Extensible Enums

[Kaylen Wheeler]

I understand that Enums can be fairly easily emulated by unions of value types. However, is there a way to extend or inherit from such a type?

[Ambrose Bonnaire-Sergeant]

You can inherit from the type by including it in another union. Extending a type is something I haven't considered in detail, did you have a use-case in mind?

[Kaylen Wheeler]

It's related to the use case I described in another post about having a map from a type tag to an object of that type.  If I use something like symbols or keywords to represent type tags, then I'd like to be able to define something like:

(defalias ComponentTag (U ...))

But then have the flexibility to introduce new component tags later on.

If I used the inheritance with unions method, could I introduce new symbols that could still typecheck as valid ComponentTags?

[Kaylen Wheeler]

Also, could you maybe provide an example of the inheritance you're talking about?