Created
August 2, 2019 15:32
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Testing Elm concurrency with a kind of extreme example.
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| module Main exposing (main) | |
| import Html exposing (Html, br, div, input, text) | |
| import Html.Attributes exposing (defaultValue, type_, value) | |
| import Html.Events exposing (onInput) | |
| -- Elm 0.18 implementation | |
| -- Example can be found on https://ellie-app.com/sbw95cJgz2a1 | |
| -- MODEL | |
| type alias Model = | |
| { inputValues : List String | |
| } | |
| init : ( Model, Cmd Msg ) | |
| init = | |
| ( { inputValues = List.repeat 5000 "" | |
| } | |
| , Cmd.none | |
| ) | |
| -- UPDATE | |
| type Msg | |
| = NoOp | |
| | CaptureInput Int String | |
| update : Msg -> Model -> ( Model, Cmd Msg ) | |
| update msg model = | |
| case msg of | |
| CaptureInput index val -> | |
| let | |
| _ = | |
| Debug.log "val" <| String.length val | |
| updatedModel = | |
| { model | |
| | inputValues = | |
| List.take index model.inputValues | |
| ++ [ val ] | |
| ++ List.drop (index + 1) model.inputValues | |
| } | |
| in | |
| ( updatedModel | |
| , Cmd.none | |
| ) | |
| NoOp -> | |
| ( model, Cmd.none ) | |
| -- VIEW | |
| textHtml : String -> List (Html Msg) | |
| textHtml val = | |
| [ br [] [] | |
| , text val | |
| ] | |
| inputHtml : Int -> String -> List (Html Msg) | |
| inputHtml index val = | |
| [ br [] [] | |
| , text val | |
| , br [] [] | |
| {- Transform this to an "uncontrolled" component in order | |
| to solve the concurrency problem here. ie remove the | |
| `value` attribute. | |
| -} | |
| , input [ type_ "text", onInput (CaptureInput index), value val ] [] | |
| ] | |
| view : Model -> Html Msg | |
| view model = | |
| div [] | |
| ([ text "Race Condition checking" ] | |
| ++ (List.concat <| List.indexedMap inputHtml model.inputValues) | |
| ++ (List.concat <| List.map textHtml model.inputValues) | |
| ) | |
| -- PROGRAM | |
| main : Program Never Model Msg | |
| main = | |
| Html.program | |
| { view = view | |
| , init = init | |
| , update = update | |
| , subscriptions = always Sub.none | |
| } |
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| module Main exposing (main) | |
| import Browser | |
| import Html exposing (Html, br, div, input, text) | |
| import Html.Attributes exposing (type_, value) | |
| import Html.Events exposing (onInput) | |
| -- Elm 0.19 implementation ( throws a "Maximum CallStack size exceeded" runtime error. Need to take a look ) | |
| -- MODEL | |
| type alias Model = | |
| { inputValues : List String | |
| } | |
| initialModel : ( Model, Cmd Msg ) | |
| initialModel = | |
| ( { inputValues = List.repeat 5000 "" | |
| } | |
| , Cmd.none | |
| ) | |
| -- UPDATE | |
| type Msg | |
| = NoOp | |
| | CaptureInput Int String | |
| update : Msg -> Model -> ( Model, Cmd Msg ) | |
| update msg model = | |
| case msg of | |
| CaptureInput index val -> | |
| let | |
| _ = | |
| Debug.log "val" <| String.length val | |
| updatedModel = | |
| { model | |
| | inputValues = | |
| List.take index model.inputValues | |
| ++ [ val ] | |
| ++ List.drop (index + 1) model.inputValues | |
| } | |
| in | |
| ( updatedModel | |
| , Cmd.none | |
| ) | |
| NoOp -> | |
| ( model | |
| , Cmd.none | |
| ) | |
| -- VIEW | |
| textHtml : String -> List (Html Msg) | |
| textHtml val = | |
| [ br [] [] | |
| , text val | |
| ] | |
| inputHtml : Int -> String -> List (Html Msg) | |
| inputHtml index val = | |
| [ br [] [] | |
| , text val | |
| , br [] [] | |
| {- Transform this to an "uncontrolled" component in order | |
| to solve the concurrency problem here. | |
| -} | |
| , input [ type_ "text", onInput (CaptureInput index), value val ] [] | |
| ] | |
| view : Model -> Html Msg | |
| view model = | |
| div [] | |
| ([ text "Race Condition checking" ] | |
| ++ (List.concat <| List.indexedMap inputHtml model.inputValues) | |
| ++ (List.concat <| List.map textHtml model.inputValues) | |
| ) | |
| -- PROGRAM | |
| main : Program () Model Msg | |
| main = | |
| Browser.element | |
| { init = \_ -> initialModel | |
| , view = view | |
| , update = update | |
| , subscriptions = \_ -> Sub.none | |
| } |
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