Re: [Haskell-cafe] ghc 6.8.1 bug?
Hello, I have had exactly the same problem with my bindings to GSL, BLAS and LAPACK. The foreign functions (!) randomly (but very frequently) produced NaN with ghc-6.8.1 -O. As usual, I first thought that I had a subtle bug related to the foreign pointers, but after a lot of refactoring, experiments, and tracing everything, I'm reasonably sure that memory is safely used. What I have found is that the same errors can be reproduced on ghc-6.6.1 with -O -fasm. So I tried -O -fvia-C on ghc-6.8.1 (which now it is not the default) and apparently everything works well. So it seems that now the ffi requires and additional and explicit -fvia-C. In any case I don't know why -fasm produces those strange NaN in precompiled foreign functions... Alberto On Thursday 15 November 2007 09:05, SevenThunders wrote: The good news is that my code compiles without error and much faster under ghc 6.8.1. The bad news is that there appear to be subtle bugs that did not occur when I compiled things under 6.6.1. One issue is that my code is somewhat complex and links into a C library as well. The new behavior is that under certain conditions a certain matrix inner product produces undefined floats, that should not be there. If the code is executed inside any function it fails but if the same code is reexecuted at the ghci prompt it works. Here is the gist of the code that I'm running main = do ... lots of computations and let clauses -- get a submatrix viewMatbotk wstart nsua su 1 suw -- get another submatrix viewMatbotk 0 nsua arrstart npaths sua -- complex non conjugated inner product (multiply the two submatrices) mulCFtF mprint If this is executed either in ghci as main or from a Dos prompt I get a matrix filled with bad values including a few that look like -1.#IND+1.87514i If I recompile everything in ghc-6.6.1 it works like charm. I make sure that I have deleted all the .o and .hi files. There is a dll that contains a C library I link to via running dlltool.exe. If I print out all the function inputs to the function viewMatbotk and then call them interactively in ghc 6.8.1 and call mulCFtF interactively it works correctly. both viewMatbotk and mulCFtF are C routines pulled in from the external library. I am at a complete loss how to debug this or how to pin down what exactly has changed between 6.6.1 and 6.8.1 that breaks this code so badly. This type of error stinks of some kind of memory issue, e.g. corrupted pointers. Any suggestions would be appreciated. Unfortunately the code base is rather involved and potentially proprietary so I can't publish all of the details. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Why are OCaml and Haskell being used at these companies?
Seth Gordon [EMAIL PROTECTED] writes: Bioinformaticians are among the first to adopt functional programming languages From my experience, Bioinformatics use a mixture of langauges - C to implement various algorithms, a bit of Java for UI-oriented stuff, and Perl to tie it all together. (You can use Python instead, of course, but expect to be considered something of a rebel.) I think Haskell works nicely to combine at least the C and Perl aspects, but as far as I can tell, I'm about the only one who does this. There isn't a lot of comp.sci. in bioinformatics, beyond a handful of relatively standard algorithms. I guess it's one of those practical fields. I guess the important difference to the financial sector is that the competitive advantage is in exclusive data, not exclusive algorithms or analytical methods. Thus, programmer productivity isn't quite so important, you're just going to script togehter some pre-packaged tools, often ten or fifteen year old software. FWIW, a few years ago, when I was stubbornly unemployed[*], I wrangled a fifteen-minute informational interview with Kenan Sahin[**]. He advised me to look for work related to medical devices Sounds like good advice to me - pharmaceuticals seem to have enough money, at least. -k -- If I haven't seen further, it is by standing in the footprints of giants ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Using Data.Binary for compression
Hello Chad, Thursday, November 15, 2007, 9:03:52 AM, you wrote: I'd like to be able to use Data.Binary (or similar) for compression. Say I have an abstract type Symbol, and for each value of Symbol I have a representation in terms of some number of bits. For compression to be efficient, commonly-used Symbols should have very short representations, while less common ones can be longer. alternative may be using naive representation for serializing and then running zip/bzip2 compression lib over it. it should be both faster and provide better compression -- Best regards, Bulatmailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] let vs. where
On Tue, 13 Nov 2007, Dan Piponi wrote: On Nov 13, 2007 1:24 PM, Ryan Ingram [EMAIL PROTECTED] wrote: I tend to prefer where, but I think that guards function declarations are more readable than giant if-thens and case constructs. Up until yesterday I had presumed that guards only applied to functions. But I was poking about in the Random module and discovered that you can write things like a | x 1 = 1 | x -1 = -1 | otherwise = x Btw. I would write here min 1 (max (-1) x) or even better define a function for such clipping, since it is needed quite often. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Weird ghci behaviour?
