| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
Foundation.Monad
Synopsis
- class Monad m => MonadIO (m :: Type -> Type ) where
- class Monad m => MonadFailure (m :: Type -> Type ) where
- class Monad m => MonadThrow m where
- class MonadThrow m => MonadCatch m where
-
class
MonadCatch
m =>
MonadBracket
m
where
- generalBracket :: m a -> (a -> b -> m ignored1) -> (a -> SomeException -> m ignored2) -> (a -> m b) -> m b
- class MonadTrans trans where
-
newtype
Identity
a =
Identity
{
- runIdentity :: a
- replicateM :: Applicative m => CountOf a -> m a -> m [a]
Documentation
class Monad m => MonadIO (m :: Type -> Type ) where Source #
Monads in which
IO
computations may be embedded.
Any monad built by applying a sequence of monad transformers to the
IO
monad will be an instance of this class.
Instances should satisfy the following laws, which state that
liftIO
is a transformer of monads:
class Monad m => MonadFailure (m :: Type -> Type ) where Source #
Monad that can represent failure
Similar to MonadFail but with a parametrized Failure linked to the Monad
Associated Types
type Failure (m :: Type -> Type ) Source #
The associated type with the MonadFailure, representing what failure can be encoded in this monad
Instances
| MonadFailure Maybe | |
| MonadFailure ( Either a) | |
| ( Functor m, MonadFailure m) => MonadFailure ( StateT s m) Source # | |
| MonadFailure m => MonadFailure ( ReaderT r m) Source # | |
| Monad m => MonadFailure ( ExceptT e m) Source # | |
| MonadFailure m => MonadFailure ( Conduit i o m) Source # | |
| Monad state => MonadFailure ( Builder collection mutCollection step state err) | |
class Monad m => MonadThrow m where Source #
Monad that can throw exception
Methods
throw :: Exception e => e -> m a Source #
Throw immediatity an exception.
Only a
MonadCatch
monad will be able to catch the exception using
catch
Instances
| MonadThrow IO Source # | |
| MonadThrow m => MonadThrow ( ResourceT m) Source # | |
| ( Functor m, MonadThrow m) => MonadThrow ( StateT s m) Source # | |
| MonadThrow m => MonadThrow ( ReaderT r m) Source # | |
| MonadThrow m => MonadThrow ( Conduit i o m) Source # | |
class MonadThrow m => MonadCatch m where Source #
Monad that can catch exception
Instances
| MonadCatch IO Source # | |
| MonadCatch m => MonadCatch ( ResourceT m) Source # | |
| ( Functor m, MonadCatch m) => MonadCatch ( StateT s m) Source # | |
| MonadCatch m => MonadCatch ( ReaderT r m) Source # | |
| MonadCatch m => MonadCatch ( Conduit i o m) Source # | |
class MonadCatch m => MonadBracket m where Source #
Monad that can ensure cleanup actions are performed even in the case of exceptions, both synchronous and asynchronous. This usually excludes continuation-based monads.
Methods
Arguments
| :: m a |
acquire some resource |
| -> (a -> b -> m ignored1) |
cleanup, no exception thrown |
| -> (a -> SomeException -> m ignored2) |
cleanup, some exception thrown. The exception will be rethrown |
| -> (a -> m b) |
inner action to perform with the resource |
| -> m b |
A generalized version of the standard bracket function which allows distinguishing different exit cases.
Instances
| MonadBracket IO Source # | |
|
Defined in Foundation.Monad.Exception Methods generalBracket :: IO a -> (a -> b -> IO ignored1) -> (a -> SomeException -> IO ignored2) -> (a -> IO b) -> IO b Source # |
|
| MonadBracket m => MonadBracket ( ResourceT m) Source # | |
|
Defined in Foundation.Conduit.Internal Methods generalBracket :: ResourceT m a -> (a -> b -> ResourceT m ignored1) -> (a -> SomeException -> ResourceT m ignored2) -> (a -> ResourceT m b) -> ResourceT m b Source # |
|
| MonadBracket m => MonadBracket ( ReaderT r m) Source # | |
|
Defined in Foundation.Monad.Reader Methods generalBracket :: ReaderT r m a -> (a -> b -> ReaderT r m ignored1) -> (a -> SomeException -> ReaderT r m ignored2) -> (a -> ReaderT r m b) -> ReaderT r m b Source # |
|
class MonadTrans trans where Source #
Basic Transformer class
Methods
lift :: Monad m => m a -> trans m a Source #
Lift a computation from an inner monad to the current transformer monad
Instances
| MonadTrans ResourceT Source # | |
| MonadTrans ( StateT s) Source # | |
| MonadTrans ( ReaderT r) Source # | |
| MonadTrans ( ExceptT e) Source # | |
| MonadTrans ( Conduit i o) Source # | |
Identity functor and monad. (a non-strict monad)
Since: base-4.8.0.0
Constructors
| Identity | |
|
Fields
|
|
Instances
replicateM :: Applicative m => CountOf a -> m a -> m [a] Source #
performs the action
replicateM
n act
n
times,
gathering the results.