Copyright	(c) Andy Gill 2001 (c) Oregon Graduate Institute of Science and Technology 2001
License	BSD-style (see the file LICENSE)
Maintainer	R.Paterson@city.ac.uk
Stability	experimental
Portability	portable
Safe Haskell	Safe
Language	Haskell98

Control.Monad.Trans.List

Contents

The ListT monad transformer
Lifting other operations

Description

Deprecated: This transformer is invalid on most monads

The ListT monad transformer, adding backtracking to a given monad, which must be commutative.

Synopsis

newtype ListT m a = ListT {
- runListT :: m [a]
}
mapListT :: (m [a] -> n [b]) -> ListT m a -> ListT n b
liftCallCC :: CallCC m [a] [b] -> CallCC ( ListT m) a b
liftCatch :: Catch e m [a] -> Catch e ( ListT m) a

The ListT monad transformer

newtype ListT m a Source #

Parameterizable list monad, with an inner monad.

Note: this does not yield a monad unless the argument monad is commutative.

Constructors

ListT
Fields runListT :: m [a]

Instances

Instances details

MonadTrans ListT Source #
Instance details Defined in Control.Monad.Trans.List Methods lift :: Monad m => m a -> ListT m a Source #
Monad m => Monad ( ListT m) Source #
Instance details Defined in Control.Monad.Trans.List Methods (>>=) :: ListT m a -> (a -> ListT m b) -> ListT m b Source # (>>) :: ListT m a -> ListT m b -> ListT m b Source # return :: a -> ListT m a Source #
Functor m => Functor ( ListT m) Source #
Instance details Defined in Control.Monad.Trans.List Methods fmap :: (a -> b) -> ListT m a -> ListT m b Source # (<$) :: a -> ListT m b -> ListT m a Source #
MonadFix m => MonadFix ( ListT m) Source #
Instance details Defined in Control.Monad.Trans.List Methods mfix :: (a -> ListT m a) -> ListT m a Source #
Monad m => MonadFail ( ListT m) Source #
Instance details Defined in Control.Monad.Trans.List Methods fail :: String -> ListT m a Source #
Applicative m => Applicative ( ListT m) Source #
Instance details Defined in Control.Monad.Trans.List Methods pure :: a -> ListT m a Source # (<>) :: ListT m (a -> b) -> ListT m a -> ListT m b Source # liftA2 :: (a -> b -> c) -> ListT m a -> ListT m b -> ListT m c Source # (>) :: ListT m a -> ListT m b -> ListT m b Source # (<*) :: ListT m a -> ListT m b -> ListT m a Source #
Foldable f => Foldable ( ListT f) Source #
Instance details Defined in Control.Monad.Trans.List Methods fold :: Monoid m => ListT f m -> m Source # foldMap :: Monoid m => (a -> m) -> ListT f a -> m Source # foldMap' :: Monoid m => (a -> m) -> ListT f a -> m Source # foldr :: (a -> b -> b) -> b -> ListT f a -> b Source # foldr' :: (a -> b -> b) -> b -> ListT f a -> b Source # foldl :: (b -> a -> b) -> b -> ListT f a -> b Source # foldl' :: (b -> a -> b) -> b -> ListT f a -> b Source # foldr1 :: (a -> a -> a) -> ListT f a -> a Source # foldl1 :: (a -> a -> a) -> ListT f a -> a Source # toList :: ListT f a -> [a] Source # null :: ListT f a -> Bool Source # length :: ListT f a -> Int Source # elem :: Eq a => a -> ListT f a -> Bool Source # maximum :: Ord a => ListT f a -> a Source # minimum :: Ord a => ListT f a -> a Source # sum :: Num a => ListT f a -> a Source # product :: Num a => ListT f a -> a Source #
Traversable f => Traversable ( ListT f) Source #
Instance details Defined in Control.Monad.Trans.List Methods traverse :: Applicative f0 => (a -> f0 b) -> ListT f a -> f0 ( ListT f b) Source # sequenceA :: Applicative f0 => ListT f (f0 a) -> f0 ( ListT f a) Source # mapM :: Monad m => (a -> m b) -> ListT f a -> m ( ListT f b) Source # sequence :: Monad m => ListT f (m a) -> m ( ListT f a) Source #
Contravariant m => Contravariant ( ListT m) Source #
