Copyright | Josef Svenningsson 2008-2010 (c) The University of Glasgow, 1994-2000 |
---|---|
License | BSD |
Maintainer | mckean.kylej@gmail.com |
Stability | experimental |
Portability | non-portable (GHC Extensions) |
Safe Haskell | None |
Language | Haskell2010 |
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
- runSTT :: Monad m => (forall s. STT s m a) -> m a
- fixSTT :: MonadFix m => (a -> STT s m a) -> STT s m a
- newSTTRef :: Monad m => a -> STT s m (STRef s a)
- readSTTRef :: Monad m => STRef s a -> STT s m a
- writeSTTRef :: Monad m => STRef s a -> a -> STT s m ()
- newSTTArray :: (Ix i, Monad m) => (i, i) -> e -> STT s m (STArray s i e)
- readSTTArray :: (Ix i, Monad m) => STArray s i e -> i -> STT s m e
- writeSTTArray :: (Ix i, Monad m) => STArray s i e -> i -> e -> STT s m ()
- freezeSTTArray :: (Ix i, Monad m) => STArray s i e -> STT s m (Array i e)
- thawSTTArray :: (Ix i, Monad m) => Array i e -> STT s m (STArray s i e)
- runSTTArray :: (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
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) # | |
Monad m => PrimMonad (STT s m) # | |
type PrimState (STT s m) # | |
runSTT :: Monad m => (forall s. STT s m a) -> m a #
Executes a computation in the STT
monad transformer
fixSTT :: MonadFix m => (a -> STT s m a) -> STT s m a #
Allow the result of a state transformer computation to be used (lazily) inside the computation. Note that if f is strict, fixSTT f = _|_.
Mutable references
readSTTRef :: Monad m => STRef s a -> STT s m a #
Reads the value of a reference
writeSTTRef :: Monad m => STRef s a -> a -> STT s m () #
Modifies the value of a reference
Mutable arrays
newSTTArray :: (Ix i, Monad m) => (i, i) -> e -> STT s m (STArray s i e) #
Creates a new mutable array
readSTTArray :: (Ix i, Monad m) => STArray s i e -> i -> STT s m e #
Retrieves an element from the array
writeSTTArray :: (Ix i, Monad m) => STArray s i e -> i -> e -> STT s m () #
Modifies an element in the array
freezeSTTArray :: (Ix i, Monad m) => STArray s i e -> STT s m (Array i e) #
Copy a mutable array and turn it into an immutable array
thawSTTArray :: (Ix i, Monad m) => Array i e -> STT s m (STArray s i e) #
Copy an immutable array and turn it into a mutable array
runSTTArray :: (Ix i, Monad m) => (forall s. STT s m (STArray s i e)) -> m (Array i e) #
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 #
unsafeSTToIO :: STT s IO a -> IO a #