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


-- | A backtracking logic-programming monad.
--   
--   A continuation-based, backtracking, logic programming monad. An
--   adaptation of the two-continuation implementation found in the paper
--   <a>Backtracking, Interleaving, and Terminating Monad Transformers</a>
--   available here: <a>http://okmij.org/ftp/papers/LogicT.pdf</a>
@package logict
@version 0.2.3


-- | A backtracking, logic programming monad.
--   
--   Adapted from the paper /Backtracking, Interleaving, and Terminating
--   Monad Transformers/, by Oleg Kiselyov, Chung-chieh Shan, Daniel P.
--   Friedman, Amr Sabry
--   (<a>http://www.cs.rutgers.edu/~ccshan/logicprog/LogicT-icfp2005.pdf</a>)
module Control.Monad.Logic.Class

-- | Minimal implementation: msplit
class (MonadPlus m) => MonadLogic m
msplit :: (MonadLogic m) => m a -> m (Maybe (a, m a))
interleave :: (MonadLogic m) => m a -> m a -> m a
(>>-) :: (MonadLogic m) => m a -> (a -> m b) -> m b
ifte :: (MonadLogic m) => m a -> (a -> m b) -> m b -> m b
once :: (MonadLogic m) => m a -> m a

-- | The inverse of msplit. Satisfies the following law:
--   
--   <pre>
--   msplit m &gt;&gt;= reflect == m
--   </pre>
reflect :: (MonadLogic m) => Maybe (a, m a) -> m a
instance (MonadLogic m, Monoid w) => MonadLogic (WriterT w m)
instance (MonadLogic m, Monoid w) => MonadLogic (WriterT w m)
instance (MonadLogic m) => MonadLogic (StateT s m)
instance (MonadLogic m) => MonadLogic (StateT s m)
instance (MonadLogic m) => MonadLogic (ReaderT e m)
instance MonadLogic []


-- | A backtracking, logic programming monad.
--   
--   Adapted from the paper /Backtracking, Interleaving, and Terminating
--   Monad Transformers/, by Oleg Kiselyov, Chung-chieh Shan, Daniel P.
--   Friedman, Amr Sabry
--   (<a>http://www.cs.rutgers.edu/~ccshan/logicprog/LogicT-icfp2005.pdf</a>).
module Control.Monad.Logic

-- | The basic Logic monad, for performing backtracking computations
--   returning values of type <tt>a</tt>
data Logic a

-- | Runs a Logic computation with the specified initial success and
--   failure continuations.
runLogic :: Logic a -> (a -> r -> r) -> r -> r

-- | Extracts the first result from a Logic computation.
observe :: Logic a -> a

-- | Extracts up to a given number of results from a Logic computation.
observeMany :: Int -> Logic a -> [a]

-- | Extracts all results from a Logic computation.
observeAll :: Logic a -> [a]

-- | A monad transformer for performing backtracking computations layered
--   over another monad <tt>m</tt>
data LogicT m a

-- | Runs a LogicT computation with the specified initial success and
--   failure continuations.
runLogicT :: LogicT m a -> (a -> m r -> m r) -> m r -> m r

-- | Extracts the first result from a LogicT computation, failing
--   otherwise.
observeT :: (Monad m) => LogicT m a -> m a

-- | Extracts up to a given number of results from a LogicT computation.
observeManyT :: (Monad m) => Int -> LogicT m a -> m [a]

-- | Extracts all results from a LogicT computation.
observeAllT :: (Monad m) => LogicT m a -> m [a]
instance (MonadState s m) => MonadState s (LogicT m)
instance (MonadReader r m) => MonadReader r (LogicT m)
instance MonadLogic Logic
instance MonadPlus Logic
instance Monad Logic
instance Alternative Logic
instance Applicative Logic
instance Functor Logic
instance Traversable Logic
instance Foldable Logic
instance (Monad m) => MonadLogic (LogicT m)
instance (MonadIO m) => MonadIO (LogicT m)
instance MonadTrans LogicT
instance (Monad m) => MonadPlus (LogicT m)
instance (Monad m) => Monad (LogicT m)
instance (Applicative f) => Alternative (LogicT f)
instance (Applicative f) => Applicative (LogicT f)
instance (Functor f) => Functor (LogicT f)
instance Applicative Identity