-- Hoogle documentation, generated by Haddock
-- See Hoogle, http://www.haskell.org/hoogle/
-- | Events and Channels as in Concurrent ML
--
-- Implementation of Events and Channels as in CML (extended with
-- communication guards). See A Concurrent ML Library in Concurrent
-- Haskell by Avik Chaudhuri (avik@cs.ucsc.edu) for details. The
-- original code as well as the papers can be found at
-- http://www.cs.umd.edu/~Eavik/projects/cmllch/.
@package cml
@version 0.1
-- | Events and Channels as in Concurrent ML (extended with communication
-- guards)
--
-- See A Concurrent ML Library in Concurrent Haskell by Avik
-- Chaudhuri (avik@cs.ucsc.edu). The original code as well as the papers
-- can be found at http://www.cs.umd.edu/~Eavik/projects/cmllch/.
--
-- User-visible changes to the original code:
--
--
-- - Event and Channel are now abstract types
-- - renamed new to channel
-- - export list, hierarchical module name & similar goodies
--
module Control.Concurrent.CML
-- | Values of type a can be transported over channels of type
-- Channel a.
data Channel a
-- | Create a new channel.
channel :: IO (Channel a)
-- | Receive a message from a channel.
--
-- More precisely, receive c cond returns an event that, on
-- synchronization, accepts a message m on channel c
-- and returns m. The resulting event is eligible for
-- synchronization with a transmit c m only if cond m
-- is true.
receive :: Channel a -> (a -> Bool) -> Event a
-- | Transmit a message over a channel.
--
-- More precisely, transmit c m returns an event that, on
-- synchronization, sends the message m on channel c
-- and returns (). Such an event must synchronize with
-- receive c.
transmit :: Channel a -> a -> Event ()
-- | Events return a value on synchronization.
--
-- Note that by construction, an event can synchronize at exactly one
-- commit point, where a message is either sent or accepted on a
-- channel. This commit point may be selected among several other,
-- potential commit points. Some code may be run before synchronization,
-- as specified by guard functions throughout the event. Some more
-- code may be run after synchronization, as specified by wrap
-- functions that surround the commit point, and by wrapabort
-- functions that do not surround the commit point.
data Event a
-- | Synchronize an event.
--
-- This blocks the calling thread until a matching event is available.
sync :: Event a -> IO a
-- | Non-deterministically select an event from a list of events, so that
-- the selected event can be synchronized. The other events in the list
-- are aborted.
choose :: [Event a] -> Event a
-- | Specify a post-synchronization action.
--
-- More precisely, wrap v f returns an event that, on
-- synchronization, synchronizes the event v and then runs the
-- action returned by f applied to the result.
wrap :: Event a -> (a -> IO b) -> Event b
-- | Specify a pre-synchronization action.
--
-- More precisely, guard a returns an event that, on
-- synchronization, synchronizes the event returned by the action
-- a. Here, a is run every time a thread tries
-- to synchronize guard a.
guard :: IO (Event a) -> Event a
-- | Specify a post-synchronization action that is spawned if an event is
-- not selected by a choose.
--
-- More precisely, wrapabort a v returns an event that, on
-- synchronization, synchronizes the event v, and on abortion,
-- spawns a thread that runs the action a. Here, if v
-- itself is of the form choose vs and one of the events in
-- vs is selected, then v is considered selected, so
-- a is not spawned.
wrapabort :: IO () -> Event a -> Event a
-- | A synonym for forkIO.
spawn :: IO () -> IO ThreadId