elm-spa/README.md

# elm-spa

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## single page apps made easy

When you create an app with the [elm/browser](https://package.elm-lang.org/packages/elm/browser/latest) package, you can build anything from a static `Html msg` page to a fully-fledged web `Browser.application`.

__elm-spa__ uses that design at the page-level, so you can quickly add new pages to your Elm application!

Make your page as simple as you need:

```elm
module Pages.Home exposing (page)

-- can render a static page
page =
    Spa.static
      { view = view
      }
```

```elm
module Pages.About exposing (page)

-- can keep track of page state
page =
    Spa.sandbox
      { init = init
      , update = update
      , view = view
      }
```

```elm
module Pages.Posts exposing (page)

-- can perform side effects
page =
    Spa.element
      { init = init
      , update = update
      , subscriptions = subscriptions
      , view = view
      }
```

```elm
module Pages.SignIn exposing (page)

-- can read and update global state
page =
    Spa.component
      { init = init
      , update = update
      , subscriptions = subscriptions
      , view = view
      }
```

### putting your pages together is super easy!

```elm
init : Route -> Global.Model -> ( Model, Cmd Msg, Cmd Global.Msg )
init route =
    case route of
        Route.Home -> pages.home.init ()
        Route.About -> pages.about.init ()
        Route.Posts slug -> pages.posts.init slug
        Route.SignIn -> pages.signIn.init ()
```

```elm
update : Msg -> Model -> Global.Model -> ( Model, Cmd Msg, Cmd Global.Msg )
update bigMsg bigModel =
    case ( bigMsg, bigModel ) of
        ( Home_Msg msg, Home_Model model ) ->
            pages.home.update msg model

        ( About_Msg msg, About_Model model ) ->
            pages.about.update msg model
      
        ( Posts_Msg msg, Posts_Model model ) ->
            pages.posts.update msg model
      
        ( SignIn_Msg msg, SignIn_Model model ) ->
            pages.signIn.update msg model

        _ ->
            always ( bigModel, Cmd.none, Cmd.none )
```

```elm
-- handle view and subscriptions in one case expression!
bundle : Model -> Global.Model -> { view : Document Msg, subscriptions : Sub Msg }
bundle bigModel =
    case route of
        Home_Model model -> pages.home.bundle model
        About_Model model -> pages.about.bundle model
        Posts_Model model -> pages.posts.bundle model
        SignIn_Model model -> pages.signIn.bundle model
```

### install the npm package

The [cli tool](https://www.npmjs.com/package/elm-spa) has commands like `elm-spa init`, `elm-spa add`, and `elm-spa build` for
generating your routes and pages for you!

```
npm install -g elm-spa
elm-spa init new-project
```

### install the elm package

If you'd rather define routes and pages by hand,
you can add [the elm package](https://package.elm-lang.org/packages/ryannhg/elm-spa/latest/Spa) to your project:

```
elm install ryannhg/elm-spa
```

### rather see an example?

This repo comes with an example project that you can
play around with. add in some pages and see how it works!

```
git clone https://github.com/ryannhg/elm-spa
cd example
npm start
```