[Haskell-cafe] lens and Maybe value

[David Feuer]

Please clarify your question. Your code doesn't compile, and I can't tell
what it's supposed to do.

On Tue, Dec 20, 2022, 11:13 AM PICCA Frederic-Emmanuel <
frederic-emmanuel.picca at synchrotron-soleil.fr> wrote:

> Hello,
>
> I have a data whcih contain a Maybe value
>
> data A = A (_a = Maybe a)
>
> I would like to use a lens in order to merge two values with this log
>
> replace the value only if it is a (Just a)
>
> So My question is
>
> is there something more elegant than
>
> let myA' = case ma of
>               Nothing  -> conf
>               (Just na) -> (a .~ na) myA
>
> Thanks for your help
>
> Frederic
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