| Copyright | (c) Edward Kmett & Sjoerd Visscher 2011 |
|---|---|
| License | BSD3 |
| Maintainer | ekmett@gmail.com |
| Stability | experimental |
| Safe Haskell | Safe-Inferred |
| Language | Haskell2010 |
Control.Monad.Representable.State
Description
A generalized State monad, parameterized by a Representable functor. The representation of that functor serves as the state.
Synopsis
- type State g = StateT g Identity
- runState :: Representable g => State g a -> Rep g -> (a, Rep g)
- evalState :: Representable g => State g a -> Rep g -> a
- execState :: Representable g => State g a -> Rep g -> Rep g
- mapState :: Functor g => ((a, Rep g) -> (b, Rep g)) -> State g a -> State g b
- newtype StateT g m a = StateT { }
- stateT :: Representable g => ( Rep g -> m (a, Rep g)) -> StateT g m a
- runStateT :: Representable g => StateT g m a -> Rep g -> m (a, Rep g)
- evalStateT :: ( Representable g, Monad m) => StateT g m a -> Rep g -> m a
- execStateT :: ( Representable g, Monad m) => StateT g m a -> Rep g -> m ( Rep g)
- mapStateT :: Functor g => (m (a, Rep g) -> n (b, Rep g)) -> StateT g m a -> StateT g n b
- liftCallCC :: Representable g => ((((a, Rep g) -> m (b, Rep g)) -> m (a, Rep g)) -> m (a, Rep g)) -> ((a -> StateT g m b) -> StateT g m a) -> StateT g m a
- liftCallCC' :: Representable g => ((((a, Rep g) -> m (b, Rep g)) -> m (a, Rep g)) -> m (a, Rep g)) -> ((a -> StateT g m b) -> StateT g m a) -> StateT g m a
- class Monad m => MonadState s (m :: Type -> Type ) | m -> s where
Documentation
type State g = StateT g Identity Source #
A memoized state monad parameterized by a representable functor
g
, where
the representatation of
g
,
Rep g
is 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.
Arguments
| :: Representable g | |
| => State g a |
state-passing computation to execute |
| -> Rep g |
initial state |
| -> (a, Rep g) |
return value and final state |
Unwrap a state monad computation as a function.
(The inverse of
state
.)
Arguments
| :: Representable g | |
| => State g a |
state-passing computation to execute |
| -> Rep g |
initial value |
| -> a |
return value of the state computation |
Arguments
| :: Representable g | |
| => State g a |
state-passing computation to execute |
| -> Rep g |
initial value |
| -> Rep g |
final state |
A state transformer monad parameterized by:
-
g- A representable functor used to memoize results for a stateRep g -
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.
Instances
evalStateT :: ( Representable g, Monad m) => StateT g m a -> Rep g -> m a Source #
Evaluate a state computation with the given initial state and return the final value, discarding the final state.
-
evalStateTm s =liftMfst(runStateTm s)
execStateT :: ( Representable g, Monad m) => StateT g m a -> Rep g -> m ( Rep g) Source #
Evaluate a state computation with the given initial state and return the final state, discarding the final value.
-
execStateTm s =liftMsnd(runStateTm s)
liftCallCC :: Representable g => ((((a, Rep g) -> m (b, Rep g)) -> m (a, Rep g)) -> m (a, Rep g)) -> ((a -> StateT g m b) -> StateT g m a) -> StateT g m a Source #
Uniform lifting of a
callCC
operation to the new monad.
This version rolls back to the original state on entering the
continuation.
liftCallCC' :: Representable g => ((((a, Rep g) -> m (b, Rep g)) -> m (a, Rep g)) -> m (a, Rep g)) -> ((a -> StateT g m b) -> StateT g m a) -> StateT g m a Source #
In-situ lifting of a
callCC
operation to the new monad.
This version uses the current state on entering the continuation.
It does not satisfy the laws of a monad transformer.
class Monad m => MonadState s (m :: Type -> Type ) | m -> s where Source #
Minimal definition is either both of
get
and
put
or just
state
Methods
Return the state from the internals of the monad.
Replace the state inside the monad.
state :: (s -> (a, s)) -> m a Source #
Embed a simple state action into the monad.
Instances
| MonadState s m => MonadState s ( MaybeT m) | |
| MonadState s m => MonadState s ( ListT m) | |
| ( Functor m, MonadState s m) => MonadState s ( Free m) | |
| ( Representable g, Monad m, Rep g ~ s) => MonadState s ( StateT g m) Source # | |
| ( Monoid w, MonadState s m) => MonadState s ( WriterT w m) | |
| ( Monoid w, MonadState s m) => MonadState s ( WriterT w m) | |
| Monad m => MonadState s ( StateT s m) | |
| Monad m => MonadState s ( StateT s m) | |
| MonadState s m => MonadState s ( ReaderT r m) | |
| MonadState s m => MonadState s ( IdentityT m) | |
| MonadState s m => MonadState s ( ExceptT e m) |
Since: mtl-2.2 |
| ( Error e, MonadState s m) => MonadState s ( ErrorT e m) | |
| ( Functor f, MonadState s m) => MonadState s ( FreeT f m) | |
| MonadState s m => MonadState s ( ContT r m) | |
| ( Monad m, Monoid w) => MonadState s ( RWST r w s m) | |
| ( Monad m, Monoid w) => MonadState s ( RWST r w s m) | |