Control.Monad.RWS.CPS

Stricter RWS monad using continuation-passing-style for the writer output.

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.

The RWS monad

type RWS r w s = RWST r w s Identity

rws :: Monoid w => (r -> s -> (a, s, w)) -> RWS r w s a

runRWS :: Monoid w => RWS r w s a -> r -> s -> (a, s, w)

evalRWS :: Monoid w => RWS r w s a -> r -> s -> (a, w)

execRWS :: Monoid w => RWS r w s a -> r -> s -> (s, w)

mapRWS :: (Monoid w, Monoid w') => ((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

The RWST monad transformer

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

Instances

MonadTrans (RWST r w s)

Methods

lift :: Monad m => m a -> RWST r w s m a

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

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

Methods

mfix :: (a -> RWST r w s m a) -> RWST r w s m a

MonadFail m => MonadFail (RWST r w s m)

Methods

fail :: String -> RWST r w s m a

(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

(*>) :: 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

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

Methods

liftIO :: IO a -> RWST r w s m a

(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]

(Functor m, 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

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

evalRWST :: (Monad m, Monoid w) => RWST r w s m a -> r -> s -> m (a, w)

execRWST :: (Monad m, Monoid w) => RWST r w s m a -> r -> s -> m (s, w)

mapRWST :: (Monad n, Monoid w, Monoid w') => (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

Orphan instances

(Monoid w, Monad m) => MonadWriter w (RWST r w s m)

Methods

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

tell :: w -> RWST r w s m ()

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

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

Monad m => MonadState s (RWST r w s m)

Methods

get :: RWST r w s m s

put :: s -> RWST r w s m ()

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

Monad m => MonadReader r (RWST r w s m)

Methods

ask :: RWST r w s m r

local :: (r -> r) -> RWST r w s m a -> RWST r w s m a

reader :: (r -> a) -> RWST r w s m a