Copyright	(c) 2009 - 2014 Peter Trsko.
License	BSD3
Stability	provisional
Portability	non-portable (NoImplicitPrelude, RankNTypes)
Safe Haskell	Safe-Inferred
Language	Haskell2010

Control.Monad.TaggedException.Utilities

Description

Introduces MonadExceptionUtilities type class that provides means for overriding default implementation of functions like bracket.

Synopsis

Documentation

bracket Source

Arguments

:: (Exception e, MonadMask m)
=> m a	Computation to run before
-> (a -> m b)	Computation to run after
-> (a -> Throws e m c)	Computation to run in-between
-> Throws e m c	Result of the in-between computation

Run computation surrounded by acquire and release computations. The release computation is executed even if "in-between" computation raises exception. See also bracket', bracket_, bracketOnError, and bracketOnError'.

bracket' Source

Arguments

:: MonadMask m
=> m a	Computation to run before
-> (a -> m b)	Computation to run after
-> (a -> m c)	Computation to run in-between
-> m c	Result of the in-between computation

Run computation surrounded by acquire and release computations. The release computation is executed even if "in-between" computation raises exception. See also bracket, bracket_, bracketOnError, and bracketOnError'.

Default implementation:

bracket' acq rel go = mask' $ \ restore -> do
    x <- acq
    r <- restore (go x) `onException'` rel x
    _ <- rel x
    return r

bracket_ Source

Arguments

:: (Exception e, MonadMask m)
=> m a	Computation to run before
-> m b	Computation to run after
-> Throws e m c	Computation to run in-between
-> Throws e m c	Result of the in-between computation

Variant of bracket.

bracket_ acq rel go = bracket acq (const rel) (const go)

bracketOnError Source

Arguments

:: (Exception e, MonadMask m)
=> m a	Computation to run before
-> (a -> m b)	Computation to run after if an exception was raised
-> (a -> Throws e m c)	Computation to run in-between
-> Throws e m c	Result of the in-between computation

Version of bracket where "after" computation is executed only if "in-between" computation raises exception.

Default implementation:

bracketOnError acq rel go = mask $ \ restore -> do
    x <- liftT acq
    restore (go x) `onException` rel x

bracketOnError' Source

Arguments

:: MonadMask m
=> m a	Computation to run before
-> (a -> m b)	Computation to run after if an exception was raised
-> (a -> m c)	Computation to run in-between
-> m c	Result of the in-between computation

Version of bracket where "after" computation is executed only if "in-between" computation raises exception.

Default implementation:

bracketOnError' acq rel go = mask' $ \ restore -> do
    x <- liftT acq
    restore (go x) `onException'` rel x

finally Source

Arguments

:: (Exception e, MonadMask m)
=> Throws e m a	Computation to run first
-> m b	Computation to run afterward (even if exception `e` was raised)
-> Throws e m a	Returns the result of the first computation

Run computation afeter another even if exception was thrown. See also finally', onException and onException'.

Default implementation:

m `finally` n = mask $ \ restore -> do
    r <- restore m `onException` n
    _ <- liftT n
    return r

finally' Source

Arguments

:: MonadMask m
=> m a	Computation to run first
-> m b	Computation to run afterward (even if some exception was raised)
-> m a	Returns the result of the first computation

Run computation afeter another even if exception was thrown. See also finally, onException and onException'.