Scala 3 enum is already sealed

By Alvin Alexander. Last updated: January 22, 2021

As a brief note to self, a Scala 3 enum is already sealed, so you never need to write sealed enum.

The Scala 3 docs demonstrate this. They state that an enum is “used to define a type consisting of a set of named values.” Then they share this example:

enum Color:
   case Red, Green, Blue

Finally they state, “This defines a new sealed class, Color, with three values, Color.Red, Color.Green, Color.Blue. The color values are members of Colors companion object.”

So again, a Scala 3 enum is already sealed. (I’m sure this probably shows up as an error in an IDE if you try to use sealed enum, but I’m not using an IDE atm.)

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