MIGRATION.md

Migrating from elm 7.x.x to 8.0.0

If you are upgrading from 7.x.x, you will need to change your code as follows. All necessary changes will be flagged as type errors by the compiler, so you can use the compiler to identify the necessary changes.

1. Most event handlers now live in Options. E.g., there is no longer a Button.onClick; use instead Options.onClick.

   Motivation. This change is to avoid re-implementing substantial parts of Html.Events in each component.

2. Toggles.onClick is renamed Options.onToggle.

   Motivation. This change enables you to register a regular onClick handler should you need to. (onToggle is a shorthand for registering both onClick and onChange.)

3. Textfield now takes an extra argument:

    Textfield.render Mdl [0] model.mdl []           -- 7.x.x
   

   becomes

    Textfield.render Mdl [0] model.mdl [] []        -- 8.0.0
   

   Motivation. Although never used since a Textfield cannot have child elements, this argument makes all elm-mdl render functions have the same number and meaning of parameters.

4. Textfield.inner and Textfield.style become Options.input.

   Motivation. Some elm-mdl components pretend to be input elements, even though they are implemented as a number of divs containing an input element somewhere.

5. Slider.container is renamed Slider.element.

   Motivation. See change (4) above.

6. Options.when x y becomes Options.when y x (switch of parameter order).

   Motivation. when was intended to be used infix, with backticks, but this usage is no longer supported by Elm 0.18. The switching of parameter order allows using when with piping:

    cs "important-css-class" `when` model.isImportant
   

   becomes

    cs "important-css-class" |> when model.isImportant
   

7. The Material.update function now needs a lifting function.

        Material.update msg model                     -- 7.x.x
   
    becomes
   
        Material.update Mdl msg model                 -- 8.0.0
   

   Motivation. This change is necessitated by the move away from the Parts library.