asynchronous-exceptions (empty) → 1.0

raw patch · 4 files changed

+132/−0 lines, 4 filesdep +basesetup-changed

Dependencies added: base

Files

• Control/Exception/Async.hs +86/−0
• LICENSE +19/−0
• Setup.hs +2/−0
• asynchronous-exceptions.cabal +25/−0

@@ -0,0 +1,86 @@+{-# LANGUAGE DeriveDataTypeable, ExistentialQuantification #-}+-- |+-- It is often useful to distinguish between synchronous and asynchronous+-- exceptions. The common idiom is to run a user-supplied computation+-- catching any synchronous exceptions but allowing asynchronous exceptions+-- (such as user interrupt) pass through.+--+-- There's no way to know how — synchronously or asynchronously — an+-- exception was thrown, so we have to work around it by relying on the+-- exception type itself.+--+-- This module provides an extensible type for asynchronous exceptions+-- — 'SomeAsyncException' — as well as functions for catching synchronous+-- exceptions.++module Control.Exception.Async+  ( SomeAsyncException+  , asyncToException+  , asyncFromException+  , isAsynchronous+  , catchSync+  , handleSync+  , trySync+  )+  where++import Control.Exception as E+import Control.Monad+import Data.Typeable+import Data.Maybe++-- | Exception class for asynchronous exceptions.+--+-- To mark an exception as asynchronous:+--+-- >instance Exception MyException where+-- >  fromException = asyncFromException+-- >  toException = asyncToException+--+-- Note that as of base 4.6, 'AsyncException' is not yet a subclass of+-- 'SomeAsyncException'. Use 'isAsynchronous' to recognize both+-- 'AsyncException' and 'SomeAsyncException'.+data SomeAsyncException+  = forall e . Exception e => SomeAsyncException e+  deriving Typeable++instance Exception SomeAsyncException++instance Show SomeAsyncException where+  showsPrec p (SomeAsyncException e) = showsPrec p e++-- | 'toException' implementation for asynchronous exceptions+asyncToException :: Exception e => e -> SomeException+asyncToException = toException . SomeAsyncException++-- | 'fromException' implementation for asynchronous exceptions+asyncFromException :: Exception e => SomeException -> Maybe e+asyncFromException x = do+  SomeException e <- fromException x+  cast e++-- | Check whether an exception is asynchronous+isAsynchronous :: SomeException -> Bool+isAsynchronous e =+  isJust (fromException e :: Maybe AsyncException) ||+  isJust (fromException e :: Maybe SomeAsyncException)+++-- | Like 'catch', but catch any synchronous exceptions; let asynchronous ones pass through+catchSync :: IO a -> (SomeException -> IO a) -> IO a+catchSync a h =+  E.catch a $ \e ->+    if isAsynchronous e+      then throwIO e+      else h e++-- | Like 'handle', but catch any synchronous exceptions; let asynchronous ones pass through+handleSync :: (SomeException -> IO a) -> IO a -> IO a+handleSync = flip catchSync++-- | Like 'try', but catch any synchronous exceptions; let asynchronous ones pass through+trySync :: IO b -> IO (Either SomeException b)+trySync a =+  catchSync+    (liftM Right a)+    (return . Left)

@@ -0,0 +1,19 @@+Copyright (c) 2014 Roman Cheplyaka++Permission is hereby granted, free of charge, to any person obtaining a copy+of this software and associated documentation files (the "Software"), to deal+in the Software without restriction, including without limitation the rights+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell+copies of the Software, and to permit persons to whom the Software is+furnished to do so, subject to the following conditions:++The above copyright notice and this permission notice shall be included in+all copies or substantial portions of the Software.++THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN+THE SOFTWARE.

@@ -0,0 +1,2 @@+import Distribution.Simple+main = defaultMain

@@ -0,0 +1,25 @@+-- Initial asynchronous-exceptions.cabal generated by cabal init.  For+-- further documentation, see http://haskell.org/cabal/users-guide/++name:                asynchronous-exceptions+version:             1.0+synopsis:            Distinguish between synchronous and asynchronous exceptions+description:         Distinguish between synchronous and asynchronous exceptions+homepage:            https://github.com/feuerbach/asynchronous-exceptions+license:             MIT+license-file:        LICENSE+author:              Roman Cheplyaka+maintainer:          roma@ro-che.info+-- copyright:+category:            Control+build-type:          Simple+-- extra-source-files:+cabal-version:       >=1.10++library+  exposed-modules:     Control.Exception.Async+  -- other-modules:+  other-extensions:    DeriveDataTypeable, ExistentialQuantification+  build-depends:       base >=4.6 && <4.7+  -- hs-source-dirs:+  default-language:    Haskell2010