Control.Monad.Trans.List

transformers-0.5.1.0: Concrete functor and monad transformers

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

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

MonadTrans ListT |
Methods lift :: Monad m => m a -> ListT m a Source
Monad m => Monad (ListT m) |
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 fail :: String -> ListT m a Source
Functor m => Functor (ListT m) |
Methods fmap :: (a -> b) -> ListT m a -> ListT m b Source (<$) :: a -> ListT m b -> ListT m a Source
Monad m => MonadFail (ListT m) |
Methods fail :: String -> ListT m a Source
Applicative m => Applicative (ListT m) |
Methods pure :: a -> ListT m a Source (<*>) :: ListT m (a -> b) -> ListT m a -> ListT m b 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) |
Methods fold :: Monoid m => ListT f m -> 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) |
Methods traverse :: Applicative f => (a -> f b) -> ListT f a -> f (ListT f b) Source sequenceA :: Applicative f => ListT f (f a) -> f (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
Eq1 m => Eq1 (ListT m) |
Methods liftEq :: (a -> b -> Bool) -> ListT m a -> ListT m b -> Bool Source
Ord1 m => Ord1 (ListT m) |
Methods liftCompare :: (a -> b -> Ordering) -> ListT m a -> ListT m b -> Ordering Source
Read1 m => Read1 (ListT m) |
Methods liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (ListT m a) Source liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [ListT m a] Source
Show1 m => Show1 (ListT m) |
Methods liftShowsPrec :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> Int -> ListT m a -> ShowS Source liftShowList :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> [ListT m a] -> ShowS Source
MonadIO m => MonadIO (ListT m) |
Methods liftIO :: IO a -> ListT m a Source
MonadZip m => MonadZip (ListT m) |
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
Applicative m => Alternative (ListT m) |
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) |
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) |
Methods (==) :: ListT m a -> ListT m a -> Bool (/=) :: ListT m a -> ListT m a -> Bool
(Ord1 m, Ord a) => Ord (ListT m a) |
Methods compare :: ListT m a -> ListT m a -> Ordering (<) :: ListT m a -> ListT m a -> Bool (<=) :: ListT m a -> ListT m a -> Bool (>) :: ListT m a -> ListT m a -> Bool (>=) :: ListT m a -> ListT m a -> Bool max :: ListT m a -> ListT m a -> ListT m a min :: ListT m a -> ListT m a -> ListT m a
(Read1 m, Read a) => Read (ListT m a) |
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) |
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.