Copyright	(c) The University of Glasgow 2004
License	BSD-style (see the file libraries/base/LICENSE)
Maintainer	libraries@haskell.org
Stability	experimental
Portability	non-portable (requires STM)
Safe Haskell	Trustworthy
Language	Haskell2010

Control.Monad.STM

Contents

Orphan instances

Description

Software Transactional Memory: a modular composable concurrency abstraction. See

Composable memory transactions, by Tim Harris, Simon Marlow, Simon Peyton Jones, and Maurice Herlihy, in ACM Conference on Principles and Practice of Parallel Programming 2005. https://www.microsoft.com/en-us/research/publication/composable-memory-transactions/

This module only defines the STM monad; you probably want to import Control.Concurrent.STM (which exports Control.Monad.STM).

Note that invariant checking (namely the always and alwaysSucceeds functions) has been removed. See ticket #14324 and the removal proposal. Existing users are encouraged to encapsulate their STM operations in safe abstractions which can perform the invariant checking without help from the runtime system.

Synopsis

data STM a
atomically :: STM a -> IO a
retry :: STM a
orElse :: STM a -> STM a -> STM a
check :: Bool -> STM ()
throwSTM :: Exception e => e -> STM a
catchSTM :: Exception e => STM a -> (e -> STM a) -> STM a

Documentation

data STM a #

Instances

Instances details

Alternative STM #
Instance details Defined in GHC.Internal.Conc.Sync Methods empty :: STM a # (<\|>) :: STM a -> STM a -> STM a # some :: STM a -> STM [a] # many :: STM a -> STM [a] #
Applicative STM #
Instance details Defined in GHC.Internal.Conc.Sync Methods pure :: a -> STM a # (<>) :: STM (a -> b) -> STM a -> STM b # liftA2 :: (a -> b -> c) -> STM a -> STM b -> STM c # (>) :: STM a -> STM b -> STM b # (<*) :: STM a -> STM b -> STM a #
Functor STM #
Instance details Defined in GHC.Internal.Conc.Sync Methods fmap :: (a -> b) -> STM a -> STM b # (<$) :: a -> STM b -> STM a #
Monad STM #
Instance details Defined in GHC.Internal.Conc.Sync Methods (>>=) :: STM a -> (a -> STM b) -> STM b # (>>) :: STM a -> STM b -> STM b # return :: a -> STM a #
MonadPlus STM #
Instance details Defined in GHC.Internal.Conc.Sync Methods mzero :: STM a # mplus :: STM a -> STM a -> STM a #
MonadFix STM Source #	Since: stm-2.3
Instance details Defined in Control.Monad.STM Methods mfix :: (a -> STM a) -> STM a #
MArray TArray e STM Source #
Instance details Defined in Control.Concurrent.STM.TArray Methods getBounds :: Ix i => TArray i e -> STM (i, i) Source # getNumElements :: Ix i => TArray i e -> STM Int Source # newArray :: Ix i => (i, i) -> e -> STM (TArray i e) Source # newArray_ :: Ix i => (i, i) -> STM (TArray i e) Source # unsafeNewArray_ :: Ix i => (i, i) -> STM (TArray i e) Source # unsafeRead :: Ix i => TArray i e -> Int -> STM e Source # unsafeWrite :: Ix i => TArray i e -> Int -> e -> STM () Source #
Monoid a => Monoid (STM a) #
Instance details Defined in GHC.Internal.Conc.Sync Methods mempty :: STM a # mappend :: STM a -> STM a -> STM a # mconcat :: [STM a] -> STM a #
Semigroup a => Semigroup (STM a) #
Instance details Defined in GHC.Internal.Conc.Sync Methods (<>) :: STM a -> STM a -> STM a # sconcat :: NonEmpty (STM a) -> STM a # stimes :: Integral b => b -> STM a -> STM a #

atomically :: STM a -> IO a #

retry :: STM a #

orElse :: STM a -> STM a -> STM a #

check :: Bool -> STM () Source #

Check that the boolean condition is true and, if not, retry.

In other words, check b = unless b retry.

Since: stm-2.1.1

throwSTM :: Exception e => e -> STM a #

catchSTM :: Exception e => STM a -> (e -> STM a) -> STM a #

Orphan instances

MonadFix STM Source #	Since: stm-2.3
Instance details Methods mfix :: (a -> STM a) -> STM a #