Elm intro

button.elm

import Html exposing (Html, button, div, text)
import Html.App as App
import Html.Events exposing (onClick)


main =
  App.beginnerProgram { model = model, view = view, update = update }


-- MODEL

type alias Model = { one: Int, two: Int }

model : Model
model =
  { one = 0, two = 10 }


-- UPDATE

type Msg = Increment | Decrement | Reset

update : Msg -> Model -> Model
update msg model =
  case msg of
    Increment ->
      { model | one = model.one + 1, two = 20 }

    Decrement ->
      { model | one = model.one - 1 }

    Reset ->
      { model | one = 0 }

-- VIEW

view : Model -> Html Msg
view model =
  div []
    [ button [ onClick Decrement ] [ text "-" ]
    , div [] [ text (toString model.one) ]
    , div [] [ text (toString model.two) ]
    , button [ onClick Increment ] [ text "+" ]
    , button [ onClick Reset ] [ text "Reset" ]
    ]