[Haskell-beginners] Selecting single result of function application to list

[Markus Läll]

There's also newtype First wraping a Maybe in Data.Monoid, in which
you can wrap your Maybes, mconcat them and get the first Just value.
Like:

> mconcat $ map First [Nothing, Just "first", Nohing, Just "last", Nothing]
First {getFirst = Just "first"}


On Thu, Nov 3, 2011 at 6:07 PM, Hugo Ferreira <hmf at inescporto.pt> wrote:
> Hello,
>
> Apologies the simpleton question but I would like to
> know how it is done in Haskell. I have a list of values,
> and I am applying a function to each of these elements.
> The result is a Maybe. I would like to return the first
> occurrence which is not a Nothing.
>
> I am considering something like:
>
> selectOne f = take 1 . filter (\e -> case e of
>                                       Just _ -> True
>                                       _ -> False ) . map f
>
> I this how it is done?
>
> TIA,
> Hugo F.
>
>
>
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-- 
Markus Läll