[Haskell-beginners] Beginners Digest, Vol 110, Issue 20

[Andrey Klaus]

sorry, these 2 should be correct

f ma = fmap (\(Proxy a) -> a) ma

f = fmap (\(Proxy a) -> a)

2017-08-25 15:58 GMT+03:00 Andrey Klaus <deepmindster at gmail.com>:

> Hello
>
> f ma = fmap ((Proxy a) -> Just a) ma
>
> or even shorter
>
> f = fmap ((Proxy a) -> Just a)
>
>
> 2017-08-25 15:00 GMT+03:00 <beginners-request at haskell.org>:
>
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>> Today's Topics:
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>>    1.  Maybe a -> Maybe b (PICCA Frederic-Emmanuel)
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>> ----------------------------------------------------------------------
>>
>> Message: 1
>> Date: Fri, 25 Aug 2017 08:05:34 +0000
>> From: PICCA Frederic-Emmanuel
>>         <frederic-emmanuel.picca at synchrotron-soleil.fr>
>> To: "beginners at haskell.org" <beginners at haskell.org>
>> Subject: [Haskell-beginners] Maybe a -> Maybe b
>> Message-ID:
>>         <A2A20EC3B8560D408356CAC2FC148E53BB41B8D4 at SUN-DAG3.synchrotr
>> on-soleil.fr>
>>
>> Content-Type: text/plain; charset="us-ascii"
>>
>> Hello, I have this
>>
>> data Proxy = Proxy String
>>
>> And I want to write a function
>>
>> f :: Maybe Proxy -> Maybe String
>> f ma = case ma of
>>            (Just (Proxy a)) -> Just a
>>            Nothing -> Nothing
>>
>> I was wondering if there is no simpler way to do this ?
>>
>> thanks
>>
>> Frederic
>>
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>> ------------------------------
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>> End of Beginners Digest, Vol 110, Issue 20
>> ******************************************
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