Effectful.State

The State as an effect.

Represented as a pure value underneath, therefore:

• very fast
• not suitable for sharing between multiple threads.

If you plan to do the latter, have a look at Effective.State.MVar or Effective.State.Dynamic.

Documentation

data State s

Provide access to a pure, mutable state of type s.

runState :: s -> Eff (State s ': es) a -> Eff es (a, s)

evalState :: s -> Eff (State s ': es) a -> Eff es a

execState :: s -> Eff (State s ': es) a -> Eff es s

get :: State s :> es => Eff es s

put :: State s :> es => s -> Eff es ()

state :: State s :> es => (s -> (a, s)) -> Eff es a

modify :: State s :> es => (s -> s) -> Eff es ()

stateM :: State s :> es => (s -> Eff es (a, s)) -> Eff es a

modifyM :: State s :> es => (s -> Eff es s) -> Eff es ()