Tag instances with arbitrary types.
Tag instances with arbitrary types. The tags are usually empty traits. Tags have no runtime overhead and are only
used at compile-time for additional type safety.
val berry = new Berry()
val blackBerry: Berry @@ Black = berry.taggedWith[Black]
val blueBerry: Berry @@ Blue = berry.taggedWith[Blue]
// compile error: val anotherBlackBerry: Berry @@ Black = blueBerry
Original idea by Miles Sabin, see: https://gist.github.com/milessabin/89c9b47a91017973a35f