Control.Monad.RWS.Concurrent.Lazy

Concurrent RWS monad, combining a Reader, a Writer, and a State monad.

This module performs computations lazily. For a strict version, see Control.Monad.RWS.Concurrent.Strict.

Documentation

module Control.Monad.RWS

The RWSC monad transformer

data RWSC r w s m a

A concurrent monad transformer reading an environment of type r, collecting output of type w and updating a state of type s to an inner monad m.

This is very similar to transformers' RWST, with the exception of the MonadIO constraint on every instance, which is necessary to perform STM actions.

Instances

(Monoid w, MonadIO m, MonadReader r m, MonadWriter w m, MonadState s m) => MonadRWS r w s (RWSC r w s m)

MonadReader r m => MonadReader r (RWSC r w s m)

(MonadIO m, MonadState s m) => MonadState s (RWSC r w s m)

(Monoid w, MonadIO m, MonadWriter w m) => MonadWriter w (RWSC r w s m)

MonadTrans (RWSC r w s)

Monad m => Monad (RWSC r w s m)

Functor m => Functor (RWSC r w s m)

MonadFix m => MonadFix (RWSC r w s m)

MonadPlus m => MonadPlus (RWSC r w s m)

(Functor m, Monad m) => Applicative (RWSC r w s m)

(Functor m, MonadPlus m) => Alternative (RWSC r w s m)

(MonadIO m, MonadCatch m) => MonadCatch (RWSC r w s m)

MonadIO m => MonadIO (RWSC r w s m)

MonadFork m => MonadFork (RWSC r w s m)

Running RWSC actions

runRWSC

Arguments

:: MonadIO m

=> RWSC r w s m a

computation to execute

-> r

environment to read

-> TVar s

state to modify

-> TVar w

output channel

-> m (a, s, w)

return value, final state, and collected output

Unwrap a concurrent RWS monad computation as a function.

evalRWSC

Arguments

:: MonadIO m

=> RWSC r w s m a

computation to execute

-> r

environment to read

-> TVar s

state to modify

-> TVar w

output channel

-> m (a, w)

return value and collected output

Unwrap a concurrent RWS monad computation as a function, discarding the final state.

execRWSC

Arguments

:: MonadIO m

=> RWSC r w s m a

computation to execute

-> r

environment to read

-> TVar s

state to modify

-> TVar w

output channel

-> m (s, w)

final state and collected output

Unwrap a concurrent RWS monad computation as a function, discarding the return value.

mapRWSC :: (m (a, TVar s, TVar w) -> n (b, TVar s, TVar w)) -> RWSC r w s m a -> RWSC r w s n b

Map the inner computation using the given function.

• runRWSC (mapRWSC f m) r w s = f (runRWSC m r w s)

withRWSC :: (r' -> TVar s -> TVar w -> (r, TVar s, TVar w)) -> RWSC r w s m a -> RWSC r' w s m a

withRWSC f m executes action m with an initial environment and state modified by applying f.

• runRWSC (withRWSC f m) r s w = uncurry3 (runRWSC m) (f r s w)

Lifting other operations

liftCallCCC :: ((((a, TVar s, TVar w) -> m (b, TVar s, TVar w)) -> m (a, TVar s, TVar w)) -> m (a, TVar s, TVar w)) -> ((a -> RWSC r w s m b) -> RWSC r w s m a) -> RWSC r w s m a

Uniform lifting of a callCC operation to the new monad.

liftCatch :: (m (a, TVar s, TVar w) -> (e -> m (a, TVar s, TVar w)) -> m (a, TVar s, TVar w)) -> RWSC l w s m a -> (e -> RWSC l w s m a) -> RWSC l w s m a

Lift a catchError operation to the new monad.