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|
module Main exposing (..)
import Html exposing (Html, text, div, span)
import Json.Decode exposing (..)
import Http
-- API interface to Gemma
type alias Task =
{ name : String
, description : Maybe String
, remaining : Int
}
emptyStringFilter s =
if s == "" then
Nothing
else
Just s
decodeEmptyString : Decoder (Maybe String)
decodeEmptyString =
map emptyStringFilter string
decodeTask : Decoder Task
decodeTask =
map3 Task
(field "name" string)
(field "description" decodeEmptyString)
(field "remaining" int)
loadTasks : Cmd Msg
loadTasks =
let
request =
Http.get "http://localhost:4242/tasks" (list decodeTask)
in
Http.send NewTasks request
-- Elm architecture implementation
type Msg
= None
| LoadTasks
| NewTasks (Result Http.Error (List Task))
type alias Model =
{ tasks : List Task
, error : Maybe String
}
renderTask : Task -> Html Msg
renderTask task =
div [] [ span [] [ text task.name ] ]
view : Model -> Html Msg
view model =
div [] (List.map renderTask model.tasks)
update : Msg -> Model -> ( Model, Cmd Msg )
update msg model =
case msg of
LoadTasks ->
( model, loadTasks )
NewTasks (Ok tasks) ->
( { tasks = tasks, error = Nothing }, Cmd.none )
NewTasks (Err err) ->
( { model | error = Just (toString err) }, Cmd.none )
_ ->
( model, Cmd.none )
init : ( Model, Cmd Msg )
init =
( { tasks = [], error = Nothing }, loadTasks )
main : Program Never Model Msg
main =
Html.program
{ init = init
, view = view
, update = update
, subscriptions = always Sub.none
}
|
