Control.Monad.State.Persistent

Documentation

data PersistentStateT s m a

A State monad that can store earlier versions of the state.

Instances

Monad m => MonadState s (PersistentStateT s m)

Defined in Control.Monad.State.Persistent

Methods

get :: PersistentStateT s m s

put :: s -> PersistentStateT s m ()

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

Monad m => Monad (PersistentStateT s m)

Defined in Control.Monad.State.Persistent

Methods

(>>=) :: PersistentStateT s m a -> (a -> PersistentStateT s m b) -> PersistentStateT s m b

(>>) :: PersistentStateT s m a -> PersistentStateT s m b -> PersistentStateT s m b

return :: a -> PersistentStateT s m a

fail :: String -> PersistentStateT s m a

Functor m => Functor (PersistentStateT s m)

Defined in Control.Monad.State.Persistent

Methods

fmap :: (a -> b) -> PersistentStateT s m a -> PersistentStateT s m b

(<$) :: a -> PersistentStateT s m b -> PersistentStateT s m a

Monad m => Applicative (PersistentStateT s m)

Defined in Control.Monad.State.Persistent

Methods

pure :: a -> PersistentStateT s m a

(<*>) :: PersistentStateT s m (a -> b) -> PersistentStateT s m a -> PersistentStateT s m b

liftA2 :: (a -> b -> c) -> PersistentStateT s m a -> PersistentStateT s m b -> PersistentStateT s m c

(*>) :: PersistentStateT s m a -> PersistentStateT s m b -> PersistentStateT s m b

(<*) :: PersistentStateT s m a -> PersistentStateT s m b -> PersistentStateT s m a

type PersistentState s = PersistentStateT s Identity

store :: Monad m => PersistentStateT s m ()

Create a snapshot of the current state and add it to the list of states that we store.

runPersistentStateT :: Functor m => PersistentStateT s m a -> s -> m (a, s, [s])

run a persistentStateT, returns a triplet with the value, the last state and a list of all states (including the last one) in chronological order

runPersistentState :: PersistentState s a -> s -> (a, s, [s])