Control.Effects.Writer

Documentation

data Writer m a

The functor representing the effect. You shouldn't need to create this manually, just use tell

Constructors

Writer m a

Instances

Functor (Writer m)

Methods

fmap :: (a -> b) -> Writer m a -> Writer m b

(<$) :: a -> Writer m b -> Writer m a

tell :: (Member (Writer m) r, Typeable m) => m -> Eff r ()

Send a value into the writer

writerHandler :: Monoid m => Handler (Writer m) r a (a, m)

Handles writes by mappending them together.