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1. tryJust_ :: (SomeException -> Maybe b) -> IO a -> IO (Either b a)

   extra	Extra

   Like catch_ but for tryJust

2. untilJustM :: Monad m => m (Maybe a) -> m a

   extra	Extra

   Keep running an operation until it becomes a Just, then return the value inside the Just as the result of the overall loop.

3. whenJust :: Applicative m => Maybe a -> (a -> m ()) -> m ()

   extra	Extra

   Perform some operation on Just, given the field inside the Just. This is a specialized for_.

   whenJust Nothing  print == pure ()
   whenJust (Just 1) print == print 1
   

4. whenJustM :: Monad m => m (Maybe a) -> (a -> m ()) -> m ()

   extra	Extra

   Like whenJust, but where the test can be monadic.

5. whileJustM :: (Monad m, Monoid a) => m (Maybe a) -> m a

   extra	Extra

   Keep running an operation until it becomes a Nothing, accumulating the monoid results inside the Justs as the result of the overall loop.

6. breakJust :: (a -> Maybe b) -> [a] -> ([a], Maybe (b, [a]))

   utility-ht	Data.List.HT

   forAllMaybeFn $ \f xs -> snd (breakJust f xs) == dropWhileNothing f xs
   

7. segmentAfterJust :: (a -> Maybe b) -> [a] -> ([([a], b)], [a])

   utility-ht	Data.List.HT

   >>> segmentAfterJust (\c -> toMaybe (isLetter c) (toUpper c)) "123a5345b---"
   ([("123",'A'),("5345",'B')],"---")
   

8. segmentBeforeJust :: (a -> Maybe b) -> [a] -> ([a], [(b, [a])])

   utility-ht	Data.List.HT

   >>> segmentBeforeJust (\c -> toMaybe (isLetter c) (toUpper c)) "123a5345b---"
   ("123",[('A',"5345"),('B',"---")])
   

9. spanJust :: (a -> Maybe b) -> [a] -> ([b], [a])

   utility-ht	Data.List.HT

   No documentation available.

10. takeWhileJust :: [Maybe a] -> [a]

    utility-ht	Data.List.HT

    This is the cousin of takeWhile analogously to catMaybes being the cousin of filter.

    >>> takeWhileJust [Just 'a', Just 'b', Nothing, Just 'c']
    "ab"
    

    Example: Keep the heads of sublists until an empty list occurs.

    >>> takeWhileJust $ map (fmap fst . viewL) ["abc","def","","xyz"]
    "ad"
    

    For consistency with takeWhile, partitionMaybe and dropWhileNothing it should have been:

    takeWhileJust_ :: (a -> Maybe b) -> a -> [b]
    

    However, both variants are interchangeable:

    takeWhileJust_ f == takeWhileJust . map f
    takeWhileJust == takeWhileJust_ id
    

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