Simple form example in Elm

Form.elm

import Html exposing (Html, beginnerProgram, div, button, input, li, text, ul)
import Html.Attributes exposing (value)
import Html.Events exposing (onClick, onInput)
import List exposing (map)


type alias Model =
    { value : String
    , posts : List String
    }


model : Model
model =
    Model "" []


view : Model -> Html Msg
view model =
    div []
        [ div []
            [ input [ value model.value, onInput ChangeValue ] []
            , button [ onClick Send ] [ text "Send" ]
            ]
        , ul [] (map (\post -> li [] [ text post ]) model.posts)
        ]


type Msg
    = ChangeValue String
    | Send


update : Msg -> Model -> Model
update msg model =
    case msg of
        ChangeValue value ->
            { model | value = value }

        Send ->
            Model "" (model.posts ++ [ model.value ])


main : Program Never Model Msg
main =
    beginnerProgram
        { model = model
        , view = view
        , update = update
        }