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bracket :: IO a -> (a -> IO b) -> (a -> IO c) -> IO cbase Control.Exception When you want to acquire a resource, do some work with it, and then release the resource, it is a good idea to use bracket, because bracket will install the necessary exception handler to release the resource in the event that an exception is raised during the computation. If an exception is raised, then bracket will re-raise the exception (after performing the release). A common example is opening a file:
bracket (openFile "filename" ReadMode) (hClose) (\fileHandle -> do { ... })
The arguments to bracket are in this order so that we can partially apply it, e.g.:withFile name mode = bracket (openFile name mode) hClose
Bracket wraps the release action with mask, which is sufficient to ensure that the release action executes to completion when it does not invoke any interruptible actions, even in the presence of asynchronous exceptions. For example, hClose is uninterruptible when it is not racing other uses of the handle. Similarly, closing a socket (from "network" package) is also uninterruptible under similar conditions. An example of an interruptible action is killThread. Completion of interruptible release actions can be ensured by wrapping them in uninterruptibleMask_, but this risks making the program non-responsive to Control-C, or timeouts. Another option is to run the release action asynchronously in its own thread:void $ uninterruptibleMask_ $ forkIO $ do { ... }
The resource will be released as soon as possible, but the thread that invoked bracket will not block in an uninterruptible state.bracket :: IO a -> (a -> IO b) -> (a -> IO c) -> IO cbase Control.Exception.Base When you want to acquire a resource, do some work with it, and then release the resource, it is a good idea to use bracket, because bracket will install the necessary exception handler to release the resource in the event that an exception is raised during the computation. If an exception is raised, then bracket will re-raise the exception (after performing the release). A common example is opening a file:
bracket (openFile "filename" ReadMode) (hClose) (\fileHandle -> do { ... })
The arguments to bracket are in this order so that we can partially apply it, e.g.:withFile name mode = bracket (openFile name mode) hClose
Bracket wraps the release action with mask, which is sufficient to ensure that the release action executes to completion when it does not invoke any interruptible actions, even in the presence of asynchronous exceptions. For example, hClose is uninterruptible when it is not racing other uses of the handle. Similarly, closing a socket (from "network" package) is also uninterruptible under similar conditions. An example of an interruptible action is killThread. Completion of interruptible release actions can be ensured by wrapping them in uninterruptibleMask_, but this risks making the program non-responsive to Control-C, or timeouts. Another option is to run the release action asynchronously in its own thread:void $ uninterruptibleMask_ $ forkIO $ do { ... }
The resource will be released as soon as possible, but the thread that invoked bracket will not block in an uninterruptible state.bracket :: IO a -> (a -> IO b) -> (a -> IO c) -> IO cbase GHC.IO No documentation available.
bracket :: (HasCallStack, MonadMask m) => m a -> (a -> m c) -> (a -> m b) -> m bexceptions Control.Monad.Catch Generalized abstracted pattern of safe resource acquisition and release in the face of errors. The first action "acquires" some value, which is "released" by the second action at the end. The third action "uses" the value and its result is the result of the bracket. If an error is thrown during the use, the release still happens before the error is rethrown. Note that this is essentially a type-specialized version of generalBracket. This function has a more common signature (matching the signature from Control.Exception), and is often more convenient to use. By contrast, generalBracket is more expressive, allowing us to implement other functions like bracketOnError.
bracket :: MonadUnliftIO m => m a -> (a -> m b) -> (a -> m c) -> m cunliftio UnliftIO.Exception Allocate and clean up a resource safely. For more information on motivation and usage of this function, see base's bracket. This function has two differences from the one in base. The first, and more obvious, is that it works on any MonadUnliftIO instance, not just IO. The more subtle difference is that this function will use uninterruptible masking for its cleanup handler. This is a subtle distinction, but at a high level, means that resource cleanup has more guarantees to complete. This comes at the cost that an incorrectly written cleanup function cannot be interrupted. For more information, please see https://github.com/fpco/safe-exceptions/issues/3.
bracket :: (HasCallStack, MonadMask m) => m a -> (a -> m b) -> (a -> m c) -> m csafe-exceptions Control.Exception.Safe Async safe version of bracket
bracket :: IO a -> (a -> IO b) -> (a -> IO c) -> IO cghc GHC.Utils.Exception No documentation available.
bracket :: MonadBaseControl IO m => m a -> (a -> m b) -> (a -> m c) -> m clifted-base Control.Exception.Lifted Generalized version of bracket. Note:
- When the "acquire" or "release" computations throw exceptions any monadic side effects in m will be discarded.
- When the "in-between" computation throws an exception any monadic side effects in m produced by that computation will be discarded but the side effects of the "acquire" or "release" computations will be retained.
- Also, any monadic side effects in m of the "release" computation will be discarded; it is run only for its side effects in IO.
liftBaseOp (bracket acquire release)
bracket :: MonadUnliftIO m => IO a -> (a -> IO b) -> (a -> m c) -> m ctyped-process System.Process.Typed.Internal No documentation available.
bracket :: Process a -> (a -> Process b) -> (a -> Process c) -> Process cdistributed-process Control.Distributed.Process Deprecated: Use Control.Monad.Catch.bracket instead
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