runState -package:ghc-lib-parser -package:cleff

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

Run a State effect with local state.

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

Encapsulation of a state-using computation, exposing the initial and final states. Typical usage in arrow notation:

proc p -> do
...
(result, final_state) <- (|runState cmd|) init_state

Run a State effect starting from the passed value, applying a continuation to the final state and result.

runState k s (pure a) = k s a

runState k s get = k s s

runState k s (put t) = k t ()

Run a State effect starting from the passed value.

runState s (pure a) = pure (s, a)

runState s get = pure (s, s)

runState s (put t) = pure (t, ())

Run a lazy State effect, yielding the result value and the final state. More programs terminate with lazy state than strict state, but injudicious use of lazy state may lead to thunk buildup.

runState s (pure a) = pure (s, a)

runState s get = pure (s, s)

runState s (put t) = pure (t, ())

Run a State effect starting from the passed value.

runState s (pure a) = pure (s, a)

runState s get = pure (s, s)

runState s (put t) = pure (t, ())

Run the State effect with the given initial state and return the final value along with the final state.

Run a State effect

Run a State effect

Run a State effect with local state.

This is the state record that controls the output style.

Runs a monadic generating action in the State monad using a pure pseudo-random number generator.

Examples

>>> import System.Random.Stateful

>>> let pureGen = mkStdGen 137

>>> runStateGen pureGen randomM :: (Int, StdGen)
(7879794327570578227,StdGen {unStdGen = SMGen 11285859549637045894 7641485672361121627})

Runs a monadic generating action in the ST monad using a pure pseudo-random number generator.

Runs a monadic generating action in the ST monad using a pure pseudo-random number generator. Same as runStateGenST, but discards the resulting generator.

Runs a monadic generating action in the StateT monad using a pure pseudo-random number generator.

Examples

>>> import System.Random.Stateful

>>> let pureGen = mkStdGen 137

>>> runStateGenT pureGen randomM :: IO (Int, StdGen)
(7879794327570578227,StdGen {unStdGen = SMGen 11285859549637045894 7641485672361121627})

Runs a monadic generating action in the StateT monad using a pure pseudo-random number generator. Returns only the resulting pseudo-random value.

Examples

>>> import System.Random.Stateful

>>> let pureGen = mkStdGen 137

>>> runStateGenT_ pureGen randomM :: IO Int
7879794327570578227