April 2010 - Haskell-Cafe

ANN: fastirc 0.2.0
by Ertugrul Soeylemez 01 Apr '10

01 Apr '10

[For some reason, my Mail to the 'haskell' list was rejected. I have contacted the mailing list owner and am posting here instead.] Hello there fellow Haskellers, I'm developing a library called 'fastirc' for fast and convenient Internet Relay Chat (IRC) software development. It uses attoparsec and ByteStrings and the latest release also includes a client framework, which you can use to write bots and user agents easily. Here is the Hackage page: http://hackage.haskell.org/package/fastirc Even though I marked the library as 'alpha' quality, it seems to work well currently. Feel free to try it out and if you find anything odd, just drop me a message (or a patch). =) If you would like to contribute, please contact me first, so I can tell you whether your ideas would be incorporated into the 'fastirc' package or whether it would be better to fork off a new project. By the way, please note that although unlikely right now the interface might change slightly from release to release. I'm planning to stabilize it by version 0.4.0. Also note that the library uses monadLib instead of mtl/transformers, where the monad transformer interface is slightly different. Particularly inside the 'Bot' monad you can run IO computations using 'inBase' instead of 'liftIO'. For more differences, just read the monadLib docs. I hope it will be useful. Greets, Ertugrul -- nightmare = unsafePerformIO (getWrongWife >>= sex) http://blog.ertes.de/

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Re: [Haskell-cafe] Where are the haskell elders?
by gladstein＠gladstein.com 01 Apr '10

01 Apr '10

>Perhaps without spewing it to thousands of readers while you're at it? Ahem.

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new focus for Happstack
by Jeremy Shaw 01 Apr '10

01 Apr '10

Hello, I've been thinking a lot recently about the direction and future of the Happstack project. These days we hear a lot about technologies to allow servers to push data, such as Comet, Ajax Push, Reverse Ajax, Two-way-web, HTTP Streaming, and HTTP server push among others. HTML 5 includes something called 'Web Sockets'. In short, it seems that the 'stateless' web model is a complete failure. People want sockets! Furthermore, the big sites of the day are 'social media' sites such as Facebook, Twitter, Youtube, Four Square, etc. Well, it's clear to me where the industry is headed, and I think this is a great chance for Haskell to be the leader. persistent connection + social web site == BBS That's right! The return of the BBS is upon us. So, without further ado, I would like to announce the happstack-bbs project: darcs get http://src.seereason.com/happstack-bbs/ You can connect right now to the world's newest Haskell BBS. Simple open a terminal which supports ansi & utf-8, and run: telnet hacketeria.com 2525 Patches welcome (and sorely needed!) - jeremy

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Intro to Haskell Crypto Libs
by Günther Schmidt 01 Apr '10

01 Apr '10

Hi all, I'm just starting with Haskells Crypto Libs. Is there a good intro to the subject? I intend to use it for license key generation. Günther

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benchmarking pure code
by Paul Brauner 01 Apr '10

01 Apr '10

Hello, I'm writing a library for dealing with binders and I want to benchmark it against DeBruijn, Locally Nameless, HOAS, etc. One on my benchmark consists in 1. generating a big term \x.t 2. substituting u fox in t The part I want to benchmark is 2. In particular I would like that: a. \x.t is already evaluated when I run 2 (I don't want to measure the performances of the generator) b. the action of substituting u for x in t were measured as if I had to fully evaluate the result (by printing the resulting term for instance). After looking at what was available on hackage, i set my mind on strictbench, which basically calls (rnf x `seq` print "") and then uses benchpress to measure the pure computation x. Since I wanted (a), my strategy was (schematically): let t = genterm rnf t `seq` print "" bench (subst u t) I got numbers I didn't expect so I ran the following program: let t = genterm print t bench (subst u t) and then I got other numbers! Which were closer to what I think they should be, so I may be happy with them, but all of this seems to indicate that rnf doesn't behave as intended. Then I did something different: I wrote two programs. One that prints the result of (subst u t): let t = genterm let x = (subst u t) print x bench (print x) recorded the numbers of that one and then ran the program: let t = genterm bench (print (subst u t)) got the numbers, and substracted the first ones to them. By doing so, I'm sure that I get realistic numbers at least: since I print the whole resulting term, I've got a visual "proof" that it's been evaluated. But this is not very satisfactory. Does anyone have an idea why calling rnf before the bench doesn't seem to "cache" the result as calling show does? (my instances of NFData follow the scheme described in strictbench documentation). If not, do you think that measuring (computation + pretty printing time - pretty printing time) is ok? Regards, Paul

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why doesn't time allow diff of localtimes ?
by briand＠aracnet.com 01 Apr '10

01 Apr '10

which is a variation of the question, why can't I compare localtimes ? or am I missing something in Time (yet again). Thanks, Brian

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Re: building "encoding" on Windows?
by John Lato 01 Apr '10

