rio-0.1.9.1: A standard library for Haskell

Safe HaskellSafe
LanguageHaskell2010

RIO.State

Description

Provides reexports of MonadState and related helpers.

Since: 0.1.4.0

Synopsis

Documentation

class Monad m => MonadState s (m :: Type -> Type) | m -> s where #

Minimal definition is either both of get and put or just state

Minimal complete definition

state | get, put

Methods

get :: m s #

Return the state from the internals of the monad.

put :: s -> m () #

Replace the state inside the monad.

state :: (s -> (a, s)) -> m a #

Embed a simple state action into the monad.

Instances
HasStateRef s env => MonadState s (RIO env) Source # 
Instance details

Defined in RIO.Prelude.RIO

Methods

get :: RIO env s #

put :: s -> RIO env () #

state :: (s -> (a, s)) -> RIO env a #

MonadState s m => MonadState s (MaybeT m) 
Instance details

Defined in Control.Monad.State.Class

Methods

get :: MaybeT m s #

put :: s -> MaybeT m () #

state :: (s -> (a, s)) -> MaybeT m a #

MonadState s m => MonadState s (ListT m) 
Instance details

Defined in Control.Monad.State.Class

Methods

get :: ListT m s #

put :: s -> ListT m () #

state :: (s -> (a, s)) -> ListT m a #

(Monoid w, MonadState s m) => MonadState s (WriterT w m) 
Instance details

Defined in Control.Monad.State.Class

Methods

get :: WriterT w m s #

put :: s -> WriterT w m () #

state :: (s -> (a, s)) -> WriterT w m a #

(Monoid w, MonadState s m) => MonadState s (WriterT w m) 
Instance details

Defined in Control.Monad.State.Class

Methods

get :: WriterT w m s #

put :: s -> WriterT w m () #

state :: (s -> (a, s)) -> WriterT w m a #

Monad m => MonadState s (StateT s m) 
Instance details

Defined in Control.Monad.State.Class

Methods

get :: StateT s m s #

put :: s -> StateT s m () #

state :: (s -> (a, s)) -> StateT s m a #

Monad m => MonadState s (StateT s m) 
Instance details

Defined in Control.Monad.State.Class

Methods

get :: StateT s m s #

put :: s -> StateT s m () #

state :: (s -> (a, s)) -> StateT s m a #

MonadState s m => MonadState s (IdentityT m) 
Instance details

Defined in Control.Monad.State.Class

Methods

get :: IdentityT m s #

put :: s -> IdentityT m () #

state :: (s -> (a, s)) -> IdentityT m a #

MonadState s m => MonadState s (ExceptT e m)

Since: mtl-2.2

Instance details

Defined in Control.Monad.State.Class

Methods

get :: ExceptT e m s #

put :: s -> ExceptT e m () #

state :: (s -> (a, s)) -> ExceptT e m a #

(Error e, MonadState s m) => MonadState s (ErrorT e m) 
Instance details

Defined in Control.Monad.State.Class

Methods

get :: ErrorT e m s #

put :: s -> ErrorT e m () #

state :: (s -> (a, s)) -> ErrorT e m a #

MonadState s m => MonadState s (ReaderT r m) 
Instance details

Defined in Control.Monad.State.Class

Methods

get :: ReaderT r m s #

put :: s -> ReaderT r m () #

state :: (s -> (a, s)) -> ReaderT r m a #

MonadState s m => MonadState s (ContT r m) 
Instance details

Defined in Control.Monad.State.Class

Methods

get :: ContT r m s #

put :: s -> ContT r m () #

state :: (s -> (a, s)) -> ContT r m a #

(Monad m, Monoid w) => MonadState s (RWST r w s m) 
Instance details

Defined in Control.Monad.State.Class

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, Monoid w) => MonadState s (RWST r w s m) 
Instance details

Defined in Control.Monad.State.Class

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 #

gets :: MonadState s m => (s -> a) -> m a #

Gets specific component of the state, using a projection function supplied.

modify :: MonadState s m => (s -> s) -> m () #

Monadic state transformer.

Maps an old state to a new state inside a state monad. The old state is thrown away.

     Main> :t modify ((+1) :: Int -> Int)
     modify (...) :: (MonadState Int a) => a ()

This says that modify (+1) acts over any Monad that is a member of the MonadState class, with an Int state.

modify' :: MonadState s m => (s -> s) -> m () #

A variant of modify in which the computation is strict in the new state.

Since: mtl-2.2

type State s = StateT s Identity #

A state monad parameterized by the type s of the state to carry.

The return function leaves the state unchanged, while >>= uses the final state of the first computation as the initial state of the second.

runState #

Arguments

:: State s a

state-passing computation to execute

-> s

initial state

-> (a, s)

return value and final state

Unwrap a state monad computation as a function. (The inverse of state.)

evalState #

Arguments

:: State s a

state-passing computation to execute

-> s

initial value

-> a

return value of the state computation

Evaluate a state computation with the given initial state and return the final value, discarding the final state.

execState #

Arguments

:: State s a

state-passing computation to execute

-> s

initial value

-> s

final state

Evaluate a state computation with the given initial state and return the final state, discarding the final value.

mapState :: ((a, s) -> (b, s)) -> State s a -> State s b #

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

withState :: (s -> s) -> State s a -> State s a #

withState f m executes action m on a state modified by applying f.

newtype StateT s (m :: Type -> Type) a #

A state transformer monad parameterized by:

  • s - The state.
  • m - The inner monad.

