dejafu- Overloadable primitives for testable, potentially non-deterministic, concurrency.

Copyright(c) 2016 Michael Walker
MaintainerMichael Walker <>
Safe HaskellNone




Unbounded channels.

Deviations: Chan as defined here does not have an Eq instance, this is because the MonadConc MVar type does not have an Eq constraint. The deprecated unGetChan and isEmptyCHan functions are not provided. Furthermore, the getChanContents function is not provided as it needs unsafe I/O.


The Chan type

data Chan m a Source #

Chan is an abstract type representing an unbounded FIFO channel.


newChan :: MonadConc m => m (Chan m a) Source #

Build and returns a new instance of Chan.

writeChan :: MonadConc m => Chan m a -> a -> m () Source #

Write a value to a Chan.

readChan :: MonadConc m => Chan m a -> m a Source #

Read the next value from the Chan.

dupChan :: MonadConc m => Chan m a -> m (Chan m a) Source #

Duplicate a Chan: the duplicate channel begins empty, but data written to either channel from then on will be available from both. Hence this creates a kind of broadcast channel, where data written by anyone is seen by everyone else.

Stream interface

writeList2Chan :: MonadConc m => Chan m a -> [a] -> m () Source #

Write an entire list of items to a Chan.