STMonadTrans-0.4.6: A monad transformer version of the ST monad
CopyrightJosef Svenningsson 2008-2017
(c) The University of Glasgow 1994-2000
LicenseBSD
Maintainerjosef.svenningsson@gmail.com, Andreas Abel
Stabilitystable
Portabilitynon-portable (GHC Extensions)
Safe HaskellNone
LanguageHaskell2010

Control.Monad.ST.Trans

Description

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 state token will be duplicated across the different answers and this causes 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.

Synopsis

The ST Monad Transformer

data STT s m a Source #

STT is the monad transformer providing polymorphic updateable references

Instances

Instances details
(MonadWriter w m, Functor m) => MonadWriter w (STT s m) Source # 
Instance details

Defined in Control.Monad.ST.Trans.Internal

Methods

writer :: (a, w) -> STT s m a #

tell :: w -> STT s m () #

listen :: STT s m a -> STT s m (a, w) #

pass :: STT s m (a, w -> w) -> STT s m a #

(MonadState s m, Functor m) => MonadState s (STT s1 m) Source # 
Instance details

Defined in Control.Monad.ST.Trans.Internal

Methods

get :: STT s1 m s #

put :: s -> STT s1 m () #

state :: (s -> (a, s)) -> STT s1 m a #

(MonadReader r m, Functor m) => MonadReader r (STT s m) Source # 
Instance details

Defined in Control.Monad.ST.Trans.Internal

Methods

ask :: STT s m r #

local :: (r -> r) -> STT s m a -> STT s m a #

reader :: (r -> a) -> STT s m a #

(MonadError e m, Functor m) => MonadError e (STT s m) Source # 
Instance details

Defined in Control.Monad.ST.Trans.Internal

Methods

throwError :: e -> STT s m a #

catchError :: STT s m a -> (e -> STT s m a) -> STT s m a #

MonadTrans (STT s) Source # 
Instance details

Defined in Control.Monad.ST.Trans.Internal

Methods

lift :: Monad m => m a -> STT s m a #

(Applicative m, Monad m) => MArray (STUArray s) Word64 (STT s m) Source # 
Instance details

Defined in Control.Monad.ST.Trans.Internal

Methods

getBounds :: Ix i => STUArray s i Word64 -> STT s m (i, i) #

getNumElements :: Ix i => STUArray s i Word64 -> STT s m Int

newArray :: Ix i => (i, i) -> Word64 -> STT s m (STUArray s i Word64) #

newArray_ :: Ix i => (i, i) -> STT s m (STUArray s i Word64) #

unsafeNewArray_ :: Ix i => (i, i) -> STT s m (STUArray s i Word64)

unsafeRead :: Ix i => STUArray s i Word64 -> Int -> STT s m Word64

unsafeWrite :: Ix i => STUArray s i Word64 -> Int -> Word64 -> STT s m ()

(Applicative m, Monad m) => MArray (STUArray s) Word32 (STT s m) Source # 
Instance details

Defined in Control.Monad.ST.Trans.Internal

Methods

getBounds :: Ix i => STUArray s i Word32 -> STT s m (i, i) #

getNumElements :: Ix i => STUArray s i Word32 -> STT s m Int

newArray :: Ix i => (i, i) -> Word32 -> STT s m (STUArray s i Word32) #

newArray_ :: Ix i => (i, i) -> STT s m (STUArray s i Word32) #

unsafeNewArray_ :: Ix i => (i, i) -> STT s m (STUArray s i Word32)

unsafeRead :: Ix i => STUArray s i Word32 -> Int -> STT s m Word32

unsafeWrite :: Ix i => STUArray s i Word32 -> Int -> Word32 -> STT s m ()

(Applicative m, Monad m) => MArray (STUArray s) Word16 (STT s m) Source # 
Instance details

Defined in Control.Monad.ST.Trans.Internal

Methods

getBounds :: Ix i => STUArray s i Word16 -> STT s m (i, i) #

getNumElements :: Ix i => STUArray s i Word16 -> STT s m Int

newArray :: Ix i => (i, i) -> Word16 -> STT s m (STUArray s i Word16) #

newArray_ :: Ix i => (i, i) -> STT s m (STUArray s i Word16) #

unsafeNewArray_ :: Ix i => (i, i) -> STT s m (STUArray s i Word16)

unsafeRead :: Ix i => STUArray s i Word16 -> Int -> STT s m Word16

unsafeWrite :: Ix i => STUArray s i Word16 -> Int -> Word16 -> STT s m ()

(Applicative m, Monad m) => MArray (STUArray s) Word8 (STT s m) Source # 
Instance details

