Add Effect module to docs site.

examples/docs/app/Effect.elm

@@ -0,0 +1,51 @@
+module Effect exposing (Effect(..), batch, fromCmd, map, none, perform)
+
+import Http
+import Json.Decode as Decode
+
+
+type Effect msg
+    = None
+    | Cmd (Cmd msg)
+    | Batch (List (Effect msg))
+
+
+none : Effect msg
+none =
+    None
+
+
+batch : List (Effect msg) -> Effect msg
+batch =
+    Batch
+
+
+fromCmd : Cmd msg -> Effect msg
+fromCmd =
+    Cmd
+
+
+map : (a -> b) -> Effect a -> Effect b
+map fn effect =
+    case effect of
+        None ->
+            None
+
+        Cmd cmd ->
+            Cmd (Cmd.map fn cmd)
+
+        Batch list ->
+            Batch (List.map (map fn) list)
+
+
+perform : (pageMsg -> msg) -> Effect pageMsg -> Cmd msg
+perform fromPageMsg effect =
+    case effect of
+        None ->
+            Cmd.none
+
+        Cmd cmd ->
+            Cmd.map fromPageMsg cmd
+
+        Batch list ->
+            Cmd.batch (List.map (perform fromPageMsg) list)

examples/docs/app/Shared.elm

@@ -3,6 +3,7 @@ module Shared exposing (Data, Model, Msg, template)
 import Browser.Navigation
 import DataSource
 import DocsSection
+import Effect exposing (Effect)
 import Html exposing (Html)
 import Html.Styled
 import Pages.Flags
@@ -60,27 +61,27 @@ init :
             , metadata : route
             , pageUrl : Maybe PageUrl
             }
-    -> ( Model, Cmd Msg )
+    -> ( Model, Effect Msg )
 init navigationKey flags maybePagePath =
     ( { showMobileMenu = False
       , counter = 0
       , navigationKey = navigationKey
       }
-    , Cmd.none
+    , Effect.none
     )
 
 
-update : Msg -> Model -> ( Model, Cmd Msg )
+update : Msg -> Model -> ( Model, Effect Msg )
 update msg model =
     case msg of
         OnPageChange _ ->
-            ( { model | showMobileMenu = False }, Cmd.none )
+            ( { model | showMobileMenu = False }, Effect.none )
 
         ToggleMobileMenu ->
-            ( { model | showMobileMenu = not model.showMobileMenu }, Cmd.none )
+            ( { model | showMobileMenu = not model.showMobileMenu }, Effect.none )
 
         IncrementFromChild ->
-            ( { model | counter = model.counter + 1 }, Cmd.none )
+            ( { model | counter = model.counter + 1 }, Effect.none )
 
 
 subscriptions : Path -> Model -> Sub Msg