Effectful.Writer

The Writer as an effect.

Documentation

data Writer w

Provide access to a write only value of type w.

Instances

Semigroup w => Semigroup (Writer w)

Defined in Effectful.Writer

Methods

(<>) :: Writer w -> Writer w -> Writer w

sconcat :: NonEmpty (Writer w) -> Writer w

stimes :: Integral b => b -> Writer w -> Writer w

Monoid w => Monoid (Writer w)

Defined in Effectful.Writer

Methods

mempty :: Writer w

mappend :: Writer w -> Writer w -> Writer w

mconcat :: [Writer w] -> Writer w

runWriter :: Monoid w => Eff (Writer w ': es) a -> Eff es (a, w)

execWriter :: Monoid w => Eff (Writer w ': es) a -> Eff es w

writer :: (Writer w :> es, Monoid w) => (a, w) -> Eff es a

tell :: (Writer w :> es, Monoid w) => w -> Eff es ()

listen :: (Writer w :> es, Monoid w) => Eff es a -> Eff es (a, w)

listens :: (Writer w :> es, Monoid w) => (w -> b) -> Eff es a -> Eff es (a, b)