failure-0.1.0.1: A simple type class for success/failure computations. Contents Index

Control.Failure

Contents Type class Wrapping failures Convenience String failure Convert Failures into concrete types

Description

Type classes for returning failures.

Synopsis

class Monad f => Failure e f where failure :: e -> f v class Failure e f => WrapFailure e f where wrapFailure :: (forall eIn. Exception eIn => eIn -> e) -> f a -> f a newtype StringException = StringException String failureString :: Failure StringException m => String -> m a class Try f where type Error f try :: Failure (Error f) f' => f a -> f' a data NothingException = NothingException data NullException = NullException

Type class

class Monad f => Failure e f where

Methods failure :: e -> f v Instances Exception e => Failure e IO Failure e [] Failure e Maybe

Wrapping failures

class Failure e f => WrapFailure e f where

Methods wrapFailure :: (forall eIn. Exception eIn => eIn -> e) -> f a -> f a 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 Exception e => WrapFailure e IO

Convenience String failure

newtype StringException

Constructors StringException String Instances Show StringException Typeable StringException Exception StringException

failureString :: Failure StringException m => String -> m a

Call failure with a String.

Convert Failures into concrete types

class Try f where

Associated Types type Error f Methods try :: Failure (Error f) f' => f a -> f' a Instances Try [] Try Maybe Try (Either e)

data NothingException

Constructors NothingException Instances Show NothingException Typeable NothingException Exception NothingException

data NullException

Constructors NullException Instances Show NullException Typeable NullException Exception NullException

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