Module

Control.Error.Util

Use these functions to convert between Maybe, Either, MaybeT, and ExceptT.

hush :: forall b a. Either a b -> Maybe b

Suppress the Left value of an Either

hushT :: forall m b a. Monad m => ExceptT a m b -> MaybeT m b

Suppress the Left value of an ExceptT

note :: forall b a. a -> Maybe b -> Either a b

Tag the Nothing value of a Maybe

noteT :: forall m b a. Monad m => a -> MaybeT m b -> ExceptT a m b

Tag the Nothing value of a MaybeT

hoistMaybe :: forall m b. Monad m => Maybe b -> MaybeT m b

Lift a Maybe to the MaybeT monad

exceptNoteM :: forall m e a. Applicative m => Maybe a -> e -> ExceptT e m a

Convert a Maybe value into the ExceptT monad

Operator alias for Control.Error.Util.exceptNoteM (left-associative / precedence 9)

exceptNoteA :: forall m e a. Apply m => m (Maybe a) -> e -> ExceptT e m a

Convert an applicative Maybe value into the ExceptT monad

Operator alias for Control.Error.Util.exceptNoteA (left-associative / precedence 9)

bool :: forall a. a -> a -> Boolean -> a

Case analysis for the Boolean type

fromMaybe' :: forall a. Maybe a -> a -> a

An infix form of fromMaybe with arguments flipped.

Operator alias for Control.Error.Util.fromMaybe' (left-associative / precedence 9)