On Tuesday, February 14, 2017 at 2:48:26 PM UTC, Rupert Smith wrote:
>
> On Tuesday, February 14, 2017 at 2:28:50 PM UTC, Rupert Smith wrote:
>>
>> Is there some way to avoid this, perhaps using extensible records?
>>
>
> I was kind of hoping something like this might work, but it doesn't:
>
> type alias Positioned a =
> { a | rect : Rectangle }
>
> type alias WithContent a =
> { a | content : Maybe String }
>
> type State
> = Hidden {}
> | Aware (Positioned {})
> | Active (Positioned (WithContent {}))
> | Inactive (Positioned (WithContent {}))
>
Being able to pattern match like this is convenient:
Aware { rect } ->
Unfortunately there doesn't seem to be a way of doing deeper pattern
matching:
SomeState { someMaybe as Just value }
Using the 'as' syntax. Some of the time this will mean using a nested case
statement - although should mostly be avoided as only putting values you
really need in each state should eliminate the Maybes. I have now turned
the 'content' field into a String and dropped its Maybe.
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