Modulepolysemy-zoo-0.8.2.0Haskell2010

Polysemy.RevState

Contents

Synopsis

Effect

newtypenewtype RevState s (m :: k) a where

A State effect for threading state backwards instead of forwards through a computation.

valuerevState :: Member (RevState s) r => (s -> (s, a)) -> Sem r a

Gets the state as sent from the next call to revState / revPut / revModify, use it, and send a new state into the past.

valuerevGet :: Member (RevState s) r => Sem r s

Gets the state as sent from the next call to revState / revPut / revModify.

valuerevPut :: Member (RevState s) r => s -> Sem r ()

Sends a new state into the past.

valuerevModify :: Member (RevState s) r => (s -> s) -> Sem r ()

Gets the state as sent from the next call to revState / revModify / revPut, modify it, and return it into the past.

valuerunRevState

Run a RevState effect with local state that is propagated backwards through the computation, from last action to first.

valuerunLazyRevState

Run a RevState effect with local state that is lazily propagated backwards through the computation, from last action to first.