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


-- | Filtering and folding over arbitrary MonadPlus instances.
--   
--   Filtering and folding over arbitrary <a>MonadPlus</a> instances. This
--   package generalizes many common stream operations such as
--   <a>filter</a>, <a>catMaybes</a> etc.
@package monadplus
@version 1.2

module Control.Monad.Plus

-- | Monads that also support choice and failure.
class Monad m => MonadPlus (m :: * -> *)
mzero :: MonadPlus m => m a
mplus :: MonadPlus m => m a -> m a -> m a

-- | This generalizes the list-based <a>concat</a> function.
msum :: MonadPlus m => [m a] -> m a

-- | Direct <a>MonadPlus</a> equivalent of <a>filter</a>
--   <tt><a>filter</a></tt> = <tt>(mfilter:: (a -&gt; Bool) -&gt; [a] -&gt;
--   [a]</tt> applicable to any <a>MonadPlus</a>, for example <tt>mfilter
--   odd (Just 1) == Just 1</tt> <tt>mfilter odd (Just 2) == Nothing</tt>
mfilter :: MonadPlus m => (a -> Bool) -> m a -> m a

-- | Generalizes the <tt>remove</tt> function.
mremove :: MonadPlus m => (a -> Bool) -> m a -> m a

-- | Generalizes the <tt>partition</tt> function.
mpartition :: MonadPlus m => (a -> Bool) -> m a -> (m a, m a)

-- | Translate maybe to an arbitrary <a>MonadPlus</a> type. Generalizes the
--   <tt>maybeToList</tt> function.
mfromMaybe :: MonadPlus m => Maybe a -> m a

-- | Pass through <tt>Just</tt> occurrences. Generalizes the
--   <tt>catMaybes</tt> function.
mcatMaybes :: MonadPlus m => m (Maybe a) -> m a

-- | Modify or discard a value. Generalizes the <tt>mapMaybe</tt> function.
mmapMaybe :: MonadPlus m => (a -> Maybe b) -> m a -> m b