onStart / onProgress only good for Debug.log ?

[tko]

• onStart and onProgress allow you to monitor progress. This is useful if you want to show a progress bar when uploading a large amount of data.

  , onStart : Maybe (Task () ())
  , onProgress : Maybe (Maybe { loaded : Int, total : Int } -> Task () ())

How can one update the model with the 'loaded' and 'total' values here? I don't see how the callbacks could be used for anything other than Debug.log and succeed () and can't find any examples to the contrary. Shouldn't the signature be Task () (Cmd msg) or am I just not understanding how to trigger an update from these callbacks?

[rtfeldman]

As far as I can make out, think this API made sense in 0.16, but is no longer useful in 0.17.

[evancz]

It should become useful again once processes can communicate, as described here.