThatRequiresSerializableData(t: T) = ...