Control.Monad.Attempt

attempt-0.0.0: Error handling using extensible exceptions outside the IO monad.

Control.Monad.Attempt

Description

Provide a monad transformer for the attempt monad, which allows the reporting of errors using extensible exceptions.

Synopsis

newtype AttemptT m v = AttemptT {

runAttemptT :: m (Attempt v)

}

evalAttemptT :: (Monad m, FromAttempt m) => AttemptT m v -> m v

module Data.Attempt

Documentation

newtype AttemptT m v

Constructors

AttemptT

runAttemptT :: m (Attempt v)

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Instances

MonadTrans AttemptT

Monad m => Monad (AttemptT m)

Monad m => Functor (AttemptT m)

Monad m => Applicative (AttemptT m)

MonadIO m => MonadIO (AttemptT m)

Monad m => MonadAttempt (AttemptT m)

Monad m => FromAttempt (AttemptT m)

evalAttemptT :: (Monad m, FromAttempt m) => AttemptT m v -> m v

Instances of FromAttempt specify a manner for embedding Attempt failures directly into the target data type. For example, the IO instance simply throws a runtime error. This is a convenience wrapper when you simply want to use that default action.

So given a type AttemptT IO Int, this function will convert it to IO Int, throwing any exceptions in the original value.

module Data.Attempt

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