01 Apr '10

> From: Andrew Coppin <andrewcoppin(a)btinternet.com> > >> A new version is due to be release >> pretty soon (somewhere begin april). It has Mingw and Msys included, and >> also some pre-built binaries like cabal and haddock. > > Plain GHC has included Haddock for a while now. It seems to me that > including the entirity of MinGW and MSYS is overkill, but what do I know > about the matter? I was however under the impression that to use Unix > emulators such as these, you have to run everything from a seperate > shell rather than the usual Windows shell. MSys is probably unnecessary, but mingw is necessary to to get configure scripts to run. I wholeheartedly applaud including both of these, because a lot more of hackage will really be just a "cabal install" away. MSys is the separate shell, but you can use mingw with the Windows "cmd" shell if you wish. > > My hope is that the more useful C libraries will get added to HP so that > I can start using them. (E.g., I'd love to be able to do sound synthesis > using Haskell, but there aren't any libraries for accessing the sound > hardware...) I've gotten portaudio to work on Windows. You'll probably need to build and install the C portaudio library manually. John

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ANN: logfloat 0.12.1
by wren ng thornton 01 Apr '10

01 Apr '10

-------------------------------------------- -- logfloat 0.12.1 -------------------------------------------- This package provides a type for storing numbers in the log-domain, primarily useful for preventing underflow when multiplying many probabilities as in HMMs and other probabilistic models. The package also provides modules for dealing with floating numbers correctly. -------------------------------------------- -- Changes since 0.12.0.1 -------------------------------------------- * Fixed a number of bugs where LogFloat values would become NaN when they should not. These bugs involved using normal-space positive infinity and so would not affect clients using the package for probabilities. The fixes do introduce some extra checks though. If anyone is using the package for probabilities in a large enough project and could run some benchmarks to see how 0.12.1 compares to 0.12.0.1 I'd love to hear the results. (I'm not sure that doing microbenchmarks would actually give much insight about real programs.) If the overhead is bad enough I can add a LogProb type which ensures things are proper probabilities in order to avoid the new checks. -------------------------------------------- -- Compatibility / Portability -------------------------------------------- The package is compatible with Hugs (September 2006) and GHC (6.8, 6.10, 6.12). For anyone still using GHC 6.6, the code may still work if you replace LANGUAGE pragma by equivalent OPTIONS_GHC pragma. The package is not compatible with nhc98 and Yhc because Data.Number.RealToFrac uses MPTCs. The other modules should be compatible. -------------------------------------------- -- Links -------------------------------------------- Homepage: http://code.haskell.org/~wren/ Hackage: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/logfloat Darcs: http://code.haskell.org/~wren/logfloat/ Haddock (Darcs version): http://code.haskell.org/~wren/logfloat/dist/doc/html/logfloat/ -- Live well, ~wren

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Re: Trying to figure out a segfault caused by haskeline.
by ryan winkelmaier 31 Mar '10

31 Mar '10

Hi, Nobody seems to have any idea what is happening yet. Though thanks for trying dagit (forgot to add haskell-cafe to my repliess to him). Quick update incase it helps, compiling with profiling and running with the -xc option results in, <Main.CAF:runInputT_rOA><System.Posix.Files.CAF>Segmentation fault I'm still working on it but could it be the configuration file? thats the thing the haskeline accesses files for right? On Mon, Mar 29, 2010 at 8:28 PM, ryan winkelmaier <syfran92(a)gmail.com>wrote: > Hey everyone, > > I'm looking for help with a seg fault that takes out both my ghci and darcs > as well as anything that uses haskeline. A bug on the haskeline trac hasn't > gotten any response so I figured I might as well figure this out myself and > get ghci up and running again. > > Using the test program below I get the same segmentation fault, so I run it > using gdb and get the following, > > Program received signal SIGSEGV, Segmentation fault. > 0x000000000053fdce in base_ForeignziCziString_zdwa_info () > > My knowledge of this is very limited from here on out so here is what I was > able to get together. > > On the 20th call of base_ForeignziCziString_zdwa_info > r14 is 0 so > > 0x000000000053fdce <+22>: movsbq (%r14),%rax > > produces the segfault. > From what I understand this is happening in the Foreign.C.String module but > thats as much as I know. > Anyone have advice on where to go next? > > System info: > Distribution: gentoo amd64 > Ghc version: currently 6.12.1 (though the segfault happends on any of the > ones with haskeline) > Haskeline version: 0.6.2.2 > > Here is the test program > > > ---------------------------------------------------------------------------------------------------- > module Main where > > import System.Console.Haskeline > import System.Environment > > {-- > Testing the line-input functions and their interaction with ctrl-c signals. > > Usage: > ./Test (line input) > ./Test chars (character input) > --} > > mySettings :: Settings IO > mySettings = defaultSettings {historyFile = Just "myhist"} > > main :: IO () > main = do > args <- getArgs > let inputFunc = case args of > ["chars"] -> fmap (fmap (\c -> [c])) . getInputChar > _ -> getInputLine > runInputT mySettings $ withInterrupt $ loop inputFunc 0 > where > loop inputFunc n = do > minput <- handleInterrupt (return (Just "Caught interrupted")) > $ inputFunc (show n ++ ":") > case minput of > Nothing -> return () > Just "quit" -> return () > Just "q" -> return () > Just s -> do > outputStrLn ("line " ++ show n ++ ":" ++ s) > loop inputFunc (n+1) > > ------------------------------------------------------------------------------------------------------------------------ > > > Syfran >

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