Regarding the outmsg and translating types, you've got 2 options - you can
either keep the outmsg in the scope of the module, or you can pass the
outmsg to the update function from the upper level:
*Outmsg in scope of module*
module MyModule exposing(..)
type Msg
= DoSomething
| DoSomethingElse
type OutMsg
= None
| SomethingHappened String
update : Msg -> Model -> ( Model, OutMsg, Cmd Msg )
update msg model =
case msg of
DoSomething ->
( model, None, Cmd.none )
DoSomethingElse ->
( model, SomethingHappened "I ate a block of cheese" , Cmd.none
)
*outmsg in the scope of parent via config*
module MyModule exposing(..)
type Msg
= DoSomething
| DoSomethingElse
type alias Config msg =
{ onSomethingHappened : String -> msg
, onNoOp : msg
}
update : Config msg -> Msg -> Model -> ( Model, msg , Cmd Msg )
update config msg model =
case msg of
DoSomething ->
( model, config.onNoOp , Cmd.none )
DoSomethingElse ->
( model, config.onSomethingHappened "I ate a block of cheese" ,
Cmd.none )
I'm using Nothing and NoOp in the respective examples - you might want to
use "Maybe" instead, and return Nothing or Just xxx .
How do I trigger a Cmd on the top-level from the update function of a
> module? Must be something to do with Cmd.map...?
Wherever you're managing the returned outmsg in the top level, generate the
Cmd from there.
On Tuesday, September 20, 2016 at 9:30:12 AM UTC-4, Rupert Smith wrote:
>
> On Sunday, September 18, 2016 at 9:33:14 PM UTC+1, Erik Lott wrote:
>>
>> I'm not sure what the outmessage package is that you linked to, but you
>> don't need a package to manage this. An outmsg is just a messge that is
>> returned from the update function, to notify the function caller of
>> something important that happened internally. If you're new to elm, it's
>> probably better to wire an OutMsg yourself, just so you know exactly what's
>> going on with the code. If you haven't yet seen the Sortable Table
>> Example <https://github.com/evancz/elm-sortable-table>, you should have
>> a close look at the code. You'll see great examples of the update and view
>> method returning useful messages.
>>
>
> Yes, I have struggled a bit to figure out how to do that, because I have
> split the code into module, and the return type of the 'update' function in
> a module is different to the return type of the 'update' function in the
> top-level module. How does one translate between those types?
>
> I can see how it is done for a view, using Html.App.map.
>
> How do I trigger a Cmd on the top-level from the update function of a
> module? Must be something to do with Cmd.map...?
>
>
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