-- Hoogle documentation, generated by Haddock
-- See Hoogle, http://www.haskell.org/hoogle/


-- | Generalization of catMaybes
--   
@package witherable
@version 0.0

module Data.Witherable

-- | Like <tt>traverse</tt>, but you can remove elements instead of
--   updating them. <tt>traverse f = wither (fmap Just . f)</tt> Minimal
--   complete definition: <a>wither</a> or <a>catMaybes</a>.
class Traversable t => Witherable t where wither f = fmap catMaybes . traverse f catMaybes = runIdentity . wither pure witherM f = unwrapMonad . wither (WrapMonad . f)
wither :: (Witherable t, Applicative f) => (a -> f (Maybe b)) -> t a -> f (t b)
catMaybes :: (Witherable t, Witherable t) => t (Maybe a) -> t a
witherM :: (Witherable t, Monad m) => (a -> m (Maybe b)) -> t a -> m (t b)

-- | <a>blightM</a> is <a>witherM</a> with its arguments flipped.
blightM :: (Monad m, Witherable t) => t a -> (a -> m (Maybe b)) -> m (t b)
instance Witherable Seq
instance Witherable Vector
instance Witherable (Const r)
instance (Eq k, Hashable k) => Witherable (HashMap k)
instance Ord k => Witherable (Map k)
instance Witherable IntMap
instance Witherable []
instance Witherable Maybe