Occasionally I'd like to do something like "execute on the main queue, but as .immediate if that would run on the main queue". This is fairly esoteric, but I want it for scenarios like

return makeSomePromise()
    .fork({ $0.then(on: .mainImmediate, { (value) in
        self.recordValue(value)
    })})

The rationale here is if my client then attaches an .immediate listener and that ends up running on the main thread, I need my own work to have been completed first. In the then case I can work around this by using .immediate and dispatching to the main queue myself if I'm not on the main thread, but that won't work for the map case.

I'm not sold on the .mainImmediate name.