failure-0.1.1: A simple type class for success/failure computations.

Control.Failure

Contents

Description

Type classes for returning failures.

Synopsis

Type class

class Monad f => Failure e f whereSource

Methods

failure :: e -> f vSource

Instances

Exception e => Failure e IO 
Failure e [] 
Failure e Maybe 
(MonadTrans t, Failure e m, Monad (t m)) => Failure e (t m)

Instance for all monad transformers, simply lift the failure into the base monad.

Failure e (Either e) 

Wrapping failures

class Failure e f => WrapFailure e f whereSource

Methods

wrapFailure :: (forall eIn. Exception eIn => eIn -> e) -> f a -> f aSource

Wrap the failure value, if any, with the given function. This is useful in particular when you want all the exceptions returned from a certain library to be of a certain type, even if they were generated by a different library.

Instances

Convenience String failure

Convert Failures into concrete types

class Try f whereSource

Associated Types

type Error f Source

Methods

try :: Failure (Error f) f' => f a -> f' aSource

Instances

Try [] 
Try Maybe 
Try (Either e)