Defined in Control.Monad.ST.Trans.Internal

Methods

getBounds :: Ix i => STUArray s i Word8 -> STT s m (i, i) #

getNumElements :: Ix i => STUArray s i Word8 -> STT s m Int

newArray :: Ix i => (i, i) -> Word8 -> STT s m (STUArray s i Word8) #

newArray_ :: Ix i => (i, i) -> STT s m (STUArray s i Word8) #

unsafeNewArray_ :: Ix i => (i, i) -> STT s m (STUArray s i Word8)

unsafeRead :: Ix i => STUArray s i Word8 -> Int -> STT s m Word8

unsafeWrite :: Ix i => STUArray s i Word8 -> Int -> Word8 -> STT s m ()

(Applicative m, Monad m) => MArray (STUArray s) Int64 (STT s m) Source # 
Instance details

Defined in Control.Monad.ST.Trans.Internal

Methods

getBounds :: Ix i => STUArray s i Int64 -> STT s m (i, i) #

getNumElements :: Ix i => STUArray s i Int64 -> STT s m Int

newArray :: Ix i => (i, i) -> Int64 -> STT s m (STUArray s i Int64) #

newArray_ :: Ix i => (i, i) -> STT s m (STUArray s i Int64) #

unsafeNewArray_ :: Ix i => (i, i) -> STT s m (STUArray s i Int64)

unsafeRead :: Ix i => STUArray s i Int64 -> Int -> STT s m Int64

unsafeWrite :: Ix i => STUArray s i Int64 -> Int -> Int64 -> STT s m ()

(Applicative m, Monad m) => MArray (STUArray s) Int32 (STT s m) Source # 
Instance details

Defined in Control.Monad.ST.Trans.Internal

Methods

getBounds :: Ix i => STUArray s i Int32 -> STT s m (i, i) #

getNumElements :: Ix i => STUArray s i Int32 -> STT s m Int

newArray :: Ix i => (i, i) -> Int32 -> STT s m (STUArray s i Int32) #

newArray_ :: Ix i => (i, i) -> STT s m (STUArray s i Int32) #

unsafeNewArray_ :: Ix i => (i, i) -> STT s m (STUArray s i Int32)

unsafeRead :: Ix i => STUArray s i Int32 -> Int -> STT s m Int32

unsafeWrite :: Ix i => STUArray s i Int32 -> Int -> Int32 -> STT s m ()

(Applicative m, Monad m) => MArray (STUArray s) Int16 (STT s m) Source # 
Instance details

Defined in Control.Monad.ST.Trans.Internal

Methods

getBounds :: Ix i => STUArray s i Int16 -> STT s m (i, i) #

getNumElements :: Ix i => STUArray s i Int16 -> STT s m Int

newArray :: Ix i => (i, i) -> Int16 -> STT s m (STUArray s i Int16) #

newArray_ :: Ix i => (i, i) -> STT s m (STUArray s i Int16) #

unsafeNewArray_ :: Ix i => (i, i) -> STT s m (STUArray s i Int16)

unsafeRead :: Ix i => STUArray s i Int16 -> Int -> STT s m Int16

unsafeWrite :: Ix i => STUArray s i Int16 -> Int -> Int16 -> STT s m ()

(Applicative m, Monad m) => MArray (STUArray s) Int8 (STT s m) Source # 
Instance details

Defined in Control.Monad.ST.Trans.Internal

Methods

getBounds :: Ix i => STUArray s i Int8 -> STT s m (i, i) #

getNumElements :: Ix i => STUArray s i Int8 -> STT s m Int

newArray :: Ix i => (i, i) -> Int8 -> STT s m (STUArray s i Int8) #

newArray_ :: Ix i => (i, i) -> STT s m (STUArray s i Int8) #

unsafeNewArray_ :: Ix i => (i, i) -> STT s m (STUArray s i Int8)

unsafeRead :: Ix i => STUArray s i Int8 -> Int -> STT s m Int8

unsafeWrite :: Ix i => STUArray s i Int8 -> Int -> Int8 -> STT s m ()

(Applicative m, Monad m) => MArray (STUArray s) Double (STT s m) Source # 
Instance details

Defined in Control.Monad.ST.Trans.Internal

Methods

getBounds :: Ix i => STUArray s i Double -> STT s m (i, i) #

getNumElements :: Ix i => STUArray s i Double -> STT s m Int

newArray :: Ix i => (i, i) -> Double -> STT s m (STUArray s i Double) #

newArray_ :: Ix i => (i, i) -> STT s m (STUArray s i Double) #

unsafeNewArray_ :: Ix i => (i, i) -> STT s m (STUArray s i Double)

unsafeRead :: Ix i => STUArray s i Double -> Int -> STT s m Double

unsafeWrite :: Ix i => STUArray s i Double -> Int -> Double -> STT s m ()

