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We also recommend that a + file or class name and description of purpose be included on the + same "printed page" as the copyright notice for easier + identification within third-party archives. + + Copyright {yyyy} {name of copyright owner} + + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. diff --git a/Setup.hs b/Setup.hs new file mode 100644 --- /dev/null +++ b/Setup.hs @@ -0,0 +1,2 @@ +import Distribution.Simple +main = defaultMain diff --git a/errors-ext.cabal b/errors-ext.cabal new file mode 100644 --- /dev/null +++ b/errors-ext.cabal @@ -0,0 +1,40 @@ +name: errors-ext +version: 0.1 +synopsis: A bracket function for ExceptT over IO monad. +description: A bracket function for ExceptT over IO monad. +homepage: https://github.com/A1-Triard/errors-ext#readme +license: Apache +license-file: LICENSE +author: Warlock +maintainer: internalmike@gmail.com +copyright: 2017 Warlock +category: Web +build-type: Simple +-- extra-source-files: +cabal-version: >=1.10 + +library + hs-source-dirs: src + exposed-modules: Control.Error.Extensions + ghc-options: -fmax-pmcheck-iterations=100000000 -Wall -fprint-potential-instances + build-depends: base >= 4.7 && < 5 + , errors + , transformers + default-language: Haskell2010 + +test-suite errors-ext-test + type: exitcode-stdio-1.0 + hs-source-dirs: test + main-is: Spec.hs + other-modules: Control.Error.Extensions.Spec + ghc-options: -threaded -rtsopts -with-rtsopts=-N -fmax-pmcheck-iterations=100000000 -Wall -fprint-potential-instances + build-depends: base + , HUnit + , errors-ext + , errors + , transformers + default-language: Haskell2010 + +source-repository head + type: git + location: https://github.com/A1-Triard/errors-ext diff --git a/src/Control/Error/Extensions.hs b/src/Control/Error/Extensions.hs new file mode 100644 --- /dev/null +++ b/src/Control/Error/Extensions.hs @@ -0,0 +1,48 @@ +-- +-- Copyright 2017 Warlock +-- +-- Licensed under the Apache License, Version 2.0 (the "License"); +-- you may not use this file except in compliance with the License. +-- You may obtain a copy of the License at +-- +-- http://www.apache.org/licenses/LICENSE-2.0 +-- +-- Unless required by applicable law or agreed to in writing, software +-- distributed under the License is distributed on an "AS IS" BASIS, +-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +-- See the License for the specific language governing permissions and +-- limitations under the License. +-- + +module Control.Error.Extensions + ( bracketE + , bracketE_ + ) where + +import Control.Error.Util +import Control.Exception +import Control.Monad +import Control.Monad.Trans.Class +import Control.Monad.Trans.Except + +-- | Analogous to 'bracket', but for ExceptT over IO. +bracketE :: ExceptT e IO a -> (a -> ExceptT e IO b) -> (a -> ExceptT e IO c) -> ExceptT e IO c +bracketE acquire release action = (hoistEither =<<) $ lift $ do + resource <- runExceptT acquire + result <- bracketOnError (return resource) (handleAll . ioRelease) ioAction + if isLeft result + then handleAll (ioRelease resource) >> return result + else caseResult result <$> ioRelease resource + where + handleAll = handle (\x -> let _ = x :: SomeException in return ()) . void + ioAction (Left e) = return $ Left e + ioAction (Right r) = runExceptT $ action r + ioRelease (Left e) = return $ Left e + ioRelease (Right r) = runExceptT $ release r + caseResult (Left e) _ = Left e + caseResult (Right _) (Left e) = Left e + caseResult (Right r) (Right _) = Right r + +-- | A variant of 'bracketE' where the return value from the first computation is not required. +bracketE_ :: ExceptT e IO a -> ExceptT e IO b -> ExceptT e IO c -> ExceptT e IO c +bracketE_ acquire release action = bracketE acquire (const release) (const action) diff --git a/test/Control/Error/Extensions/Spec.hs b/test/Control/Error/Extensions/Spec.hs new file mode 100644 --- /dev/null +++ b/test/Control/Error/Extensions/Spec.hs @@ -0,0 +1,106 @@ +-- +-- Copyright 2017 Warlock +-- +-- Licensed under the Apache License, Version 2.0 (the "License"); +-- you may not use this file except in compliance with the License. +-- You may obtain a copy of the License at +-- +-- http://www.apache.org/licenses/LICENSE-2.0 +-- +-- Unless required by applicable law or agreed to in writing, software +-- distributed under the License is distributed on an "AS IS" BASIS, +-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +-- See the License for the specific language governing permissions and +-- limitations under the License. +-- + +module