Comment by fsdjkflsjfsoij

For a trivial example, let's say I have some message type that has multiple variants with differing fields:

    enum Message {
        Action1(String, Option<Mode>),
        Action2(String),
    }

Action1 and Action2 are variants not types and I cannot make functions that take an Action1 or an Action2 as a parameter. To get around this people will often make each enum variant just a container for some struct with the same name but that's more verbose and matching becomes slightly uglier. Code like this is fairly common:

    struct Action1(String, Option<Mode>);

    struct Action2(String);

    enum Message {
        Action1(Action1),
        Action2(Action2),
    }

Ideally I'd like to be able to succinctly say something like:

    type A = B | C

and have A be dependent on B and C but have both B and C be completely independent types.