(Applicative m, Monad m) => MArray (STUArray s) Float (STT s m) Source # 
Instance details

Defined in Control.Monad.ST.Trans.Internal

Methods

getBounds :: Ix i => STUArray s i Float -> STT s m (i, i) #

getNumElements :: Ix i => STUArray s i Float -> STT s m Int

newArray :: Ix i => (i, i) -> Float -> STT s m (STUArray s i Float) #

newArray_ :: Ix i => (i, i) -> STT s m (STUArray s i Float) #

unsafeNewArray_ :: Ix i => (i, i) -> STT s m (STUArray s i Float)

unsafeRead :: Ix i => STUArray s i Float -> Int -> STT s m Float

unsafeWrite :: Ix i => STUArray s i Float -> Int -> Float -> STT s m ()

(Applicative m, Monad m) => MArray (STUArray s) Word (STT s m) Source # 
Instance details

Defined in Control.Monad.ST.Trans.Internal

Methods

getBounds :: Ix i => STUArray s i Word -> STT s m (i, i) #

getNumElements :: Ix i => STUArray s i Word -> STT s m Int

newArray :: Ix i => (i, i) -> Word -> STT s m (STUArray s i Word) #

newArray_ :: Ix i => (i, i) -> STT s m (STUArray s i Word) #

unsafeNewArray_ :: Ix i => (i, i) -> STT s m (STUArray s i Word)

unsafeRead :: Ix i => STUArray s i Word -> Int -> STT s m Word

unsafeWrite :: Ix i => STUArray s i Word -> Int -> Word -> STT s m ()

(Applicative m, Monad m) => MArray (STUArray s) Int (STT s m) Source # 
Instance details

Defined in Control.Monad.ST.Trans.Internal

Methods

getBounds :: Ix i => STUArray s i Int -> STT s m (i, i) #

getNumElements :: Ix i => STUArray s i Int -> STT s m Int

newArray :: Ix i => (i, i) -> Int -> STT s m (STUArray s i Int) #

newArray_ :: Ix i => (i, i) -> STT s m (STUArray s i Int) #

unsafeNewArray_ :: Ix i => (i, i) -> STT s m (STUArray s i Int)

unsafeRead :: Ix i => STUArray s i Int -> Int -> STT s m Int

unsafeWrite :: Ix i => STUArray s i Int -> Int -> Int -> STT s m ()

(Applicative m, Monad m) => MArray (STUArray s) Char (STT s m) Source # 
Instance details

Defined in Control.Monad.ST.Trans.Internal

Methods

getBounds :: Ix i => STUArray s i Char -> STT s m (i, i) #

getNumElements :: Ix i => STUArray s i Char -> STT s m Int

newArray :: Ix i => (i, i) -> Char -> STT s m (STUArray s i Char) #

newArray_ :: Ix i => (i, i) -> STT s m (STUArray s i Char) #

unsafeNewArray_ :: Ix i => (i, i) -> STT s m (STUArray s i Char)

unsafeRead :: Ix i => STUArray s i Char -> Int -> STT s m Char

unsafeWrite :: Ix i => STUArray s i Char -> Int -> Char -> STT s m ()

(Applicative m, Monad m) => MArray (STUArray s) Bool (STT s m) Source # 
Instance details

Defined in Control.Monad.ST.Trans.Internal

Methods

getBounds :: Ix i => STUArray s i Bool -> STT s m (i, i) #

getNumElements :: Ix i => STUArray s i Bool -> STT s m Int

newArray :: Ix i => (i, i) -> Bool -> STT s m (STUArray s i Bool) #

newArray_ :: Ix i => (i, i) -> STT s m (STUArray s i Bool) #

unsafeNewArray_ :: Ix i => (i, i) -> STT s m (STUArray s i Bool)

unsafeRead :: Ix i => STUArray s i Bool -> Int -> STT s m Bool

unsafeWrite :: Ix i => STUArray s i Bool -> Int -> Bool -> STT s m ()

(Applicative m, Monad m) => MArray (STArray s) e (STT s m) Source # 
Instance details

Defined in Control.Monad.ST.Trans.Internal

Methods

getBounds :: Ix i => STArray s i e -> STT s m (i, i) #

getNumElements :: Ix i => STArray s i e -> STT s m Int

newArray :: Ix i => (i, i) -> e -> STT s m (STArray s i e) #

newArray_ :: Ix i => (i, i) -> STT s m (STArray s i e) #

unsafeNewArray_ :: Ix i => (i, i) -> STT s m (STArray s i e)

unsafeRead :: Ix i => STArray s i e -> Int -> STT s m e

unsafeWrite :: Ix i => STArray s i e -> Int -> e -> STT s m ()

