Update from Elm 0.18's Navigation.program to Elm 0.19's Browser.application

* adapt to the new Browser.application API in the following ways:

  * mirror the two-phase handling of URL changes in
    Browser.application's 'onUrlRequest' and 'onUrlChange' by
    bifurcating the RouterMsg variant of WrappedMsg into
    RouterMsgOnUrlChange and RouterMsgOnUrlRequestInternal variants.

  * add a slot to RouterModel to store the new Browser.Navigation.Key,
    and in the update function, use it to invoke
    Browser.Navigation.pushUrl in response to a urlRequestInternal.

  * create a new 'onExternalUrlRequest' function for the user to
    implement, since RouteUrl can handle internal requests for the
    user, but can't do anything sensible with external requests (as
    suggested by @basti1302).

  * eliminate the distinction between App and AppWithFlags, and all
    related duplication, as there is no variant of the new
    Browser.application that doesn't support flags.

* make UrlChange more strongly typed, mirroring the structure of the
  Url.Url record type from elm/url, and rework the way UrlChanges are
  converted to Cmds with a new 'apply : Url -> UrlChange -> Url'
  function.

* update all examples to work with the new API and 0.19 generally

  * include work-arounds for a couple of elm/url bugs
    (elm/url#37 and
    elm/url#17)

  * store the base path in ExampleViewer.Model to illustrate absolute
    path requirement of UrlChange

  * build the examples with '--debug' so users can get an idea for how
    they work under the hood

* update README

  * remove references to complementary packages that aren't compatible
    with 0.19 (which is all of them)

* remove the RouteUrl.Builder module and the use of the sporto/erl
  package, as this functionality is now largely provided by elm/url.

* remove the older RouteHash module, as it was only present to ease
  the transition from elm-route-hash to elm-route-url.  also remove
  example code illustrating its use.

Author: jerith666

README.md

@@ -1,7 +1,7 @@
 # elm-route-url
 
 This is a module for routing single-page-apps in Elm, building on the
-[`elm-lang/navigation`](http://package.elm-lang.org/packages/elm-lang/navigation/latest)
+[`elm/browser`](https://package.elm-lang.org/packages/elm/browser/latest)
 package.
 
 ## Rationale
@@ -18,30 +18,18 @@ So, there are two things going on here:
 * Mapping changes in the browser's location to changes in our app's state.
 
 Now, you can already arrange for these things to happen using
-[`elm-lang/navigation`](http://package.elm-lang.org/packages/elm-lang/navigation/latest).
-Furthermore, there are already a wealth of complementary packages,
-such as:
-
-* [evancz/url-parser](http://package.elm-lang.org/packages/evancz/url-parser/latest)
-* [Bogdanp/elm-combine](http://package.elm-lang.org/packages/Bogdanp/elm-combine/latest)
-* [Bogdanp/elm-route](http://package.elm-lang.org/packages/Bogdanp/elm-route/latest)
-* [etaque/elm-route-parser](http://package.elm-lang.org/packages/etaque/elm-route-parser/latest)
-* [poyang/elm-router](http://package.elm-lang.org/packages/poying/elm-router/latest)
-* [pzingg/elm-navigation-extra](http://package.elm-lang.org/packages/pzingg/elm-navigation-extra/latest)
-* [sporto/erl](http://package.elm-lang.org/packages/sporto/erl/latest)
-* [sporto/hop](http://package.elm-lang.org/packages/sporto/hop/latest)
-
+[`elm/browser`](http://package.elm-lang.org/packages/elm/browser/latest).
 So, what does elm-route-url do differently than the others? First, I'll
 address this practically, then philosophically.
 
 
 ### Mapping changes in the app state to a possible location change
 
-If you were using [`elm-lang/navigation`](http://package.elm-lang.org/packages/elm-lang/navigation/latest)
+If you were using [`elm/browser`](https://package.elm-lang.org/packages/elm/browser/latest)
 directly, then you would make changes to the URL with ordinary commands.
 So, as you write your `update` function, you would possibly return a command,
-using [`modifyUrl`](http://package.elm-lang.org/packages/elm-lang/navigation/1.0.0/Navigation#modifyUrl)
-or [`newUrl`](http://package.elm-lang.org/packages/elm-lang/navigation/1.0.0/Navigation#newUrl).
+using [`replaceUrl`](https://package.elm-lang.org/packages/elm/browser/latest/Browser-Navigation#replaceUrl)
+or [`pushUrl`](https://package.elm-lang.org/packages/elm/browser/latest/Browser-Navigation#pushUrl).
 