Instance details Defined in Control.Monad.Trans.List Methods contramap :: (a -> b) -> ListT m b -> ListT m a Source # (>$) :: b -> ListT m b -> ListT m a Source #
Eq1 m => Eq1 ( ListT m) Source #
Instance details Defined in Control.Monad.Trans.List Methods liftEq :: (a -> b -> Bool ) -> ListT m a -> ListT m b -> Bool Source #
Ord1 m => Ord1 ( ListT m) Source #
Instance details Defined in Control.Monad.Trans.List Methods liftCompare :: (a -> b -> Ordering ) -> ListT m a -> ListT m b -> Ordering Source #
Read1 m => Read1 ( ListT m) Source #
Instance details Defined in Control.Monad.Trans.List Methods liftReadsPrec :: ( Int -> ReadS a) -> ReadS [a] -> Int -> ReadS ( ListT m a) Source # liftReadList :: ( Int -> ReadS a) -> ReadS [a] -> ReadS [ ListT m a] Source # liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec ( ListT m a) Source # liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [ ListT m a] Source #
Show1 m => Show1 ( ListT m) Source #
Instance details Defined in Control.Monad.Trans.List Methods liftShowsPrec :: ( Int -> a -> ShowS ) -> ([a] -> ShowS ) -> Int -> ListT m a -> ShowS Source # liftShowList :: ( Int -> a -> ShowS ) -> ([a] -> ShowS ) -> [ ListT m a] -> ShowS Source #
MonadZip m => MonadZip ( ListT m) Source #
Instance details Defined in Control.Monad.Trans.List Methods mzip :: ListT m a -> ListT m b -> ListT m (a, b) Source # mzipWith :: (a -> b -> c) -> ListT m a -> ListT m b -> ListT m c Source # munzip :: ListT m (a, b) -> ( ListT m a, ListT m b) Source #
MonadIO m => MonadIO ( ListT m) Source #
Instance details Defined in Control.Monad.Trans.List Methods liftIO :: IO a -> ListT m a Source #
Applicative m => Alternative ( ListT m) Source #
Instance details Defined in Control.Monad.Trans.List Methods empty :: ListT m a Source # (<\|>) :: ListT m a -> ListT m a -> ListT m a Source # some :: ListT m a -> ListT m [a] Source # many :: ListT m a -> ListT m [a] Source #
Monad m => MonadPlus ( ListT m) Source #
Instance details Defined in Control.Monad.Trans.List Methods mzero :: ListT m a Source # mplus :: ListT m a -> ListT m a -> ListT m a Source #
( Eq1 m, Eq a) => Eq ( ListT m a) Source #
Instance details Defined in Control.Monad.Trans.List Methods (==) :: ListT m a -> ListT m a -> Bool Source # (/=) :: ListT m a -> ListT m a -> Bool Source #
( Ord1 m, Ord a) => Ord ( ListT m a) Source #
Instance details Defined in Control.Monad.Trans.List Methods compare :: ListT m a -> ListT m a -> Ordering Source # (<) :: ListT m a -> ListT m a -> Bool Source # (<=) :: ListT m a -> ListT m a -> Bool Source # (>) :: ListT m a -> ListT m a -> Bool Source # (>=) :: ListT m a -> ListT m a -> Bool Source # max :: ListT m a -> ListT m a -> ListT m a Source # min :: ListT m a -> ListT m a -> ListT m a Source #
( Read1 m, Read a) => Read ( ListT m a) Source #
Instance details Defined in Control.Monad.Trans.List Methods readsPrec :: Int -> ReadS ( ListT m a) Source # readList :: ReadS [ ListT m a] Source # readPrec :: ReadPrec ( ListT m a) Source # readListPrec :: ReadPrec [ ListT m a] Source #
( Show1 m, Show a) => Show ( ListT m a) Source #
Instance details Defined in Control.Monad.Trans.List Methods showsPrec :: Int -> ListT m a -> ShowS Source # show :: ListT m a -> String Source # showList :: [ ListT m a] -> ShowS Source #

mapListT :: (m [a] -> n [b]) -> ListT m a -> ListT n b Source #

Map between ListT computations.

runListT (mapListT f m) = f (runListT m)

Lifting other operations

liftCallCC :: CallCC m [a] [b] -> CallCC ( ListT m) a b Source #

Lift a callCC operation to the new monad.

liftCatch :: Catch e m [a] -> Catch e ( ListT m) a Source #

Lift a catchE operation to the new monad.