leftToMaybe/rightToMaybe

[Herbert Valerio Riedel]

On 2013-08-06 at 12:21:14 +0200, Christopher Done wrote:
> How about popping these in Data.Either?
>
> -- | Maybe get the left side of an Either.
> leftToMaybe :: Either a b -> Maybe a
> leftToMaybe = either Just (const Nothing)
>
> -- | Maybe get the right side of an Either.
> rightToMaybe :: Either a b -> Maybe b
> rightToMaybe = either (const Nothing) Just

+1


Some minor nitpicking: IMHO, the naming is inconsistent with
respect to the existing functions:

  listToMaybe :: [a] -> Maybe a
  maybeToList :: Maybe a -> [a]

In these two cases, '[lL]ist' and '[mM]aybe' both denote types, whereas
in '{left,right}ToMaybe', 'left' is a constructor and 'Maybe' is a type.
However, I have no better naming alternative to offer.

-- hvr