use page file to make type errors nicer

example/src/Page.elm

@@ -0,0 +1,81 @@
+module Page exposing
+    ( Page, Document, Bundle
+    , upgrade
+    , static, sandbox, element, component
+    )
+
+{-|
+
+@docs Page, Document, Bundle
+
+@docs upgrade
+
+@docs static, sandbox, element, component
+
+-}
+
+import Browser
+import Global
+import Spa
+
+
+type alias Document msg =
+    Browser.Document msg
+
+
+type alias Page flags model msg =
+    Spa.Page flags model msg Global.Model Global.Msg
+
+
+type alias Bundle msg =
+    Spa.Bundle msg
+
+
+upgrade :
+    (pageModel -> model)
+    -> (pageMsg -> msg)
+    -> Page pageFlags pageModel pageMsg
+    ->
+        { init : pageFlags -> Global.Model -> ( model, Cmd msg, Cmd Global.Msg )
+        , update : pageMsg -> pageModel -> Global.Model -> ( model, Cmd msg, Cmd Global.Msg )
+        , bundle : pageModel -> Global.Model -> Bundle msg
+        }
+upgrade =
+    Spa.upgrade
+
+
+static : { view : Document msg } -> Page flags () msg
+static =
+    Spa.static
+
+
+sandbox :
+    { init : model
+    , update : msg -> model -> model
+    , view : model -> Document msg
+    }
+    -> Page flags model msg
+sandbox =
+    Spa.sandbox
+
+
+element :
+    { init : flags -> ( model, Cmd msg )
+    , update : msg -> model -> ( model, Cmd msg )
+    , subscriptions : model -> Sub msg
+    , view : model -> Document msg
+    }
+    -> Page flags model msg
+element =
+    Spa.element
+
+
+component :
+    { init : Global.Model -> flags -> ( model, Cmd msg, Cmd Global.Msg )
+    , update : Global.Model -> msg -> model -> ( model, Cmd msg, Cmd Global.Msg )
+    , subscriptions : Global.Model -> model -> Sub msg
+    , view : Global.Model -> model -> Document msg
+    }
+    -> Page flags model msg
+component =
+    Spa.component

example/src/Pages/About.elm

@@ -5,21 +5,20 @@ module Pages.About exposing
     , page
     )
 
-import Browser exposing (Document)
 import Data.Tab as Tab exposing (Tab)
 import Html exposing (..)
 import Html.Attributes as Attr exposing (class)
 import Html.Events as Events
-import Spa exposing (Page)
+import Page exposing (Document, Page)
 
 
 
 -- PAGE
 
 
-page : Spa.Page Flags Model Msg globalModel globalMsg
+page : Page Flags Model Msg
 page =
-    Spa.sandbox
+    Page.sandbox
         { init = init
         , update = update
         , view = view

example/src/Pages/Authors/Dynamic/Posts/Dynamic.elm

@@ -5,10 +5,9 @@ module Pages.Authors.Dynamic.Posts.Dynamic exposing
     , page
     )
 
-import Browser exposing (Document)
 import Html exposing (..)
 import Html.Attributes as Attr exposing (class)
-import Spa exposing (Page)
+import Page exposing (Document, Page)
 
 
 type alias Flags =
@@ -27,9 +26,9 @@ type alias Msg =
     Never
 
 
-page : Page Flags Model Msg globalModel globalMsg
+page : Page Flags Model Msg
 page =
-    Spa.element
+    Page.element
         { init =
             \flags ->
                 ( Model flags.param1 flags.param2

example/src/Pages/NotFound.elm

@@ -5,10 +5,9 @@ module Pages.NotFound exposing
     , page
     )
 
-import Browser exposing (Document)
 import Html exposing (..)
 import Html.Attributes as Attr exposing (class)
-import Spa exposing (Page)
+import Page exposing (Document, Page)
 
 
 type alias Flags =
@@ -23,14 +22,14 @@ type alias Msg =
     Never
 
 
-page : Page Flags Model Msg globalModel globalMsg
+page : Page Flags Model Msg
 page =
-    Spa.static
+    Page.static
         { view = view
         }
 
 
-view : Document msg
+view : Document Msg
 view =
     { title = "NotFound"
     , body =

example/src/Pages/Posts/Dynamic.elm

@@ -5,10 +5,9 @@ module Pages.Posts.Dynamic exposing
     , page
     )
 
-import Browser exposing (Document)
 import Html exposing (..)
 import Html.Attributes as Attr exposing (class)
-import Spa exposing (Page)
+import Page exposing (Document, Page)
 
 
 type alias Flags =
@@ -25,9 +24,9 @@ type alias Msg =
     Never
 
 
-page : Page Flags Model Msg globalModel globalMsg
+page : Page Flags Model Msg
 page =
-    Spa.element
+    Page.element
         { init = \flags -> ( Model flags.param1, Cmd.none )
         , update = \_ model -> ( model, Cmd.none )
         , subscriptions = \_ -> Sub.none

example/src/Pages/Posts/Top.elm

@@ -5,10 +5,9 @@ module Pages.Posts.Top exposing
     , page
     )
 
-import Browser exposing (Document)
 import Html exposing (..)
 import Html.Attributes as Attr exposing (class, href)
-import Spa exposing (Page)
+import Page exposing (Document, Page)
 
 
 type alias Flags =
@@ -23,14 +22,14 @@ type alias Msg =
     Never
 
 
-page : Page Flags Model Msg globalModel globalMsg
+page : Page Flags Model Msg
 page =
-    Spa.static
+    Page.static
         { view = view
         }
 
 
-view : Document msg
+view : Document Msg
 view =
     { title = "Posts"
     , body =

example/src/Pages/Profile.elm

@@ -5,23 +5,22 @@ module Pages.Profile exposing
     , page
     )
 
-import Browser exposing (Document)
 import Browser.Navigation as Nav
 import Data.User as User exposing (User)
 import Global
 import Html exposing (..)
 import Html.Attributes exposing (alt, class, src)
 import Html.Events as Events
-import Spa exposing (Page)
+import Page exposing (Document, Page)
 
 
 
 -- PAGE
 
 
-page : Spa.Page Flags Model Msg Global.Model Global.Msg
+page : Page Flags Model Msg
 page =
-    Spa.component
+    Page.component
         { init = always init
         , update = always update
         , subscriptions = always subscriptions

example/src/Pages/Top.elm

@@ -1,9 +1,8 @@
 module Pages.Top exposing (Flags, Model, Msg, page)
 
-import Browser exposing (Document)
 import Html exposing (..)
 import Html.Attributes as Attr exposing (class)
-import Spa exposing (Page)
+import Page exposing (Document, Page)
 
 
 type alias Flags =
@@ -18,14 +17,14 @@ type alias Msg =
     Never
 
 
-page : Page Flags Model Msg globalModel globalMsg
+page : Page Flags Model Msg
 page =
-    Spa.static
+    Page.static
         { view = view
         }
 
 
-view : Document msg
+view : Document Msg
 view =
     { title = "Homepage"
     , body =