A week ago I finally found a way to split up my messages in different categories (Here is the SO question where I got my answer)
Now I have implemented this solution:
type Msg
= AMsg AMsg
| BMsg BMsg
| CMsg CMsg
and then I defined AMsg as follows
type AMsg
= ActionOne Int String
| ActionTwo Int
Everything works great except when I use ActionOne with a onInput Html.Event
input [onInput (AMsg (ActionOne model.id))] []
This errors out telling me that onInput needs a String -> Msg type but is getting a AMsg type.
This would work just fine if I was using onClick for example and pass in the second argument myself
input [onClick (AMsg (ActionOne model.id "hello"))] []
But since I need to use onInput and that is what passes the second String parameter to ActionOne I am stuck. If I change my types to adapt to this
type Msg
= AMsg AMsg String
| BMsg BMsg
| CMsg CMsg
type AMsg
= ActionOne Int
| ActionTwo Int
This works, but then i force ActionTwo to also take a string, which i don't want.
Otherwise I am stuck specifying ActionOne directly under Msg
type Msg
= AMsg AMsg
| BMsg BMsg
| CMsg CMsg
| ActionOne Int String
type AMsg
= ActionTwo Int
I really care about separating Msgs into different categories -- if I want to use elm for a bigger project this seems pretty crucial to me. Any ideas ?
The function that you pass to onInput has to have the type String -> msg (or more specifically in your case, String -> Msg.)
You can accomplish that by using a lambda:
input [onInput (\str -> (AMsg (ActionOne model.id str)))] []
You can also use function composition (the << function) to achieve the same thing without needing to talk about the parameter str explicitly:
input [ onInput <| AMsg << ActionOne model.id ]