-- Hoogle documentation, generated by Haddock
-- See Hoogle, http://www.haskell.org/hoogle/

-- | Safety for the pipes ecosystem
--   
--   This package adds resource management and exception handling to the
--   pipes ecosystem.
--   
--   Notable features include:
--   
--   
--   
- Resource Safety: Guarantee finalization using
--   finally, bracket and more
--   
- Exception Safety: Even against asynchronous
--   exceptions!
--   
- Laziness: Only acquire resources when you need them
--   
- Promptness: Finalize resources early when you are done with
--   them
--   
- Native Exception Handling: Catch and resume from exceptions
--   inside pipes
--   
- No Buy-in: Mix resource-safe pipes with unmanaged pipes
--   using hoist
--   
@package pipes-safe
@version 2.0.2

-- | This module provides an orphan MonadCatch instance for
--   Proxy of the form:
--   
--   
--   instance (MonadCatch m, MonadIO m) => MonadCatch (Proxy a' a b' b m) where
--   
--   
--   ... so you can throw and catch exceptions within pipes using all
--   MonadCatch operations.
--   
--   This module also provides generalized versions of some
--   MonadCatch operations so that you can also protect against
--   premature termination of connected components. For example, if you
--   protect a readFile computation using bracket from this
--   module:
--   
--   
--   -- readFile.hs
--   import Pipes
--   import qualified Pipes.Prelude as P
--   import Pipes.Safe
--   import qualified System.IO as IO
--   import Prelude hiding (readFile)
--   
--   readFile :: FilePath -> Producer' String (SafeT IO) ()
--   readFile file = bracket
--       (do h <- IO.openFile file IO.ReadMode
--           putStrLn $ "{" ++ file ++ " open}"
--           return h )
--       (\h -> do
--           IO.hClose h
--           putStrLn $ "{" ++ file ++ " closed}" )
--       P.fromHandle
--   
--   
--   ... then this generalized bracket will guard against both
--   exceptions and premature termination of other pipes:
--   
--   
--   >>> runSafeT $ runEffect $ readFile "readFile.hs" >-> P.take 4 >-> P.stdoutLn
--   {readFile.hs open}
--   -- readFile.hs
--   import Pipes
--   import qualified Pipes.Prelude as P
--   import Pipes.Safe
--   {readFile.hs closed}
--   
--   
--   Note that the MonadCatch instance for Proxy provides
--   weaker versions of mask and uninterruptibleMask that do
--   not completely prevent asynchronous exceptions. Instead, they provide
--   a weaker guarantee that asynchronous exceptions will only occur during
--   awaits or yields and nowhere else. For example, if you
--   write:
--   
--   
--   mask_ $ do
--       x <- await
--       lift $ print x
--       lift $ print x
--   
--   
--   ... then you may receive an asynchronous exception during the
--   await, but you will not receive an asynchronous exception
--   during or in between the two print statements. This weaker
--   guarantee suffices to provide asynchronous exception safety.
module Pipes.Safe

-- | SafeT is a monad transformer that extends the base monad with
--   the ability to register and release finalizers.
--   
--   All unreleased finalizers are called at the end of the SafeT
--   block, even in the event of exceptions.
data SafeT m r

-- | Run the SafeT monad transformer, executing all unreleased
--   finalizers at the end of the computation
runSafeT :: (MonadCatch m, MonadIO m) => SafeT m r -> m r

-- | Run SafeT in the base monad, executing all unreleased
--   finalizers at the end of the computation
--   
--   Use runSafeP to safely flush all unreleased finalizers and
--   ensure prompt finalization without exiting the Proxy monad.
runSafeP :: (MonadCatch m, MonadIO m) => Effect (SafeT m) r -> Effect' m r

-- | Token used to release a previously registered finalizer
data ReleaseKey

-- | MonadSafe lets you register and release
--   finalizers that execute in a Base monad
class (MonadCatch m, MonadIO m, MonadIO (Base m)) => MonadSafe m where type family Base (m :: * -> *) :: * -> *
liftBase :: MonadSafe m => Base m r -> m r
register :: MonadSafe m => Base m () -> m ReleaseKey
release :: MonadSafe m => ReleaseKey -> m ()

-- | Analogous to onException from Control.Monad.Catch,
--   except this also protects against premature termination
--   
--   (`onException` io) is a monad morphism.
onException :: MonadSafe m => m a -> Base m b -> m a

-- | Analogous to finally from Control.Monad.Catch, except
--   this also protects against premature termination
finally :: MonadSafe m => m a -> Base m b -> m a

-- | Analogous to bracket from Control.Monad.Catch, except
--   this also protects against premature termination
bracket :: MonadSafe m => Base m a -> (a -> Base m b) -> (a -> m c) -> m c

-- | Analogous to bracket_ from Control.Monad.Catch, except
--   this also protects against premature termination
bracket_ :: MonadSafe m => Base m a -> Base m b -> m c -> m c

-- | Analogous to bracketOnError from Control.Monad.Catch,
--   except this also protects against premature termination
bracketOnError :: MonadSafe m => Base m a -> (a -> Base m b) -> (a -> m c) -> m c
instance (MonadSafe m, Monoid w) => MonadSafe (RWST i w s m)
instance (MonadSafe m, Monoid w) => MonadSafe (RWST i w s m)
instance (MonadSafe m, Monoid w) => MonadSafe (WriterT w m)
instance (MonadSafe m, Monoid w) => MonadSafe (WriterT w m)
instance MonadSafe m => MonadSafe (StateT s m)
instance MonadSafe m => MonadSafe (StateT s m)
instance MonadSafe m => MonadSafe (ReaderT i m)
instance MonadSafe m => MonadSafe (CatchT m)
instance MonadSafe m => MonadSafe (IdentityT m)
instance MonadSafe m => MonadSafe (Proxy a' a b' b m)
instance (MonadIO m, MonadCatch m) => MonadSafe (SafeT m)
instance MonadTrans SafeT
instance MonadCatch m => MonadCatch (SafeT m)
instance MonadIO m => MonadIO (SafeT m)
instance Monad m => Monad (SafeT m)
instance Monad m => Applicative (SafeT m)
instance Monad m => Functor (SafeT m)
instance (MonadCatch m, MonadIO m) => MonadCatch (Proxy a' a b' b m)

-- | Simple resource management functions
module Pipes.Safe.Prelude

-- | Acquire a Handle within MonadSafe
withFile :: MonadSafe m => FilePath -> IOMode -> (Handle -> m r) -> m r

-- | Read lines from a file, automatically opening and closing the file as
--   necessary
readFile :: MonadSafe m => FilePath -> Producer' String m ()

-- | Write lines to a file, automatically opening and closing the file as
--   necessary
writeFile :: MonadSafe m => FilePath -> Consumer' String m r
