It's not exactly what you want but you get most of the benefit by just wrapping types in enum variants.

It's a request for the following to be valid

    enum X {
        A,
        B,
    }
    fn foo() -> X::A {
        X::A
    }

which helps a lot when composing state machines. In the meantime, you can indeed do what you propose:

    enum X {
        A(Foo),
        B(Bar),
    }
    struct Foo;
    struct Bar;
    fn foo() -> Foo {
        Foo
    }

Thanks yeah, I was just meaning for the ergonomics aspect :) Cheers

Since I've heard of this idea, I keep finding places where id use it, whether that be for variant-specific behavior or to remove the redudant type definitions in my API.