2016-06-20 23:45:34 +03:00
|
|
|
concurrency
|
|
|
|
|
===========
|
|
|
|
|
|
|
|
|
|
A typeclass abstraction over much of Control.Concurrent (and some
|
|
|
|
|
extras!). If you're looking for a general introduction to Haskell
|
|
|
|
|
concurrency, you should check out the excellent
|
|
|
|
|
[Parallel and Concurrent Programming in Haskell][parconc], by Simon
|
|
|
|
|
Marlow. If you are already familiar with concurrent Haskell, just
|
|
|
|
|
change all the imports from Control.Concurrent.* to
|
|
|
|
|
Control.Concurrent.Classy.* and fix the type errors.
|
|
|
|
|
|
|
|
|
|
A brief list of supported functionality:
|
|
|
|
|
|
|
|
|
|
- Threads: the `forkIO*` and `forkOn*` functions, although bound
|
|
|
|
|
threads are not supported.
|
|
|
|
|
- Getting and setting capablities.
|
|
|
|
|
- Yielding and delaying.
|
|
|
|
|
- Mutable state: STM, `MVar`, and `IORef`.
|
|
|
|
|
- Atomic compare-and-swap for `IORef`.
|
|
|
|
|
- Exceptions.
|
|
|
|
|
- All of the data structures in Control.Concurrent.* and
|
|
|
|
|
Control.Concurrent.STM.* have typeclass-abstracted equivalents.
|
|
|
|
|
|
|
|
|
|
This is quite a rich set of functionality, although it is not
|
|
|
|
|
complete. If there is something else you need, file an issue!
|
|
|
|
|
|
|
|
|
|
This used to be part of dejafu, but with the dejafu-0.4.0.0 release,
|
|
|
|
|
it was split out into its own package.
|
|
|
|
|
|
|
|
|
|
The documentation of the latest developmental version is
|
|
|
|
|
[available online][docs].
|
|
|
|
|
|
2016-09-10 15:58:59 +03:00
|
|
|
Why this and not something else?
|
|
|
|
|
--------------------------------
|
2016-09-10 14:39:34 +03:00
|
|
|
|
|
|
|
|
- **Why not base:** like lifted-base, concurrency uses typeclasses to
|
|
|
|
|
make function types more generic. This automatically eliminates
|
|
|
|
|
calls to `lift` in many cases, resulting in clearer and simpler
|
|
|
|
|
code.
|
|
|
|
|
|
|
|
|
|
- **Why not lifted-base:** fundamentally, lifted-base is still using
|
|
|
|
|
actual threads and actual mutable variables. When using a
|
|
|
|
|
concurrency-specific typeclass, this isn't necessarily the case. The
|
|
|
|
|
dejafu library provides non-IO-based implementations to allow
|
|
|
|
|
testing concurrent programs.
|
|
|
|
|
|
|
|
|
|
- **Why not IOSpec:** IOSpec provides many of the operations this
|
|
|
|
|
library does, however it uses a free monad to do so, which has extra
|
|
|
|
|
allocation overhead. Furthermore, it does not expose enough of the
|
|
|
|
|
internals in order to accurately test real-execution semantics, such
|
|
|
|
|
as relaxed memory.
|
|
|
|
|
|
2016-06-20 23:45:34 +03:00
|
|
|
Contributing
|
|
|
|
|
------------
|
|
|
|
|
|
|
|
|
|
Bug reports, pull requests, and comments are very welcome!
|
|
|
|
|
|
|
|
|
|
Feel free to contact me on GitHub, through IRC (#haskell on freenode),
|
|
|
|
|
or email (mike@barrucadu.co.uk).
|
|
|
|
|
|
|
|
|
|
[docs]: https://docs.barrucadu.co.uk/concurrency/dejafu-0.4
|
|
|
|
|
[parconc]: http://chimera.labs.oreilly.com/books/1230000000929
|
