implicits mainly, these are objects looked up by the compiler for various purposes e.g. Typeclasses, or how to serialize a specific object to JSON. The Scala 2

implicits mainly, these are objects looked up by the compiler for various purposes e.g. Typeclasses, or how to serialize a specific object to JSON. The Scala 2.8-2.12 collection library was impossible to call from Java, one of the reasons for an upcoming redesign in 2.13.