Yes, I'm doing basically the same (define constant a as literal type, then use "typeof" operator to define action type, and then create alias for all Actions using union type).

That's one of the reasons why I miss possibility to tell what is the type of the object that function returns. So I could do something like this (hypothetical syntax)

    const INCREMENT: "increment" = "increment";
    const DECREMENT: "decrement" = "decrement";

    function increment(inc: number) {
        return {
            type: INCREMENT,
            inc
        };
    }

    function decrement(dec: number) {
        return {
            type: DECREMENT,
            dec
        };
    }

    type Actions =
        returntypeof increment
        | returntypeof decrement;

So I won't need to write action type when I have action creator method. I hope that in future Typescript devs will add some feature to allow this kind of pattern.