Views

With elm-spa, you can choose any Elm view library you like. Whether it's elm/html, Elm UI, or even your own custom library, the View module has you covered!

Ejecting the default view

If you would like to switch to another UI library– you can move the View.elm file from .elm-spa/defaults into your src folder:

.elm-spa/
 |- defaults/
     |- View.elm

-- move into

src/
 |- View.elm

From here on out, elm-spa will use your View module as the return type for all view functions across your pages!

View msg

By default, a View lets you set the tab title as well as render some Html in the body value.

type alias View msg =
    { title : String
    , body : List (Html msg)
    }

Using Elm UI

If you wanted to use Elm UI, a popular HTML/CSS alternative in the community, you would tweak this View msg type to not use Html msg:

import Element exposing (Element)

type alias View msg =
    { title : String
    , element : Element msg
    }

View.toBrowserDocument

Whichever library you use, Elm needs a way to convert it to a Browser.Document type. Make sure to provide this function, so elm-spa can convert your UI at the top level.

Here's an example for Elm UI:

toBrowserDocument : View msg -> Browser.Document msg
toBrowserDocument view =
    { title = view.title
    , body =
        [ Element.layout [] view.element
        ]
    }

View.map

When connecting pages together, elm-spa needs a way to map from one View msg to another. For elm/html, this is the Html.map function.

But when using a different library, you'll need to specify the map function for things to work.

Fortunately, most UI libraries ship with their own! Here's another example with Elm UI:

map : (a -> b) -> View a -> View b
map fn view =
    { title = view.title
    , element = Element.map fn view.element
    }

View.none

When loading between pages, elm-spa also needs a View.none to be specified for your custom View type.

For Elm UI, that is just Element.none:

none : View msg
none =
    { title = ""
    , element = Element.none
    }

View.placeholder

The last thing you need to provide is a View.placeholder, used by the elm-spa add command to provide a stubbed out view function implementation.

Here's an example of a placeholder with Elm UI:

placeholder : String -> View msg
placeholder pageName =
    { title = pageName
    , element = Element.text pageName
    }

Next up: Examples

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