(Applicative m, Monad m) => MArray (STUArray s) (StablePtr a) (STT s m) Source # 
Instance details

Defined in Control.Monad.ST.Trans.Internal

Methods

getBounds :: Ix i => STUArray s i (StablePtr a) -> STT s m (i, i) #

getNumElements :: Ix i => STUArray s i (StablePtr a) -> STT s m Int

newArray :: Ix i => (i, i) -> StablePtr a -> STT s m (STUArray s i (StablePtr a)) #

newArray_ :: Ix i => (i, i) -> STT s m (STUArray s i (StablePtr a)) #

unsafeNewArray_ :: Ix i => (i, i) -> STT s m (STUArray s i (StablePtr a))

unsafeRead :: Ix i => STUArray s i (StablePtr a) -> Int -> STT s m (StablePtr a)

unsafeWrite :: Ix i => STUArray s i (StablePtr a) -> Int -> StablePtr a -> STT s m ()

(Applicative m, Monad m) => MArray (STUArray s) (FunPtr a) (STT s m) Source # 
Instance details

Defined in Control.Monad.ST.Trans.Internal

Methods

getBounds :: Ix i => STUArray s i (FunPtr a) -> STT s m (i, i) #

getNumElements :: Ix i => STUArray s i (FunPtr a) -> STT s m Int

newArray :: Ix i => (i, i) -> FunPtr a -> STT s m (STUArray s i (FunPtr a)) #

newArray_ :: Ix i => (i, i) -> STT s m (STUArray s i (FunPtr a)) #

unsafeNewArray_ :: Ix i => (i, i) -> STT s m (STUArray s i (FunPtr a))

unsafeRead :: Ix i => STUArray s i (FunPtr a) -> Int -> STT s m (FunPtr a)

unsafeWrite :: Ix i => STUArray s i (FunPtr a) -> Int -> FunPtr a -> STT s m ()

(Applicative m, Monad m) => MArray (STUArray s) (Ptr a) (STT s m) Source # 
Instance details

Defined in Control.Monad.ST.Trans.Internal

Methods

getBounds :: Ix i => STUArray s i (Ptr a) -> STT s m (i, i) #

getNumElements :: Ix i => STUArray s i (Ptr a) -> STT s m Int

newArray :: Ix i => (i, i) -> Ptr a -> STT s m (STUArray s i (Ptr a)) #

newArray_ :: Ix i => (i, i) -> STT s m (STUArray s i (Ptr a)) #

unsafeNewArray_ :: Ix i => (i, i) -> STT s m (STUArray s i (Ptr a))

unsafeRead :: Ix i => STUArray s i (Ptr a) -> Int -> STT s m (Ptr a)

unsafeWrite :: Ix i => STUArray s i (Ptr a) -> Int -> Ptr a -> STT s m ()

(Monad m, Functor m) => Monad (STT s m) Source # 
Instance details

Defined in Control.Monad.ST.Trans.Internal

Methods

(>>=) :: STT s m a -> (a -> STT s m b) -> STT s m b #

(>>) :: STT s m a -> STT s m b -> STT s m b #

return :: a -> STT s m a #

Functor m => Functor (STT s m) Source # 
Instance details

Defined in Control.Monad.ST.Trans.Internal

Methods

fmap :: (a -> b) -> STT s m a -> STT s m b #

(<$) :: a -> STT s m b -> STT s m a #

(MonadFix m, Functor m) => MonadFix (STT s m) Source # 
Instance details

Defined in Control.Monad.ST.Trans.Internal

Methods

mfix :: (a -> STT s m a) -> STT s m a #

(MonadFail m, Functor m) => MonadFail (STT s m) Source # 
Instance details

Defined in Control.Monad.ST.Trans.Internal

Methods

fail :: String -> STT s m a #

(Monad m, Functor m) => Applicative (STT s m) Source # 
Instance details

Defined in Control.Monad.ST.Trans.Internal

Methods

pure :: a -> STT s m a #

(<*>) :: STT s m (a -> b) -> STT s m a -> STT s m b #

liftA2 :: (a -> b -> c) -> STT s m a -> STT s m b -> STT s m c #

(*>) :: STT s m a -> STT s m b -> STT s m b #

(<*) :: STT s m a -> STT s m b -> STT s m a #

runST :: Monad m => (forall s. STT s m a) -> m a Source #

Deprecated: Use runSTT instead

Executes a computation in the STT monad transformer

runSTT :: Monad m => (forall s. STT s m a) -> m a Source #

Executes a computation in the STT monad transformer

Mutable references

data STRef s a #

a value of type STRef s a is a mutable variable in state thread s, containing a value of type a

>>> :{
runST (do
    ref <- newSTRef "hello"
    x <- readSTRef ref
    writeSTRef ref (x ++ "world")
    readSTRef ref )
:}
"helloworld"

Instances

Instances details
Eq (STRef s a)

Pointer equality.

