Copyright | Josef Svenningsson 2008-2010 (c) The University of Glasgow, 1994-2000 |
---|---|
License | BSD |
Maintainer | josef.svenningsson@gmail.com |
Stability | experimental |
Portability | non-portable (GHC Extensions) |
Safe Haskell | None |
Language | Haskell98 |
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 a Source
Executes a computation in the STT
monad transformer
Mutable references
writeSTRef :: Monad m => STRef s a -> a -> STT s m () Source
Modifies the value of a reference
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 e Source
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 -> Int Source
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 a Source
unsafeSTToIO :: STT s IO a -> IO a Source
unsafeSTRefToIORef :: STRef s a -> IORef a Source
unsafeIORefToSTRef :: IORef a -> STRef s a Source