Effectful.Class.Writer

Documentation

class Monad m => MonadWriter w m where

Compatiblity layer for a transition period from MTL-style effect handling to Eff.

Minimal complete definition

(writer | tell), listen

Methods

writer :: (a, w) -> m a

tell :: w -> m ()

listen :: m a -> m (a, w)

Instances

(Writer w :> es, Monoid w) => MonadWriter w (Eff es)

Defined in Effectful.Class.Writer

Methods

writer :: (a, w) -> Eff es a

tell :: w -> Eff es ()

listen :: Eff es a -> Eff es (a, w)

(MonadWriter w m, MonadTransControl t, Monad (t m)) => MonadWriter w (t m)

Generic, overlappable instance.

Defined in Effectful.Class.Writer

Methods

writer :: (a, w) -> t m a

tell :: w -> t m ()

listen :: t m a -> t m (a, w)

listens :: MonadWriter w m => (w -> b) -> m a -> m (a, b)