Control.Error.Extensions.Spec + ( tests + ) where + +import Test.HUnit.Base hiding (Label) +import Test.HUnit.Text +import Control.Error.Extensions +import Control.Exception +import Control.Monad.Trans.Class +import Control.Monad.Trans.Except +import Data.IORef +import System.IO.Error + +tests :: Test +tests = TestList $ (TestCase . runBracketTest) <$> bracketTests + +data Resource = Resource { acquired :: !Bool, released :: !Bool, processed :: !Bool } deriving (Eq, Show) + +resource :: IO (IORef Resource) +resource = newIORef $ Resource False False False + +type Acquire = IORef Resource -> ExceptT String IO (IORef Resource) + +acquireOk :: Acquire +acquireOk r = do + lift $ modifyIORef' r $ \x -> x { acquired = True } + return r + +acquireEx :: Acquire +acquireEx _ = lift $ fail "acquireEx" + +acquireEr :: Acquire +acquireEr _ = throwE "acquireEr" + +type Release = IORef Resource -> ExceptT String IO () + +releaseOk :: Release +releaseOk r = lift $ modifyIORef' r $ \x -> x { released = True } + +releaseEx :: Release +releaseEx _ = lift $ fail "releaseEx" + +releaseEr :: Release +releaseEr _ = throwE "releaseEr" + +type Process = IORef Resource -> ExceptT String IO Resource + +processOk :: Process +processOk r = lift $ do + v <- readIORef r + modifyIORef' r $ \x -> x { processed = True } + return v + +processEx :: Process +processEx _ = lift $ fail "processEx" + +processEr :: Process +processEr _ = throwE "processEr" + +data Error = Error { isException :: !Bool, message :: !String } deriving (Eq, Show) + +bracketTest :: Acquire -> Release -> Process -> IO (Resource, Either Error Resource) +bracketTest acquire release process = do + r <- resource + p <- catch (either (\x -> Left $ Error False x) Right <$> (runExceptT $ bracketE (acquire r) release process)) $ \e -> + let _ = e :: IOError in return $ Left $ Error True $ ioeGetErrorString e + f <- readIORef r + return (f, p) + +data TestData = TestData String !Acquire !Release !Process !(Resource, Either Error Resource) + +bracketTests :: [TestData] +bracketTests = + [ TestData "1" acquireOk releaseOk processOk (Resource True True True, Right $ Resource True False False) + , TestData "2" acquireEx releaseOk processOk (Resource False False False, Left $ Error { isException = True, message = "acquireEx" }) + , TestData "3" acquireEr releaseOk processOk (Resource False False False, Left $ Error { isException = False, message = "acquireEr" }) + , TestData "4" acquireOk releaseEx processOk (Resource True False True, Left $ Error { isException = True, message = "releaseEx" }) + , TestData "5" acquireOk releaseEr processOk (Resource True False True, Left $ Error { isException = False, message = "releaseEr" }) + , TestData "6" acquireOk releaseOk processEx (Resource True True False, Left $ Error { isException = True, message = "processEx" }) + , TestData "7" acquireOk releaseOk processEr (Resource True True False, Left $ Error { isException = False, message = "processEr" }) + , TestData "8" acquireOk releaseEx processEx (Resource True False False, Left $ Error { isException = True, message = "processEx" }) + , TestData "9" acquireOk releaseEr processEx (Resource True False False, Left $ Error { isException = True, message = "processEx" }) + , TestData "10" acquireOk releaseEx processEr (Resource True False False, Left $ Error { isException = False, message = "processEr" }) + , TestData "11" acquireOk releaseEr processEr (Resource True False False, Left $ Error { isException = False, message = "processEr" }) + ] + +runBracketTest :: TestData -> Assertion +runBracketTest (TestData m a r p e) = do + t <- bracketTest a r p + assertEqual m e t diff --git a/test/Spec.hs b/test/Spec.hs new file mode 100644 --- /dev/null +++ b/test/Spec.hs @@ -0,0 +1,28 @@ +-- +-- Copyright 2017 Warlock +-- +-- Licensed under the Apache License, Version 2.0 (the "License"); +-- you may not use this file except in compliance with the License. +-- You may obtain a copy of the License at +-- +-- http://www.apache.org/licenses/LICENSE-2.0 +-- +-- Unless required by applicable law or agreed to in writing, software +-- distributed under the License is distributed on an "AS IS" BASIS, +-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +-- See the License for the specific language governing permissions and +-- limitations under the License. +-- + +import Test.HUnit.Base hiding (Label) +import Test.HUnit.Text +import Control.Monad +import qualified Control.Error.Extensions.Spec + +main :: IO () +main = void $ runTestTT tests + +tests :: Test +tests = TestList + [ Control.Error.Extensions.Spec.tests + ]