{-# LANGUAGE DeriveFunctor #-} {-# LANGUAGE ExistentialQuantification #-} {-# LANGUAGE StandaloneDeriving #-} module Control.Effect.Catch.Internal ( Catch(..) ) where import Control.Effect.Class -- | 'Catch' effects can be used alongside 'Control.Effect.Throw.Throw' to provide recoverable exceptions. -- -- @since 1.0.0.0 data Catch e m k = forall b . Catch (m b) (e -> m b) (b -> m k) deriving instance Functor m => Functor (Catch e m) instance HFunctor (Catch e) where hmap f (Catch m h k) = Catch (f m) (f . h) (f . k) instance Effect (Catch e) where thread ctx handler (Catch m h k) = Catch (handler (m <$ ctx)) (handler . (<$ ctx) . h) (handler . fmap k)