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nicck/Counter.elm

Created May 17, 2017 10:42
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Counter.elm
module Counter exposing (view, update, Msg)
import Data exposing (Model)
import Html exposing (Html, body, div, button, text)
import Html.Attributes exposing (attribute, class)
-- import Html.Events exposing (onClick)
type Msg
= Increment Int
| Decrement Int
update : Msg -> Model -> Model
update msg model =
case msg of
Increment off ->
{ model | counter = model.counter + off }
Decrement off ->
{ model | counter = model.counter - off }
view : String -> Model -> Html msg
view label model =
div [ class "counter" ]
-- [ button [ onClick (Decrement 2) ] [ text "-" ]
[ button [ ] [ text "-" ]
, div []
[ text (label ++ ": ")
, text (toString model.counter)
]
-- , button [ onClick (Increment 2) ] [ text "+" ]
, button [ ] [ text "+" ]
]
Raw
Data.elm
module Data exposing (Model)
type alias Model =
{ counter : Int
}
Raw
Main.elm
module Main exposing (..)
import Html exposing (Html, body, div, button, text)
import Html.Attributes exposing (attribute, class)
import Counter
import Data exposing (Model)
main : Program Never Model Msg
main =
Html.beginnerProgram { model = model, view = view, update = update }
model : Model
model = { counter = 10 }
type Msg = Counter.Msg | Int
update : Msg -> Model -> Model
update msg model =
case msg of
Counter.Msg ->
Counter.update msg model
view : Model -> Html Msg
view model =
body [ attribute "id" "main" ] [ Counter.view "Counter" model ]
@nicck
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nicck commented May 17, 2017 

-- TYPE MISMATCH ------------------------------------------------------ Main.elm

The 1st argument to function `update` is causing a mismatch.

21|             Counter.update msg model
                               ^^^
Function `update` is expecting the 1st argument to be:

    Counter.Msg

But it is:

    Msg

@1602
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1602 commented May 17, 2017 •
edited
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update : Msg -> Model -> Model
update msg model =
    case msg of
        Counter.Msg counterMsg ->
            Counter.update counterMsg model

@1602
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1602 commented May 17, 2017

sorry, complete fix is:

diff --git a/Main.elm b/Main.elm
index 9b644a7..cc67985 100644
--- a/Main.elm
+++ b/Main.elm
@@ -12,13 +12,15 @@ main =
 model : Model
 model = { counter = 10 }

-type Msg = Counter.Msg | Int
+type Msg = CounterMsg Counter.Msg | In

 update : Msg -> Model -> Model
 update msg model =
     case msg of
-        Counter.Msg ->
-            Counter.update msg model
+        CounterMsg m ->
+            Counter.update m model
+        In ->
+            model


 view : Model -> Html Msg

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