Great tip, thanks!
On Tuesday, July 25, 2017 at 12:50:20 AM UTC-7, Christian Charukiewicz
wrote:
>
> In your expensive function example, you should be able to take advantage
> of Html.Lazy to prevent the view from re-running the expensive function
> unless its parameters change. By storing the derived data in the model
> rather than letting Elm handling the caching through the Lazy functions,
> you are effectively doing something similar but at the cost of adding a lot
> of complexity to your application.
>
> On Tuesday, July 25, 2017 at 2:11:22 AM UTC-5, Peter Damoc wrote:
>>
>> Keep derived data in the model if it makes sense to keep derived data in
>> the model.
>>
>> If you have an expensive function that runs and computes a derived value
>> and you would have to call frequently this function in your view, then by
>> all means, computer the derived value in update and save it in the model.
>>
>> If you don't run into a performance problem like the above, keep your
>> model clean and just extract the computation in a function. for example,
>> you could have something like
>>
>> bmiText : Model -> Html msg
>> bmiText {weight, height} =
>> weight / height ^ 2 |> toString |> text
>>
>> this way, everywhere you need that textual representation, you can use
>> it.
>>
>>
>>
>>
>> On Tue, Jul 25, 2017 at 4:23 AM, Ray Toal <ray....@gmail.com> wrote:
>>
>>> This might be an opinion-based question so I can't ask it on
>>> StackOverflow. :-)
>>>
>>> I have a trivial beginnerProgram using the Elm Architecture. It has two
>>> text fields (HTML input elements), one for weight and one for height. The
>>> onInput attributes of each generate a message. The update function accepts
>>> the message and produces the new model.
>>>
>>> The question is: Should the model (a) consist of the width and height
>>> only, or (b) also include the computed BMI (width / height^2)? If the
>>> former, I compute the BMI in the view function; if the latter, I would
>>> compute it in the update function.
>>>
>>> Does anyone have a lot of experience with Elm applications that would
>>> lead them to believe that keeping models as small as possible and computing
>>> derived data in the view function is better than making rich models? I
>>> don't have enough experience with Elm to know. I sense that for a problem
>>> as simple as mine it really doesn't matter (and I in fact got it working
>>> both ways), but as I start scaling up my apps it would be nice to know if
>>> there is best practice here (or not).
>>>
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>>
>>
>>
>> --
>> There is NO FATE, we are the creators.
>> blog: http://damoc.ro/
>>
>
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