Yes, that was the goal. That way the UI state is utterly deterministic /
reproducible in isolation of all outside services.
That's a good point on the race conditions. I only use Cmd.batch because
it's the facility that came to mind. (I'm still getting acquainted with
Elm.) I don't know if Cmd.batch makes any ordering guarantee.
If not we'd be more or less back to square one. Abuse `update` to do both
things.
doSideEffects: Act -> Model -> (Maybe Evt, Cmd Evt)
doSideEffects act model =
case act of
UpdateCustomer customer ->
(Just CustomerUpdateRequested, callServerWithCustomer customer)
...
updateModel: Evt -> Model -> Model
... -- implementation as previous
maybeUpdateModel: Maybe Evt -> Model -> Model
maybeUpdateModel evtOpt model =
case evtOpt of
Nothing ->
model
Just evt ->
updateModel evt model
update : Msg -> Model -> (Model, Cmd Msg)
update msg model =
case msg of
Action act ->
let
(eventNow, command) = doSideEffects act model
in
(maybeUpdateModel eventNow model, Cmd.map Evt command)
Event evt ->
(updateModel evt model, Cmd.none)
So this should apply an event immediately if one is needed for the action.
But it still keeps the model updating events separate.
These immediate events would be seen by a userland event-store
implementation (which is underneath updateModel), but I bet the TTD
wouldn't see it since it doesn't come from Elm.
On Thursday, August 11, 2016 at 3:43:36 PM UTC-5, OvermindDL1 wrote:
>
> So you really are wanting to hard device events into two different ones,
> those that can *only* alter the model, and those that can *only* send
> commands (which may call ones that alter the model). Unsure if it might
> actually happen but might have to take into account possible race
> conditions for if other messages appear before your other expected ones are
> processed through? Easier to do that atomically all at once?
>
>
> On Thursday, August 11, 2016 at 2:25:22 PM UTC-6, Kasey Speakman wrote:
>>
>> doSideEffects above would also have to map Cmd Evt to Cmd Msg.
>>
>
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