In QML, you can effectively derive TypeA by creating a TypeB.qml looking like

TypeA {
    function reimplemented() {
        foo();
    }
}

However there is no way to get to the base TypeA.reimplemented in case you want to call the base type and then just add something more too it.

Arguably QML is following a more JS like prototype based model that doesn't have proper inheritance, but it is often used in this way and it would be nice to be a little more powerful than JS, at least for the QML types.