Copyright	(c) Andy Gill 2001 (c) Oregon Graduate Institute of Science and Technology 2001
License	BSD-style (see the file libraries/base/LICENSE)
Maintainer	libraries@haskell.org
Stability	experimental
Portability	non-portable (multi-param classes, functional dependencies)
Safe Haskell	Safe
Language	Haskell2010

Control.Monad.RWS.Lazy

Description

Lazy RWS monad.

Inspired by the paper /Functional Programming with Overloading and Higher-Order Polymorphism/, Mark P Jones (http://www.cse.ogi.edu/~mpj/) Advanced School of Functional Programming, 1995.

Synopsis

Documentation

type RWS r w s = RWST r w s Identity #

A monad containing an environment of type r, output of type w and an updatable state of type s.

evalRWS #

Arguments

:: RWS r w s a	RWS computation to execute
-> r	initial environment
-> s	initial value
-> (a, w)	final value and output

Evaluate a computation with the given initial state and environment, returning the final value and output, discarding the final state.

execRWS #

Arguments

:: RWS r w s a	RWS computation to execute
-> r	initial environment
-> s	initial value
-> (s, w)	final state and output

Evaluate a computation with the given initial state and environment, returning the final state and output, discarding the final value.

mapRWS :: ((a, s, w) -> (b, s, w')) -> RWS r w s a -> RWS r w' s b #

Map the return value, final state and output of a computation using the given function.

runRWS (mapRWS f m) r s = f (runRWS m r s)

withRWS :: (r' -> s -> (r, s)) -> RWS r w s a -> RWS r' w s a #

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

runRWS (withRWS f m) r s = uncurry (runRWS m) (f r s)

newtype RWST r w s (m :: * -> *) a :: * -> * -> * -> (* -> *) -> * -> * #

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

Constructors

RWST
Fields runRWST :: r -> s -> m (a, s, w)

Instances

Monoid w => MonadTrans (RWST r w s)
Methods lift :: Monad m => m a -> RWST r w s m a #
(Monoid w, Monad m) => Monad (RWST r w s m)
Methods (>>=) :: RWST r w s m a -> (a -> RWST r w s m b) -> RWST r w s m b # (>>) :: RWST r w s m a -> RWST r w s m b -> RWST r w s m b # return :: a -> RWST r w s m a # fail :: String -> RWST r w s m a #
Functor m => Functor (RWST r w s m)
Methods fmap :: (a -> b) -> RWST r w s m a -> RWST r w s m b # (<$) :: a -> RWST r w s m b -> RWST r w s m a #
(Monoid w, MonadFix m) => MonadFix (RWST r w s m)
Methods mfix :: (a -> RWST r w s m a) -> RWST r w s m a #
(Monoid w, MonadFail m) => MonadFail (RWST r w s m)
Methods fail :: String -> RWST r w s m a #
(Monoid w, Functor m, Monad m) => Applicative (RWST r w s m)
Methods pure :: a -> RWST r w s m a # (<>) :: RWST r w s m (a -> b) -> RWST r w s m a -> RWST r w s m b # liftA2 :: (a -> b -> c) -> RWST r w s m a -> RWST r w s m b -> RWST r w s m c # (>) :: RWST r w s m a -> RWST r w s m b -> RWST r w s m b # (<*) :: RWST r w s m a -> RWST r w s m b -> RWST r w s m a #
(Monoid w, MonadIO m) => MonadIO (RWST r w s m)
Methods liftIO :: IO a -> RWST r w s m a #
(Monoid w, Functor m, MonadPlus m) => Alternative (RWST r w s m)
Methods empty :: RWST r w s m a # (<\|>) :: RWST r w s m a -> RWST r w s m a -> RWST r w s m a # some :: RWST r w s m a -> RWST r w s m [a] # many :: RWST r w s m a -> RWST r w s m [a] #
(Monoid w, MonadPlus m) => MonadPlus (RWST r w s m)
Methods mzero :: RWST r w s m a # mplus :: RWST r w s m a -> RWST r w s m a -> RWST r w s m a #
(Monoid w, Monad m) => MonadState (RWST r w s m) Source #
Associated Types type StateType (RWST r w s m :: * -> ) :: Source # Methods get :: RWST r w s m (StateType (RWST r w s m)) Source # put :: StateType (RWST r w s m) -> RWST r w s m () Source #
(Monoid w, Monad m) => MonadReader (RWST r w s m) Source #
Associated Types type EnvType (RWST r w s m :: * -> ) :: Source # Methods ask :: RWST r w s m (EnvType (RWST r w s m)) Source # local :: (EnvType (RWST r w s m) -> EnvType (RWST r w s m)) -> RWST r w s m a -> RWST r w s m a Source #
(Monoid w, MonadError m) => MonadError (RWST r w s m) Source #
Associated Types type ErrorType (RWST r w s m :: * -> ) :: Source # Methods throwError :: ErrorType (RWST r w s m) -> RWST r w s m a Source # catchError :: RWST r w s m a -> (ErrorType (RWST r w s m) -> RWST r w s m a) -> RWST r w s m a Source #
(Monoid w, MonadCont m) => MonadCont (RWST r w s m) Source #
Methods callCC :: ((a -> RWST r w s m b) -> RWST r w s m a) -> RWST r w s m a Source #
(Monoid w, Monad m) => MonadWriter (RWST r w s m) Source #
Associated Types type WritType (RWST r w s m :: * -> ) :: Source # Methods tell :: WritType (RWST r w s m) -> RWST r w s m () Source # listen :: RWST r w s m a -> RWST r w s m (a, WritType (RWST r w s m)) Source # pass :: RWST r w s m (a, WritType (RWST r w s m) -> WritType (RWST r w s m)) -> RWST r w s m a Source #
(Monoid w, Monad m) => MonadRWS (RWST r w s m) Source #

type StateType (RWST r w s m) Source #
type StateType (RWST r w s m) = s
type EnvType (RWST r w s m) Source #
type EnvType (RWST r w s m) = r
type ErrorType (RWST r w s m) Source #
type ErrorType (RWST r w s m) = ErrorType m
type WritType (RWST r w s m) Source #
type WritType (RWST r w s m) = w

evalRWST #

Arguments

:: Monad m
=> RWST r w s m a	computation to execute
-> r	initial environment
-> s	initial value
-> m (a, w)	computation yielding final value and output

Evaluate a computation with the given initial state and environment, returning the final value and output, discarding the final state.

execRWST #

Arguments

:: Monad m
=> RWST r w s m a	computation to execute
-> r	initial environment
-> s	initial value
-> m (s, w)	computation yielding final state and output

Evaluate a computation with the given initial state and environment, returning the final state and output, discarding the final value.

mapRWST :: (m (a, s, w) -> n (b, s, w')) -> RWST r w s m a -> RWST r w' s n b #

Map the inner computation using the given function.

runRWST (mapRWST f m) r s = f (runRWST m r s)

withRWST :: (r' -> s -> (r, s)) -> RWST r w s m a -> RWST r' w s m a #

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

runRWST (withRWST f m) r s = uncurry (runRWST m) (f r s)

module Control.Monad.RWS.Class

module Control.Monad

module Control.Monad.Fix

module Control.Monad.Trans

module Data.Monoid