Haskell Core Libraries (base package) Contents Index

Control.Monad.ST.Lazy Portability non-portable (requires universal quantification for runST) Stability provisional Maintainer libraries@haskell.org

Contents The ST monad Unsafe operations Converting ST To IO Converting between strict and lazy ST

Description

This module presents an identical interface to Control.Monad.ST, but the underlying implementation of the state thread is lazy (in the sense that (_|_ >> a is not necessarily equal to _|_).

Synopsis

data ST s a runST :: (forall s . ST s a) -> a fixST :: (a -> ST s a) -> ST s a unsafeInterleaveST :: ST s a -> ST s a unsafeIOToST :: IO a -> ST s a stToIO :: ST RealWorld a -> IO a strictToLazyST :: ST s a -> ST s a lazyToStrictST :: ST s a -> ST s a

The ST monad

data ST s a

Instances Functor (ST s) Monad (ST s)

runST :: (forall s . ST s a) -> a

fixST :: (a -> ST s a) -> ST s a

Unsafe operations

unsafeInterleaveST :: ST s a -> ST s a

unsafeIOToST :: IO a -> ST s a

Converting ST To IO

stToIO :: ST RealWorld a -> IO a

Converting between strict and lazy ST

strictToLazyST :: ST s a -> ST s a

Convert a strict ST computation into a lazy one. The strict state thread passed to strictToLazyST is not performed until the result of the lazy state thread it returns is demanded.

lazyToStrictST :: ST s a -> ST s a

Convert a lazy ST computation into a strict one.

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