I've put up a module https://github.com/nordlow/justd/blob/master/enums.d

that provides two type constructors

- EnumChain
- EnumUnion

that can be used to combine names or names-and-values from one or more enums.

I would now like to define rules for assignments and implicit conversions with the following checks

- Assignment to EnumUnion, EnumChain from its parts is always nothrow.
- Assignment from EnumUnion, EnumChain to its parts may throw.

to emulate Ada's subtype.

Is it currently possible to implement any of these?

Also do you think the namings EnumChain and EnumUnion are correct?

> I would now like to define rules for assignments and implicit conversions with the following checks

I believe I found a good solution through struct wrappers. See update at:

https://github.com/nordlow/justd/blob/master/enums.d