- Haskell-Cafe - Haskell.org

LFM for Haskell bittorrent effort
by Mateusz Kowalczyk 01 Sep '14

01 Sep '14

Hi, For this or another reason, no bittorrent libraries/clients available today seem to suit my needs: they are either too slow, too memory inefficient, bundled with a client which often can't run in a headless environment or broken in some other way or don't implement all the common BEPs. I came to the conclusion that I'll probably have to write one. Happily, whenever I mentioned the topic in #haskell, there was quite a bit of interest each time so I'm looking to recruit people to join me in this effort. First a brief overlook of what's already available in the Haskell environment: * Combinatorrent[1] – a rather old client, no longer maintained with the last Hackage upload in 2010. Only supports few BEPs and was not able to load in the .torrent file provided by Ubuntu. I have spoken to jlouis who wrote this, you can read the conversation at [2]. He himself says that nowadays you can do better performance wise with available libraries. Additionally, this comes with a client on top rather than just being a library. * conjure – not touched since 2008 * bittorrent – seems to be the closest to what I'd like but it is still incomplete and the library is in limbo. There is a lot of stuff that does not work or is commented out and for various reasons the maintainer is unavailable to help out. I have spoken to the maintainer and he himself would like to redesign the library. That's about it. There seem to be a few related tools for bencoding &c but nothing huge. I think the best way to go about this is to learn from Combinatorrent and bittorrent and start something fresh. I'll outline the goals I personally am looking for even though they might be obvious: * efficient, scalable – the library needs to be able to handle tens of thousands of active (announcing, not necessarily downloading) torrents at once. For reference, libtorrent-rakshasa + rtorrent is able to run about ~10k torrents in about 1GB of memory with low CPU usage. The downside is that the library crashes like no tomorrow and the client itself sucks. A slow library is useless to me but so is a fast but unstable one. * implements all the common BEPs – no use for a library if it doesn't work for a lot of cases. It needs to implement everything from [3] maybe except BEP 8. * sane interface – in the end we need to be able to build clients on top. Fortunately we can leverage Haskell's types to do this whereas the existing C/C++ bittorrent libraries seems to suffer badly here. * resilient – if I wanted a fast library which crashes every ten minutes I'd stick with libtorrent Basically, I'm looking to build a fully usable bittorrent library. Notably, I'm not looking for people to help to write a client (yet!). I plan to start as soon as time allows but it'd be great if there was more than just myself on board. Let me know one way another if you're interested in contributing. If you're just interested in the final product then that's fine too, I could always use more motivation! [1]: https://github.com/jlouis/combinatorrent [2]: http://ircbrowse.net/browse/haskell?id=18701612&timestamp=1406738464#t14067… [3]: http://www.bittorrent.org/beps/bep_0000.html -- Mateusz K.

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Set (Set a) like container - but more efficient?
by Marc Weber 01 Sep '14

01 Sep '14

Does a Set (Set a) like container exist already but which is represented as tree internally, eg A ` - B - C ` - D ` - X - Y which would represent ABC ABD and AXY ? If it does not what would be a nice name to create such container? Marc Weber

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Diony Rosa
by Diony Rosa 01 Sep '14

01 Sep '14

http://www.sarah-aloisi.com/ftpkk/lbqwswuvjc.ocrjttewxqiidnzuutwvyhq

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cabal sdist and auto-generated modules
by Marios Titas 31 Aug '14

31 Aug '14

I am trying to run cabal sdist on a package where one of exposed modules does not exists because it is automatically generated by setup.hs. cabal refuses to do that because it cannot find the file corresponding to that module. Is there a solution to that problem? The package builds just fine.

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RTS options to control name of eventlog file.
by Serguey Zefirov 31 Aug '14

31 Aug '14

Is there any? Because when running and profiling two same programs they will write into same eventlog file. Not a good situation.

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[ANN] igrf-0.2
by Douglas McClean 31 Aug '14

31 Aug '14

igrf is a library that provides an implementation of the International Geomagnetic Reference Field, which is just what it sounds like. I've tested it against NOAA's online calculator, but use it at your own risk. Note that the input is in geocentric and not geodetic coordinates. There is haddock documentation, I'm working on figuring out why it isn't on hackage and how to fix it. -Doug McClean

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Monads vs Linear regions
by Timotej Tomandl 30 Aug '14

30 Aug '14

How do they compare? Can Linear regions handle all uses of monads or does they lack some applications?

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Fwd: Linear regions ("Linear Regions Are All You Need") as the only way of encapsulation of impure state
by Timotej Tomandl 30 Aug '14

30 Aug '14

I was thinking for a while about if other kinds of handling of impure state have any advantages over linear regions. So I thought it will be nice to open the discussion about how does it compare with monads, linear types, uniqueness typing and monadic regions.

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[ANN] codex 0.1.0.4
by Alois Cochard 30 Aug '14

30 Aug '14

Hi Cafe, I just wanted to let you know that I have just released a new version of `codex` on hackage. There is *no new features* in this version, but thanks for the help from Hubert Behaghel I was able to investigate issues with MacOS. So basically this version now work with MacOS, if you had give a try before please delete your "~/.codex" configuration file before installing the new version. Cheers -- *Λ\ois* http://twitter.com/aloiscochard http://github.com/aloiscochard

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ICFP pre-party
by Roman Cheplyaka 30 Aug '14

30 Aug '14

We're having a small unofficial ICFP pre-party today in Gothenburg. All haskell-cafe readers that happen to be in Gothenburg are welcome :-) The plan is to meet at The Bishop's Arms (Kungsportsavenyen 36) at 19.00. NOTE: there are three Bishop's Arms in Gothenburg, so mind the address. Feel free to text me at +380662285780. Roman

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