Since: base-2.1

Instance details

Defined in GHC.STRef

Methods

(==) :: STRef s a -> STRef s a -> Bool #

(/=) :: STRef s a -> STRef s a -> Bool #

newSTRef :: Applicative m => a -> STT s m (STRef s a) Source #

Create a new reference

readSTRef :: Applicative m => STRef s a -> STT s m a Source #

Reads the value of a reference

writeSTRef :: Applicative m => STRef s a -> a -> STT s m () Source #

Modifies the value of a reference

Mutable arrays

data STArray s i e #

Mutable, boxed, non-strict arrays in the ST monad. The type arguments are as follows:

  • s: the state variable argument for the ST type
  • i: the index type of the array (should be an instance of Ix)
  • e: the element type of the array.

Instances

Instances details
MArray (STArray s) e (ST s) 
Instance details

Defined in Data.Array.Base

Methods

getBounds :: Ix i => STArray s i e -> ST s (i, i) #

getNumElements :: Ix i => STArray s i e -> ST s Int

newArray :: Ix i => (i, i) -> e -> ST s (STArray s i e) #

newArray_ :: Ix i => (i, i) -> ST s (STArray s i e) #

unsafeNewArray_ :: Ix i => (i, i) -> ST s (STArray s i e)

unsafeRead :: Ix i => STArray s i e -> Int -> ST s e

unsafeWrite :: Ix i => STArray s i e -> Int -> e -> ST s ()

MArray (STArray s) e (ST s) 
Instance details

Defined in Data.Array.Base

Methods

getBounds :: Ix i => STArray s i e -> ST s (i, i) #

getNumElements :: Ix i => STArray s i e -> ST s Int

newArray :: Ix i => (i, i) -> e -> ST s (STArray s i e) #

newArray_ :: Ix i => (i, i) -> ST s (STArray s i e) #

unsafeNewArray_ :: Ix i => (i, i) -> ST s (STArray s i e)

unsafeRead :: Ix i => STArray s i e -> Int -> ST s e

unsafeWrite :: Ix i => STArray s i e -> Int -> e -> ST s ()

(Applicative m, Monad m) => MArray (STArray s) e (STT s m) Source # 
Instance details

Defined in Control.Monad.ST.Trans.Internal

Methods

getBounds :: Ix i => STArray s i e -> STT s m (i, i) #

getNumElements :: Ix i => STArray s i e -> STT s m Int

newArray :: Ix i => (i, i) -> e -> STT s m (STArray s i e) #

newArray_ :: Ix i => (i, i) -> STT s m (STArray s i e) #

unsafeNewArray_ :: Ix i => (i, i) -> STT s m (STArray s i e)

unsafeRead :: Ix i => STArray s i e -> Int -> STT s m e

unsafeWrite :: Ix i => STArray s i e -> Int -> e -> STT s m ()

Eq (STArray s i e)

Since: base-2.1

Instance details

Defined in GHC.Arr

Methods

(==) :: STArray s i e -> STArray s i e -> Bool #

(/=) :: STArray s i e -> STArray s i e -> Bool #

newSTArray :: (Ix i, Applicative m) => (i, i) -> e -> STT s m (STArray s i e) Source #

Creates a new mutable array

readSTArray :: (Ix i, Applicative m) => STArray s i e -> i -> STT s m e Source #

Retrieves an element from the array

writeSTArray :: (Ix i, Applicative 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 :: Applicative m => STArray s i e -> STT s m (Array i e) Source #

Copy a mutable array and turn it into an immutable array

thawSTArray :: Applicative m => Array i e -> STT s m (STArray s i e) Source #

Copy an immutable array and turn it into a mutable array

runSTArray :: 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

unsafeReadSTArray :: Applicative m => STArray s i e -> Int -> STT s m e Source #

unsafeWriteSTArray :: Applicative m => STArray s i e -> Int -> e -> STT s m () Source #

unsafeIOToSTT :: (Monad m, Functor m) => IO a -> STT s m a Source #

unsafeSTToIO :: STT s IO a -> IO a Source #

Deprecated: Use unsafeSTTToIO instead