 Now, you can make this work, of course. However, the `update` function isn't
 really the perfect place to do this. Your update function looks like this:
@@ -89,11 +77,13 @@ use elm-route-url, you don't have to.
 
 ### Mapping location changes to messages our app can respond to
 
-If you use the official [navigation](http://package.elm-lang.org/packages/elm-lang/navigation/latest)
-package in Elm 0.18 directly, you react to location changes by providing
-an argument to `Navigation.program` which converts a `Location` to a message
-your app can deal with. Those messages are then fed into your `update` function
-as the `Location` changes.
+If you use the official [browser](https://package.elm-lang.org/packages/elm/browser/latest/)
+package in Elm 0.19 directly, you react to location changes by providing
+two arguments to `Browser.application`: `onUrlRequest`, which converts a
+`UrlRequest` to a message your app can use to decide whether to permit the
+requested URL change; and `onUrlChange`, which converts a new `Url` to a
+message your app can deal with. Those messages are then fed into your
+`update` function as the `Url` changes.
 
 On the surface, elm-route-url works in a similar manner, except that it
 asks you to implement a function which returns a list of messages.
@@ -108,8 +98,8 @@ location2messages : Location -> List Message
 `location2messages` will also be called when your `init` function is invoked,
 so you will also get access to the very first `Location`.
 
-So, that is similar to how `Navigation` works. The difference is that
-`Navigation` will send you a message even when you programmatically change
+So, that is similar to how `Browser` works. The difference is that
+`Browser` will send you a message even when you programmatically change
 the URL. By contrast, elm-route-url only sends you messsages for **external**
 changes to the URL -- for instance, the user clicking on a link, opening
 a bookmark, or typing in the address bar. You won't get a message when you've
@@ -133,40 +123,21 @@ by Amitai Burstein, under the heading
 
 ## API
 
-For the detailed API, see the documentation for `RouteUrl` and `RouteHash`
-(there are links to the right, if you're looking at the Elm package site).
-
-The `RouteUrl` module is now the "primary" module. It gives you access to the
-whole `Location` object, and allows you to use the path, query and/or hash, as
-you wish.
+For the detailed API, see the documentation for `RouteUrl` (there's a link to
+the right, if you're looking at the Elm package site).
 
 The main thing that elm-route-url handles is making sure that your
 `location2messages` and `delta2url` functions are called at the appropriate
-moment. How you parse the `Location` (and construct a `UrlChange`) is pretty
-much up to you. Now, I have included a `RouteUrl.Builder` module that could
-help with those tasks. However, you don't need to use it -- many other
-approaches would be possible, and there are links to helpful packages above.
-For my own part, I've been using [evancz/url-parser](http://package.elm-lang.org/packages/evancz/url-parser/latest)
-recently to implement `location2messages`.
-
-The `RouteHash` module attempts to match the old API of elm-route-hash as
-closely as possible. You should be able to re-use your old `delta2update` and
-`location2action` functions without any changes. What will need to change is
-the code in your `main` module that initializes your app. The `RouteHash`
-module will probably be removed in a future version of elm-route-url, so you
-should migrate to using `RouteUrl` at an appropriate moment.
+moment. How you parse the `Url` (and construct a `UrlChange`) is pretty
+much up to you. You can use [`elm/url`](https://package.elm-lang.org/packages/elm/url/latest/)
+to help with those tasks.
 
 
 ## Examples
 
 I've included [example code](https://github.com/rgrempel/elm-route-hash/tree/master/examples/elm-architecture-tutorial)
-which turns the old Elm Architecture Tutorial (upgraded to Elm 0.18) into
-a single-page app. I've included three variations:
-
-* Using the new `RouteUrl` API with the full path.
-* Using the new `RouteUrl` API with the hash only.
-* Using the old `RouteHash` API.
+which turns the old Elm Architecture Tutorial (upgraded to Elm 0.19) into
+a single-page app. I've included two variations:
 
-Note that the example code makes heavy use of the `RouteUrl.Builder` module.
-However, as noted above, you don't necessarily need to use that -- a variety
-of alternative approaches are possible.
+* Using the `RouteUrl` API with the full path.
+* Using the `RouteUrl` API with the hash only.

