Control.Monad.STM.Unlift

A typeclass which abstracts over monads that can be "unlifted" back down to STM. (This is essentially a copy of Control.Monad.IO.Unlift, modified for the STM monad.)

In a manner that is analagous to MonadUnliftIO, instances of this typeclass are essentially limited to:

• The STM monad itself
• Monad transformer stacks based on ReaderT or IdentityT, with STM at the "bottom".

Documentation

class MonadSTM m => MonadUnliftSTM m where

Analagous to MonadUnliftIO. (It is an abstraction for monads that can be "unlifted" back down to the STM monad.)

Minimal complete definition

askUnliftSTM | withRunInSTM

Methods

askUnliftSTM :: m (UnliftSTM m)

withRunInSTM :: ((forall a. m a -> STM a) -> STM b) -> m b

Instances

MonadUnliftSTM STM

Defined in Control.Monad.STM.Unlift

Methods

askUnliftSTM :: STM (UnliftSTM STM)

withRunInSTM :: ((forall a. STM a -> STM a) -> STM b) -> STM b

MonadUnliftSTM m => MonadUnliftSTM (ReaderT r m)

Defined in Control.Monad.STM.Unlift

Methods

askUnliftSTM :: ReaderT r m (UnliftSTM (ReaderT r m))

withRunInSTM :: ((forall a. ReaderT r m a -> STM a) -> STM b) -> ReaderT r m b

MonadUnliftSTM m => MonadUnliftSTM (IdentityT m)

Defined in Control.Monad.STM.Unlift

Methods

askUnliftSTM :: IdentityT m (UnliftSTM (IdentityT m))

withRunInSTM :: ((forall a. IdentityT m a -> STM a) -> STM b) -> IdentityT m b

newtype UnliftSTM m

Analagous to UnliftIO

Constructors

UnliftSTM

Fields

• unliftSTM :: forall a. m a -> STM a

askRunInSTM :: MonadUnliftSTM m => m (m a -> STM a)

Analagous to askRunInIO

withUnliftSTM :: MonadUnliftSTM m => (UnliftSTM m -> STM a) -> m a

Analagous to withUnliftIO

toSTM :: MonadUnliftSTM m => m a -> m (STM a)

Analagous to toIO