Actually you need width, height and radius to be numbers not strings.
Otherwise you'll get parsing errors.
{ "tag": "rectangle", "width": 2, "height": 3}
{ "tag": "circle", "radius": 2}
On Wed, May 18, 2016 at 10:36 PM Mario Sangiorgio <mariosangior...@gmail.com>
wrote:
> No, the json explicitly has a tag attribute to let your code know what is
> the shape type it encodes followed by the attributes for that shape.
>
> Something like:
> { "tag": "rectangle", "width": "2", "height": "3"}
> { "tag": "circle", "radius": "2"}
>
> Note that there is no nesting.
>
> Mario
>
> On Wed, May 18, 2016 at 10:29 PM Eelco Hoekema <ehoek...@gmail.com> wrote:
>
>> Hi,
>>
>> I'm a bit stuck in decoding some json. In
>> http://package.elm-lang.org/packages/elm-lang/core/4.0.0/Json-Decode#andThen
>> there is an example of decoding a tagged union for a shape.
>>
>> type Shape
>> = Rectangle Float Float
>> | Circle Float
>> shape : Decoder Shapeshape =
>> ("tag" := string) `andThen` shapeInfo
>> shapeInfo : String -> Decoder ShapeshapeInfo tag =
>> case tag of
>> "rectangle" ->
>> object2 Rectangle
>> ("width" := float)
>> ("height" := float)
>>
>> "circle" ->
>> object1 Circle
>> ("radius" := float)
>>
>> _ ->
>> fail (tag ++ " is not a recognized tag for shapes")
>>
>>
>> How would the corresponding JSON look like? Should that be
>>
>> {"rectangle" : {"width" : "2", "height": "3"}}
>>
>>
>>
>> eelco
>>
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