elm-package.json

@@ -0,0 +1,21 @@
+{
+    "type": "package",
+    "name": "rgrempel/elm-route-url",
+    "summary": "Router for single-page-apps in Elm",
+    "license": "MIT",
+    "version": "5.0.0",
+    "exposed-modules": [
+        "RouteUrl"
+    ],
+    "elm-version": "0.19.0 <= v < 0.20.0",
+    "dependencies": {
+        "ccapndave/elm-update-extra": "4.0.0 <= v < 5.0.0",
+        "elm/browser": "1.0.0 <= v < 2.0.0",
+        "elm/core": "1.0.0 <= v < 2.0.0",
+        "elm/html": "1.0.0 <= v < 2.0.0",
+        "elm/http": "1.0.0 <= v < 2.0.0",
+        "elm/regex": "1.0.0 <= v < 2.0.0",
+        "elm/url": "1.0.0 <= v < 2.0.0"
+    },
+    "test-dependencies": {}
+}

elm.json

@@ -3,9 +3,10 @@ module Example1.Counter exposing (..)
 import Html exposing (..)
 import Html.Attributes exposing (style)
 import Html.Events exposing (onClick)
-import RouteHash exposing (HashUpdate)
-import RouteUrl.Builder exposing (Builder, builder, path, replacePath)
+import RouteUrl exposing (HistoryEntry(..), UrlChange(..))
 import String exposing (toInt)
+import Url exposing (Url)
+
 
 
 -- MODEL
@@ -56,20 +57,19 @@ view : Model -> Html Action
 view model =
     div []
         [ button [ onClick Decrement ] [ text "-" ]
-        , div [ countStyle ] [ text (toString model) ]
+        , div countStyle [ text (String.fromInt model) ]
         , button [ onClick Increment ] [ text "+" ]
         ]
 
 
-countStyle : Attribute any
+countStyle : List (Attribute any)
 countStyle =
-    style
-        [ ( "font-size", "20px" )
-        , ( "font-family", "monospace" )
-        , ( "display", "inline-block" )
-        , ( "width", "50px" )
-        , ( "text-align", "center" )
-        ]
+    [ style "font-size" "20px"
+    , style "font-family" "monospace"
+    , style "display" "inline-block"
+    , style "width" "50px"
+    , style "text-align" "center"
+    ]
 
 
 {-| We add a separate function to get a title, which the ExampleViewer uses to
@@ -83,61 +83,32 @@ title =
 
 
 
--- Routing (Old API)
+-- Routing (New API)
 
 
-{-| For delta2update, we provide our state as the value for the URL.
--}
-delta2update : Model -> Model -> Maybe HashUpdate
-delta2update previous current =
-    Just <|
-        RouteHash.set [ toString current ]
-
+delta2builder : Model -> Model -> Maybe UrlChange
+delta2builder previous current =
+    Just <| NewPath NewEntry <| { path = String.fromInt current, query = Nothing, fragment = Nothing }
 
-{-| For location2action, we generate an action that will restore our state.
--}
-location2action : List String -> List Action
-location2action list =
-    case list of
-        first :: rest ->
-            case toInt first of
-                Ok value ->
-                    [ Set value ]
-
-                Err _ ->
-                    -- If it wasn't an integer, then no action ... we could
-                    -- show an error instead, of course.
-                    []
 
-        _ ->
-            -- If nothing provided for this part of the URL, return empty list
+builder2messages : (Url -> Maybe String) -> Url -> List Action
+builder2messages extractPath url =
+    case extractPath url of
+        Nothing ->
             []
 
+        Just path ->
+            case String.split "/" path of
+                first :: rest ->
+                    case toInt first of
+                        Just value ->
+                            [ Set value ]
 
+                        Nothing ->
+                            -- If it wasn't an integer, then no action ... we could
+                            -- show an error instead, of course.
+                            []
 
--- Routing (New API)
-
-
-delta2builder : Model -> Model -> Maybe Builder
-delta2builder previous current =
-    builder
-        |> replacePath [ toString current ]
-        |> Just
-
-
-builder2messages : Builder -> List Action
-builder2messages builder =
-    case path builder of
-        first :: rest ->
-            case toInt first of
-                Ok value ->
-                    [ Set value ]
-
-                Err _ ->
-                    -- If it wasn't an integer, then no action ... we could
-                    -- show an error instead, of course.
+                _ ->
+                    -- If nothing provided for this part of the URL, return empty list
                     []
-
-        _ ->
-            -- If nothing provided for this part of the URL, return empty list
-            []