Re: your initial post... you could rewrite the code as
case Maybe.map .cell c of
Just (Letter s) ->
s
_ ->
""
Don't know if that's any easier to read, though.
Regarding null_square: If you want to make sure that null_square is passed
by reference, you can define it as a top-level value. (That said, the
record is so small, I doubt it would make a noticeable performance
difference, unless you're planning on making a gazillion of them.)
On Sat, Sep 24, 2016 at 1:44 PM, Martin DeMello <[email protected]>
wrote:
> Don't think that will work because c is of type Maybe Square, not Maybe
> Cell.
>
> One further question - if I define
>
> let null_square = { cell = Empty, num = 0 }
>
> let get_square maybe_square =
> case maybe_cell of
> Nothing: null_square
> Just s : s
>
> let get_letter maybe_square =
> case maybe_square of
> { Letter s } -> s
> _ -> ""
>
> would that be introducing an inefficient creation of a null_square every
> time I call get_letter or is it just a cheap reference?
>
> martin
>
> On Fri, Sep 23, 2016 at 12:04 PM, Simon <[email protected]> wrote:
>
>> This should work
>>
>> case c of
>> Just (Letter s) ->
>> s
>> _ -> ""
>>
>>
>>
>> On Friday, 23 September 2016 03:50:19 UTC+2, Martin DeMello wrote:
>>>
>>> If I have the following code:
>>>
>>> type Cell = Empty | Letter String
>>>
>>> type alias Square =
>>> { cell : Cell
>>> , num : Int
>>> }
>>>
>>> and c : Maybe Square,
>>>
>>> can I do the following in a single match?
>>>
>>> case c of
>>> Just { cell } ->
>>> case cell of
>>> Letter s -> s
>>> _ -> ""
>>> _ -> ""
>>>
>>> that is, i conceptually want
>>>
>>> case c of
>>> Just { cell = Letter s } -> s
>>> _ -> ""
>>>
>>> martin
>>>
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