|This module contains all the central monads in the CHP library.
|The central monad of the library. You can use
Control.Concurrent.CHP.Monad.runCHP_ to execute programs in this
|A monad transformer class that is very similar to MonadIO. This can be
useful if you want to add monad transformers (such as StateT, ReaderT) on
top of the CHP monad.
|Runs a CHP program. You should use this once, at the top-level of your
program. Do not ever use this function twice in parallel and attempt to
communicate between those processes using channels. Instead, run this function
once and use it to spawn off the parallel processes that you need.
|Runs a CHP program. Like runCHP but discards the output.
Allows embedding of the CHP monad back into the IO monad. The argument
that this function takes is a CHP action (with arbitrary behaviour). The
function is monadic, and returns something of type: IO a. This
is an IO action that you can now use in the IO monad wherever you like.
What it returns is the result of your original action.
This function is intended for use wherever you need to supply an IO callback
(for example with the OpenGL libraries) that needs to perform CHP communications.
It is the safe way to do things, rather than using runCHP twice (and also works
with CSP and VCR traces -- but not structural traces!).
|A convenient version of embedCHP that ignores the result
|A helper like embedCHP for callbacks that take an argument
|A convenient version of embedCHP1 that ignores the result
Allows you to provide a handler for sections with poison. It is usually
used in an infix form as follows:
(readChannel c >>= writeChannel d) `onPoisonTrap` (poison c >> poison d)
It handles the poison and does not rethrow it (unless your handler
does so). If you want to rethrow (and actually, you'll find you usually
do), use onPoisonRethrow
Like onPoisonTrap, this function allows you to provide a handler
for poison. The difference with this function is that even if the
poison handler does not throw, the poison exception will always be
re-thrown after the handler anyway. That is, the following lines of
code all have identical behaviour:
foo `onPoisonRethrow` throwPoison
foo `onPoisonRethrow` return ()
|Throws a poison exception.
|class Poisonable c where||Source|
|A class indicating that something is poisonable.
|Poisons the given item.
Checks if the given item is poisoned. If it is, a poison exception
will be thrown.
Added in version 1.0.2.
|Poisons all the given items. A handy shortcut for mapM_ poison.
|A monad transformer for easier looping. This is independent of the
CHP aspects, but has all the right type-classes defined for it to make
it easy to use with the CHP library.
|Runs the given action in a loop, executing it repeatedly until a while
statement inside it has a False condition. If you use loop without while,
the effect is the same as forever.
|Continues executing the loop if the given value is True. If the value
is False, the loop is broken immediately, and control jumps back to the
next action after the outer loop statement. Thus you can build pre-condition,
post-condition, and "mid-condition" loops, placing the condition wherever
The classic skip process/guard. Does nothing, and is always ready.
Suitable for use in an Control.Concurrent.CHP.Alt.alt.
The stop guard. Its main use is that it is never ready in a choice, so
can be used to mask out guards. If you actually execute stop, that process
will do nothing more. Any parent process waiting for it to complete will
The type of this function was generalised in CHP 1.6.0.
Waits for the specified number of microseconds (millionths of a second).
There is no guaranteed precision, but the wait will never complete in less
time than the parameter given.
Suitable for use in an Control.Concurrent.CHP.Alt.alt, but note that waitFor 0 is not the same
as skip. waitFor 0 Control.Concurrent.CHP.Alt.</> x will not always select the first guard,
depending on x. Included in this is the lack of guarantee that
waitFor 0 Control.Concurrent.CHP.Alt.</> waitFor n will select the first guard for any value
of n (including 0). It is not useful to use two waitFor guards in a
single Control.Concurrent.CHP.Alt.alt anyway.
NOTE: If you wish to use this as part of a choice, you must use -threaded
as a GHC compilation option (at least under 6.8.2).
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