| Portability | non-portable (multi-param classes, functional dependencies) |
|---|---|
| Stability | experimental |
| Maintainer | ross@soi.city.ac.uk |
Control.Monad.RWS.Lazy
Description
Lazy 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.
- type RWS r w s = RWST r w s Identity
- 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 a = RWST {
- runRWST :: 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 :: (r' -> s -> (r, s)) -> RWST r w s m a -> RWST r' w s m a
- module Control.Monad.RWS.Class
- module Control.Monad
- module Control.Monad.Fix
- module Control.Monad.Trans
- module Data.Monoid
The RWS monad
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.
runRWS :: RWS r w s a -> r -> s -> (a, s, w)
Unwrap an RWS computation as a function.
(The inverse of rws.)
The RWST monad transformer
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.
Instances
| (Monoid w, Monad m) => MonadRWS r w s (RWST r w s m) | |
| (Monoid w, Monad m) => MonadWriter w (RWST r w s m) | |
| (Monad m, Monoid w) => MonadState s (RWST r w s m) | |
| (Monad m, Monoid w) => MonadReader r (RWST r w s m) | |
| (Monoid w, MonadError e m) => MonadError e (RWST r w s m) | |
| Monoid w => MonadTrans (RWST r w s) | |
| (Monoid w, Monad m) => Monad (RWST r w s m) | |
| Functor m => Functor (RWST r w s m) | |
| (Monoid w, MonadFix m) => MonadFix (RWST r w s m) | |
| (Monoid w, MonadPlus m) => MonadPlus (RWST r w s m) | |
| (Monoid w, Functor m, Monad m) => Applicative (RWST r w s m) | |
| (Monoid w, Functor m, MonadPlus m) => Alternative (RWST r w s m) | |
| (Monoid w, MonadIO m) => MonadIO (RWST r w s m) | |
| (Monoid w, MonadCont m) => MonadCont (RWST r w s m) |
Lazy Reader-writer-state monads
module Control.Monad.RWS.Class
module Control.Monad
module Control.Monad.Fix
module Control.Monad.Trans
module Data.Monoid