Portability | non-portable (GHC Extensions) |
---|---|
Stability | experimental |
Maintainer | josef.svenningsson@gmail.com |
This library provides a monad transformer version of the ST monad.
Warning! This monad transformer should not be used with monads that can contain multiple answers, like the list monad. The reason is that the will be duplicated across the different answers and this cause Bad Things to happen (such as loss of referential transparency). Safe monads include the monads State, Reader, Writer, Maybe and combinations of their corresponding monad transformers.
- data STT s m a
- runST :: Monad m => (forall s. STT s m a) -> m a
- data STRef s a
- newSTRef :: Monad m => a -> STT s m (STRef s a)
- readSTRef :: Monad m => STRef s a -> STT s m a
- writeSTRef :: Monad m => STRef s a -> a -> STT s m ()
- data STArray s i e
- newSTArray :: (Ix i, Monad m) => (i, i) -> e -> STT s m (STArray s i e)
- readSTArray :: (Ix i, Monad m) => STArray s i e -> i -> STT s m e
- writeSTArray :: (Ix i, Monad m) => STArray s i e -> i -> e -> STT s m ()
- boundsSTArray :: STArray s i e -> (i, i)
- numElementsSTArray :: STArray s i e -> Int
- freezeSTArray :: (Ix i, Monad m) => STArray s i e -> STT s m (Array i e)
- thawSTArray :: (Ix i, Monad m) => Array i e -> STT s m (STArray s i e)
- runSTArray :: (Ix i, Monad m) => (forall s. STT s m (STArray s i e)) -> m (Array i e)
- unsafeIOToSTT :: Monad m => IO a -> STT s m a
- unsafeSTToIO :: STT s IO a -> IO a
- unsafeSTRefToIORef :: STRef s a -> IORef a
- unsafeIORefToSTRef :: IORef a -> STRef s a
The ST Monad Transformer
STT
is the monad transformer providing polymorphic updateable references
MonadError e m => MonadError e (STT s m) | |
MonadReader r m => MonadReader r (STT s m) | |
MonadState s m => MonadState s (STT s' m) | |
MonadWriter w m => MonadWriter w (STT s m) | |
MonadTrans (STT s) | |
Monad m => Monad (STT s m) | |
Functor m => Functor (STT s m) | |
MonadFix m => MonadFix (STT s m) | |
(Monad m, Functor m) => Applicative (STT s m) |
runST :: Monad m => (forall s. STT s m a) -> m aSource
Executes a computation in the STT
monad transformer
Mutable references
Mutable arrays
newSTArray :: (Ix i, Monad m) => (i, i) -> e -> STT s m (STArray s i e)Source
Creates a new mutable array
readSTArray :: (Ix i, Monad m) => STArray s i e -> i -> STT s m eSource
Retrieves an element from the array
writeSTArray :: (Ix i, Monad m) => STArray s i e -> i -> e -> STT s m ()Source
Modifies an element in the array
boundsSTArray :: STArray s i e -> (i, i)Source
Returns the lowest and highest indices of the array
numElementsSTArray :: STArray s i e -> IntSource
Returns the number of elements in the array
freezeSTArray :: (Ix i, Monad m) => STArray s i e -> STT s m (Array i e)Source
Copy a mutable array and turn it into an immutable array
thawSTArray :: (Ix i, Monad m) => Array i e -> STT s m (STArray s i e)Source
Copy an immutable array and turn it into a mutable array
runSTArray :: (Ix i, Monad m) => (forall s. STT s m (STArray s i e)) -> m (Array i e)Source
A safe way to create and work with a mutable array before returning an immutable array for later perusal. This function avoids copying the array before returning it.
Unsafe Operations
unsafeIOToSTT :: Monad m => IO a -> STT s m aSource
unsafeSTToIO :: STT s IO a -> IO aSource
unsafeSTRefToIORef :: STRef s a -> IORef aSource
unsafeIORefToSTRef :: IORef a -> STRef s aSource