It still supports most of the old time-travel functionality; the only thing gone is the ability to resume execution from a historical state. I do not think this is a technical limitation, but rather a decision made to simplify the debugging workflow. (Also, import/export is a super valuable feature for QA.)
On Saturday, November 25, 2017 at 12:34:49 PM UTC-5, John Bugner wrote: > > In Elm 0.17, signals were removed, and subscriptions were added. Evan says > here ( http://elm-lang.org/blog/farewell-to-frp ): > >That is all nice, but the big benefit is that Elm is now significantly > easier to learn and use. > I agree! Thinking about my program in terms of MVU (model, view, update) > is easier than trying to put together a signal graph. I'm told that this > change broke things like back-in-time debugging, but I don't know why. Why > is it not possible anymore? It seems that subscriptions grew out of this > successful experiment ( > https://github.com/evancz/start-app/blob/master/src/StartApp.elm ) to > find a way to simplify programming with signals. > > Let's compare the signatures of the 'Program' types ('Config' in > StartApp.elm): > > from https://github.com/evancz/start-app/blob/master/src/StartApp.elm : > >type alias Config model action = > > { init : (model, Effects action) > > , update : action -> model -> (model, Effects action) > > , view : Signal.Address action -> model -> Html > > , inputs : List (Signal.Signal action) > > } > from http://package.elm-lang.org/packages/elm-lang/html/2.0.0/Html : > >type alias : > > { init : (model, Cmd msg) > > , update : msg -> model -> (model, Cmd msg) > > , subscriptions : model -> Sub msg > > , view : model -> Html msg } > > } > > -> Program Never model msg > > They look pretty similar! 'init' is the same. 'update' is the same. But > 'view' and 'subscriptions'/'inputs' are different. 'view' lost a parameter, > and 'subscriptions' gained a parameter. The magic difference that lost us > BiT debugging must be in there, right? I recall reading that BiT debugging > was only possible when the signal graph was static. Wouldn't this > correspond to 'subscriptions' gaining a parameter? (and thus becoming > dynamic?) and about 'view', why did it have/need a 'Signal.Address action' > parameter? > > I guess my question is: wouldn't it have been possible to make Elm use the > MVU model, but still allow BiT debugging? (Basically keep using the > StartApp package?) If so, why then was FRP abandoned? > > -- You received this message because you are subscribed to the Google Groups "Elm Discuss" group. To unsubscribe from this group and stop receiving emails from it, send an email to elm-discuss+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
