effect-handlers-0.1.0.8: A library for writing extensible algebraic effects and handlers. Similar to extensible-effects but with deep handlers.
Control.Effects.Writer
Synopsis
data Writer m a Source #
The functor representing the effect. You shouldn't need to create this manually, just use tell
tell
Constructors
Instances
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 () Source #
Send a value into the writer
writerHandler :: Monoid m => Handler (Writer m) r a (a, m) Source #
Handles writes by mappending them together.
mappend