rio-0.1.8.0: A standard library for Haskell

Safe Haskell | Safe
Language | Haskell2010

RIO.State

Description

Provides reexports of `MonadState` and related helpers.

Since: 0.1.4.0

Synopsis

- class Monad m => MonadState s (m :: Type -> Type) | m -> s where
  - get :: m s
  - put :: s -> m ()
  - state :: (s -> (a, s)) -> m a
- gets :: MonadState s m => (s -> a) -> m a
- modify :: MonadState s m => (s -> s) -> m ()
- modify' :: MonadState s m => (s -> s) -> m ()

# Documentation

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

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

Minimal complete definition

state | get, put

Methods

get :: m s Source #

Return the state from the internals of the monad.

put :: s -> m () Source #

Replace the state inside the monad.

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

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 Source # put :: s -> RIO env () Source # state :: (s -> (a, s)) -> RIO env a Source #
MonadState s m => MonadState s (MaybeT m) |
Instance details Defined in Control.Monad.State.Class Methods get :: MaybeT m s Source # put :: s -> MaybeT m () Source # state :: (s -> (a, s)) -> MaybeT m a Source #
MonadState s m => MonadState s (ListT m) |
Instance details Defined in Control.Monad.State.Class Methods get :: ListT m s Source # put :: s -> ListT m () Source # state :: (s -> (a, s)) -> ListT m a Source #
(Monoid w, MonadState s m) => MonadState s (WriterT w m) |
Instance details Defined in Control.Monad.State.Class Methods get :: WriterT w m s Source # put :: s -> WriterT w m () Source # state :: (s -> (a, s)) -> WriterT w m a Source #
(Monoid w, MonadState s m) => MonadState s (WriterT w m) |
Instance details Defined in Control.Monad.State.Class Methods get :: WriterT w m s Source # put :: s -> WriterT w m () Source # state :: (s -> (a, s)) -> WriterT w m a Source #
Monad m => MonadState s (StateT s m) |
Instance details Defined in Control.Monad.State.Class Methods get :: StateT s m s Source # put :: s -> StateT s m () Source # state :: (s -> (a, s)) -> StateT s m a Source #
Monad m => MonadState s (StateT s m) |
Instance details Defined in Control.Monad.State.Class Methods get :: StateT s m s Source # put :: s -> StateT s m () Source # state :: (s -> (a, s)) -> StateT s m a Source #
MonadState s m => MonadState s (ReaderT r m) |
Instance details Defined in Control.Monad.State.Class Methods get :: ReaderT r m s Source # put :: s -> ReaderT r m () Source # state :: (s -> (a, s)) -> ReaderT r m a Source #
MonadState s m => MonadState s (IdentityT m) |
Instance details Defined in Control.Monad.State.Class Methods get :: IdentityT m s Source # put :: s -> IdentityT m () Source # state :: (s -> (a, s)) -> IdentityT m a Source #
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 Source # put :: s -> ExceptT e m () Source # state :: (s -> (a, s)) -> ExceptT e m a Source #
(Error e, MonadState s m) => MonadState s (ErrorT e m) |
Instance details Defined in Control.Monad.State.Class Methods get :: ErrorT e m s Source # put :: s -> ErrorT e m () Source # state :: (s -> (a, s)) -> ErrorT e m a Source #
MonadState s m => MonadState s (ContT r m) |
Instance details Defined in Control.Monad.State.Class Methods get :: ContT r m s Source # put :: s -> ContT r m () Source # state :: (s -> (a, s)) -> ContT r m a Source #
(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 Source # put :: s -> RWST r w s m () Source # state :: (s -> (a, s)) -> RWST r w s m a Source #
(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 Source # put :: s -> RWST r w s m () Source # state :: (s -> (a, s)) -> RWST r w s m a Source #

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

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

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

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 () Source #

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

Since: mtl-2.2