| Copyright | (c) Andy Gill 2001 (c) Oregon Graduate Institute of Science and Technology 2001 |
|---|---|
| License | BSD-style (see the file LICENSE) |
| Maintainer | libraries@haskell.org |
| Stability | experimental |
| Portability | non-portable (multi-param classes, functional dependencies) |
| Safe Haskell | Safe |
| Language | Haskell2010 |
Control.Monad.RWS.Strict
Description
Strict RWS monad.
Inspired by the paper Functional Programming with Overloading and Higher-Order Polymorphism, Mark P Jones (http://web.cecs.pdx.edu/~mpj/) Advanced School of Functional Programming, 1995.
Synopsis
- type RWS r w s = RWST r w s Identity
- rws :: (r -> s -> (a, s, w)) -> RWS r w s a
- runRWS :: RWS r w s a -> r -> s -> (a, s, w)
- evalRWS :: RWS r w s a -> r -> s -> (a, w)
- execRWS :: RWS r w s a -> r -> s -> (s, w)
- mapRWS :: ((a, s, w) -> (b, s, w')) -> RWS r w s a -> RWS r w' s b
- withRWS :: (r' -> s -> (r, s)) -> RWS r w s a -> RWS r' w s a
- newtype RWST r w s (m :: Type -> Type) a = RWST (r -> s -> m (a, s, w))
- runRWST :: RWST r w s m a -> r -> s -> m (a, s, w)
- evalRWST :: Monad m => RWST r w s m a -> r -> s -> m (a, w)
- execRWST :: Monad m => RWST r w s m a -> r -> s -> m (s, w)
- mapRWST :: (m (a, s, w) -> n (b, s, w')) -> RWST r w s m a -> RWST r w' s n b
- withRWST :: forall r' s r w (m :: Type -> Type) a. (r' -> s -> (r, s)) -> RWST r w s m a -> RWST r' w s m a
- module Control.Monad.RWS.Class
- module Control.Monad.Trans
The RWS monad
type RWS r w s = RWST r w s Identity Source #
A monad containing an environment of type r, output of type w
and an updatable state of type s.
rws :: (r -> s -> (a, s, w)) -> RWS r w s a Source #
Construct an RWS computation from a function.
(The inverse of runRWS.)
runRWS :: RWS r w s a -> r -> s -> (a, s, w) Source #
Unwrap an RWS computation as a function.
(The inverse of rws.)
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.
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.
The RWST monad transformer
newtype RWST r w s (m :: Type -> Type) a Source #
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 (r -> s -> m (a, s, w)) |
Instances
| (Monoid w, Monad m) => MonadRWS r w s (RWST r w s m) Source # | |||||
Defined in Control.Monad.RWS.Class | |||||
| (MonadAccum w' m, Monoid w) => MonadAccum w' (RWST r w s m) Source # | Since: mtl-2.3 | ||||
| (Monoid w, MonadError e m) => MonadError e (RWST r w s m) Source # | |||||
Defined in Control.Monad.Error.Class Methods throwError :: e -> RWST r w s m a Source # catchError :: RWST r w s m a -> (e -> RWST r w s m a) -> RWST r w s m a Source # | |||||
| (Monad m, Monoid w) => MonadReader r (RWST r w s m) Source # | |||||
| (MonadSelect w' m, Monoid w) => MonadSelect w' (RWST r w s m) Source # | A combination of an 'outer' Since: mtl-2.3 | ||||
Defined in Control.Monad.Select | |||||
| (Monad m, Monoid w) => MonadState s (RWST r w s m) Source # | |||||
| (Monoid w, Monad m) => MonadWriter w (RWST r w s m) Source # | |||||
| Monoid w => MonadTrans (RWST r w s) | |||||
| (Monoid w, MonadFail m) => MonadFail (RWST r w s m) | |||||
| (Monoid w, MonadFix m) => MonadFix (RWST r w s m) | |||||
| (Monoid w, MonadIO m) => MonadIO (RWST r w s m) | |||||
| Contravariant m => Contravariant (RWST r w s m) | |||||
| (Monoid w, Functor m, MonadPlus m) => Alternative (RWST r w s m) | |||||
| (Monoid w, Functor m, Monad m) => Applicative (RWST r w s m) | |||||
Defined in Control.Monad.Trans.RWS.Strict Methods pure :: a -> RWST r w s m a Source # (<*>) :: RWST r w s m (a -> b) -> RWST r w s m a -> RWST r w s m b Source # liftA2 :: (a -> b -> c) -> RWST r w s m a -> RWST r w s m b -> RWST r w s m c Source # (*>) :: RWST r w s m a -> RWST r w s m b -> RWST r w s m b Source # (<*) :: RWST r w s m a -> RWST r w s m b -> RWST r w s m a Source # | |||||
| Functor m => Functor (RWST r w s m) | |||||
| (Monoid w, Monad m) => Monad (RWST r w s m) | |||||
| (Monoid w, MonadPlus m) => MonadPlus (RWST r w s m) | |||||
| (Monoid w, MonadCont m) => MonadCont (RWST r w s m) Source # | |||||
| Generic (RWST r w s m a) | |||||
Defined in Control.Monad.Trans.RWS.Strict Associated Types
| |||||
| type Rep (RWST r w s m a) | |||||
Defined in Control.Monad.Trans.RWS.Strict | |||||
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.
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.
withRWST :: forall r' s r w (m :: Type -> Type) a. (r' -> s -> (r, s)) -> RWST r w s m a -> RWST r' w s m a Source #
Strict Reader-writer-state monads
module Control.Monad.RWS.Class
module Control.Monad.Trans