elm

I have some record types structured essentially like this: type Body x = { x | pos: (Int,Int) } type Bubble = Body { radius: Int } type Box = Body { width: Int, height: Int } Now I would like to have a mixed list of any of these and perform some operation on the Body part, but still special case handling Box and Bubble other times. For example, having (implementations elided): mv: (Int,Int) -> Body a -> Body a bubble: Bubble box: Box I would like to map (mv (1,1)) [box,bubble] but this fails because Elm deems the types in the list incompatible. Now I could wrap the Box es and Bubble s in an

I just started programming in Elm and am stuck at something: I would like to have a method that can update fields of elements in a list at a certain index. My signature would look like this: updateElement : List (ID, Task) -> Int -> List (ID, Task) with: type alias Task = { description : String, focus : Bool} In this case I would like to set the boolean (focus) of the task at the index given to true and all the others tasks in the list to false. I already tried with arrays in Elm but then I have to work with Maybe and don't think that is a good solution. I suppose I will have to work with 'map

My JSON looks like the following { "resp": [ [1, "things"] , [2, "more things"] , [3, "even more things"] ] } the problem is that I can't parse the JSON tuples into Elm tuples: decodeThings : Decoder (List (Int, String)) decodeThings = field "resp" <| list <| map2 (,) int string It compiles, but when ran, it throws BadPayload "Expecting an Int at _.resp[2] but instead got [3, \"even more things\"] For some reason it reads [3, "even more things"] as only one thing and not as tuple in JSON format. How can I parse my JSON into a List (Int, String) ? Chad Gilbert You need a decoder which turns a

Here's my decoder: decodeData : Json.Decoder (Id, String) decodeData = Json.at ["data", "0"] <| Json.object2 (,) ("id" := Json.int) ("label" := Json.string) The id should logically be Int however my backend sends it as String (e.g. we get "1" instead of 1 ). How can I cast the decoded value to Int ? ... and to answer myself :) I found the solution in this Flickr example decodeData : Json.Decoder (Id, String) decodeData = let number = Json.oneOf [ Json.int, Json.customDecoder Json.string String.toInt ] in Json.at ["data", "0"] <| Json.object2 (,) ("id" := number) ("label" := Json.string) In Elm

I am trying to create a higher order function to create functions to capture only a specific key code. The code is inspired on Evan's "onEnter" function from his todomvc implementation which captures only the enter function. onKeyCode : Int -> Msg -> Attribute Msg onKeyCode keycode msg = let captureKey code = if code == keycode then msg else NoOp in on "keydown" (Json.map captureKey keyCode) onEnter = onKeyCode 13 onEsc = onKeyCode 27 And now I want to add that to an input component in the viewer: input [ class "edit" , id ("todo-" ++ toString item.uid) , value item.message , onInput

I'm trying to modify a simple app from the elm-lang tutorial to first update the model, then trigger another update. update msg model = case msg of MorePlease -> (model, getRandomGif model.topic) NewGif (Ok newUrl) -> ( { model | gifUrl = newUrl }, Cmd.none) NewGif (Err _) -> (model, Cmd.none) -- my addition NewTopic newTopic -> ({ model | topic = newTopic}, MorePlease) This fails in the compiler because the NewTopic branch: The 3rd branch has this type: ( { gifUrl : String, topic : String }, Cmd Msg ) But the 4th is: ( { gifUrl : String, topic : String }, Msg ) So my Msg needs to be type Cmd