The return function leaves the state unchanged, while >>= uses the final state of the first computation as the initial state of the second.

Constructors

StateT 

Fields

Instances
MonadWriter w m => MonadWriter w (StateT s m) 
Instance details

Defined in Control.Monad.Writer.Class

Methods

writer :: (a, w) -> StateT s m a #

tell :: w -> StateT s m () #

listen :: StateT s m a -> StateT s m (a, w) #

pass :: StateT s m (a, w -> w) -> StateT s m a #

Monad m => MonadState s (StateT s m) 
Instance details

Defined in Control.Monad.State.Class

Methods

get :: StateT s m s #

put :: s -> StateT s m () #

state :: (s -> (a, s)) -> StateT s m a #

MonadReader r m => MonadReader r (StateT s m) 
Instance details

Defined in Control.Monad.Reader.Class

Methods

ask :: StateT s m r #

local :: (r -> r) -> StateT s m a -> StateT s m a #

reader :: (r -> a) -> StateT s m a #

MonadTrans (StateT s) 
Instance details

Defined in Control.Monad.Trans.State.Lazy

Methods

lift :: Monad m => m a -> StateT s m a #

Monad m => Monad (StateT s m) 
Instance details

Defined in Control.Monad.Trans.State.Lazy

Methods

(>>=) :: StateT s m a -> (a -> StateT s m b) -> StateT s m b #

(>>) :: StateT s m a -> StateT s m b -> StateT s m b #

return :: a -> StateT s m a #

fail :: String -> StateT s m a #

Functor m => Functor (StateT s m) 
Instance details

Defined in Control.Monad.Trans.State.Lazy

Methods

fmap :: (a -> b) -> StateT s m a -> StateT s m b #

(<$) :: a -> StateT s m b -> StateT s m a #

MonadFix m => MonadFix (StateT s m) 
Instance details

Defined in Control.Monad.Trans.State.Lazy

Methods

mfix :: (a -> StateT s m a) -> StateT s m a #

MonadFail m => MonadFail (StateT s m) 
Instance details

Defined in Control.Monad.Trans.State.Lazy

Methods

fail :: String -> StateT s m a #

(Functor m, Monad m) => Applicative (StateT s m) 
Instance details

Defined in Control.Monad.Trans.State.Lazy

Methods

pure :: a -> StateT s m a #

(<*>) :: StateT s m (a -> b) -> StateT s m a -> StateT s m b #

liftA2 :: (a -> b -> c) -> StateT s m a -> StateT s m b -> StateT s m c #

(*>) :: StateT s m a -> StateT s m b -> StateT s m b #

(<*) :: StateT s m a -> StateT s m b -> StateT s m a #

Contravariant m => Contravariant (StateT s m) 
Instance details

Defined in Control.Monad.Trans.State.Lazy

Methods

contramap :: (a -> b) -> StateT s m b -> StateT s m a #

(>$) :: b -> StateT s m b -> StateT s m a #

MonadIO m => MonadIO (StateT s m) 
Instance details

Defined in Control.Monad.Trans.State.Lazy

Methods

liftIO :: IO a -> StateT s m a #

(Functor m, MonadPlus m) => Alternative (StateT s m) 
Instance details

Defined in Control.Monad.Trans.State.Lazy

Methods

empty :: StateT s m a #

(<|>) :: StateT s m a -> StateT s m a -> StateT s m a #

some :: StateT s m a -> StateT s m [a] #

many :: StateT s m a -> StateT s m [a] #

MonadPlus m => MonadPlus (StateT s m) 
Instance details

Defined in Control.Monad.Trans.State.Lazy

Methods

mzero :: StateT s m a #

mplus :: StateT s m a -> StateT s m a -> StateT s m a #

MonadThrow m => MonadThrow (StateT s m) 
Instance details

Defined in Control.Monad.Catch

Methods

throwM :: Exception e => e -> StateT s m a #

MonadCatch m => MonadCatch (StateT s m) 
Instance details

Defined in Control.Monad.Catch

Methods

catch :: Exception e => StateT s m a -> (e -> StateT s m a) -> StateT s m a #

MonadMask m => MonadMask (StateT s m) 
Instance details

Defined in Control.Monad.Catch

Methods

mask :: ((forall a. StateT s m a -> StateT s m a) -> StateT s m b) -> StateT s m b #

uninterruptibleMask :: ((forall a. StateT s m a -> StateT s m a) -> StateT s m b) -> StateT s m b #

generalBracket :: StateT s m a -> (a -> ExitCase b -> StateT s m c) -> (a -> StateT s m b) -> StateT s m (b, c) #

PrimMonad m => PrimMonad (StateT s m) 
Instance details

Defined in Control.Monad.Primitive

Associated Types

type PrimState (StateT s m) :: Type #

Methods

primitive :: (State# (PrimState (StateT s m)) -> (#State# (PrimState (StateT s m)), a#)) -> StateT s m a #

type PrimState (StateT s m) 
Instance details

Defined in Control.Monad.Primitive

type PrimState (StateT s m) = PrimState m

evalStateT :: Monad m => StateT s m a -> s -> m a #

Evaluate a state computation with the given initial state and return the final value, discarding the final state.

execStateT :: Monad m => StateT s m a -> s -> m s #

Evaluate a state computation with the given initial state and return the final state, discarding the final value.

mapStateT :: (m (a, s) -> n (b, s)) -> StateT s m a -> StateT s n b #

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

withStateT :: (s -> s) -> StateT s m a -> StateT s m a #

withStateT f m executes action m on a state modified by applying f.