Oh I see! Makes totally sense :) Thank you very much!
On Thursday, 28 July 2016 17:32:13 UTC+1, Yosuke Torii wrote: > > Hi Simone, > > I wrote the fixed version here > <https://gist.github.com/jinjor/bf37f10713028a1d9ef547724bcf5532> (copy & > paste to Try Elm <http://elm-lang.org/try>). > Union type was not wrong. The `on` function assumes an event object to be > decoded, but you expect a string. > So I used `targetValue` decoder, which is a shortcut for `e.target.value`. > > > 2016年7月28日木曜日 0時25分46秒 UTC+9 Simone Vittori: >> >> I'm building a language selector and I'd like to map the options to a >> union type. >> >> Here's what I tried: >> >> import Json.Decode exposing (Decoder, customDecoder, string) >> >> {-| Currently supported languages. -} >> type Language >> = English >> | Japanese >> >> >> {-| A JSON decoder of Language. -} >> languageDecoder : Decoder Language >> languageDecoder = >> customDecoder string fromStringLanguage >> >> >> fromStringLanguage : String -> Result String Language >> fromStringLanguage str = >> case str of >> "English" -> Ok English >> "Japanese" -> Ok Japanese >> other -> Err ("Invalid language: " ++ other) >> >> And here's how I'm using it: >> >> -- MODEL >> >> type alias Model = Language >> >> >> -- UPDATE >> >> type Msg >> = Change Language >> >> update : Msg -> Model -> Model >> update msg model = >> case msg of >> Change language -> language >> >> >> -- VIEW >> >> view : Model -> Html Msg >> view model = >> Html.form [] >> [ select [ on "change" <| Json.Decode.map Change languageDecoder ] >> (List.map (viewOption model) ["English", "Japanese"]) >> ] >> >> It does compile successfully, but when I select another option from the >> dropdown list, nothing happens. Any ideas? >> Is this the right way of decoding a union type? >> > -- You received this message because you are subscribed to the Google Groups "Elm Discuss" group. To unsubscribe from this group and stop receiving emails from it, send an email to elm-discuss+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
