Questions tagged [universal-trait]

In the specification of value classes, it says: A value class can only extend universal traits and cannot be extended itself. A universal trait is a trait that extends Any, only has defs as members, and does no initialization. Universal traits…

Sometimes in Scala/Scala.js I see trait Foo extends AnyVal { ... } – what's the meaning and purpose of extends AnyVal here? I'm aware of value classes, and that they can not extend traits that extend AnyRef, so using extends AnyVal would make sense…