Simon Marlow wrote: The only problem with this is that someone who isn't aware of this convention might accidentally be ignoring compiled code, or might wonder why their compiled code isn't being used. Well, perhaps this is less confusing than the current behaviour; personally I find the current behaviour consistent and easy to understand, but I guess I'm in the minority! Anecdotes have little value, but for what it's worth: in around 5 years of ghc use, I have never, not even once, wanted to load the module I was working on in its compiled form. I've occasionally noticed that dependent modules get loaded quickly from their .o's and thought that was handy, but that's all. During that time I have many times been annoyed that a .hs file which I load from the command line or via :load (or via C-c C-l in emacs mode) get loaded in interpreted form :) Jules ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ghc 6.8.1 bug?
I'm also seeing unusual behavior from GSL under ghc-6.8.1. I get a singular matrix error where there was none before, but if I prefix the function's rhs with m `seq`, where m is the matrix in question, the error goes away. I'll try removing the seq and compiling with -fvia-C tomorrow to see if I can confirm that that makes the problem go away too. Certain inputs cause it to fail repeatably, while others do not fail; I'm not seeing random behavior like Alberto is. Strange indeed. -- Joel ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell and html input elements
Hi What i have in mind is an interactive Haskell app which allows the user to enter text, push buttons, select radio buttons and so on. As I have already done a lot of xhtml coding I thought it might be easier to operate the program entirely via a web browser. However, I'm also interested in the idea of a straightahead MS Windows GUI for my program but dont' really know where to start. Any advice would be most appreciated. Cheers Paul At 17:13 12/11/2007, you wrote: On Nov 12, 2007, at 8:38 AM, PR Stanley wrote: Hi back again! How easy/hard is it to control a haskell program through a web browser? Hi, It depends on exactly how you want to control it, but at least some control is fairly easy. If you simply want to start a batch Haskell program, and see its output as HTML in a browser, you can use the cgi [1] or fastcgi [2] libraries listed on Hackage. If you want slightly more interactivity, it would make sense to write your Haskell program as its own web server (which is actually surprisingly easy) and have it respond to sequences of requests, perhaphs storing intermediate state along the way. Giving something like this a nice GUI on the user side will probably involve writing a certain amount of JavaScript. One example of a program that works this way is HERA [3], which is unfortunately not open-source at the moment, but may be some day. Another potentially useful library is HAppS [4], which abstracts out some of the functionality necessary for web-based applications. Is this sort of thing along the right track, or were you thinking of something else? Aaron [1] http://hackage.haskell.org/cgi-bin/hackage-scripts/package/ cgi-3001.1.5.1 [2] http://hackage.haskell.org/cgi-bin/hackage-scripts/package/ fastcgi-3001.0.1 [3] http://haskell.org/haskellwiki/ Haskell_Equational_Reasoning_Assistant [4] http://hackage.haskell.org/cgi-bin/hackage-scripts/package/ HAppS-0.8.4 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: List of all powers
Brent Yorgey wrote: apfelmus, does someone pay you to write so many thorough, insightful and well-explained analyses on haskell-cafe? I'm guessing the answer is 'no', but clearly someone should! =) Depending on length, my prices for posts range between λ9.99 and λ29.99 ;) Regards, apfelmus ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Weird ghci behaviour?
On Thu, 15 Nov 2007, Jules Bean wrote: Anecdotes have little value, but for what it's worth: in around 5 years of ghc use, I have never, not even once, wanted to load the module I was working on in its compiled form. I've occasionally noticed that dependent modules get loaded quickly from their .o's and thought that was handy, but that's all. During that time I have many times been annoyed that a .hs file which I load from the command line or via :load (or via C-c C-l in emacs mode) get loaded in interpreted form :) I found compiled modules useful in GHCi when using computation intensive functions, like those for signal processing. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re[2]: [Haskell-cafe] let vs. where
Hello Henning, Thursday, November 15, 2007, 2:31:07 PM, you wrote: Btw. I would write here min 1 (max (-1) x) or even better define a function for such clipping, since it is needed quite often. min 1 . max (-1) is pretty standard, although i renamed them: atMax 1 . atLeast (-1) -- Best regards, Bulatmailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re[2]: [Haskell-cafe] let vs. where
On Thu, 15 Nov 2007, Bulat Ziganshin wrote: Hello Henning, Thursday, November 15, 2007, 2:31:07 PM, you wrote: Btw. I would write here min 1 (max (-1) x) or even better define a function for such clipping, since it is needed quite often. min 1 . max (-1) is pretty standard, although i renamed them: atMax 1 . atLeast (-1) I like to add, that it is not just fancy to use functions instead of guards here. If you work with wrappers for software synthesizers like CSound and SuperCollider, you cannot map a Haskell function over a signal, say map (\x - case x of _ | x -1 - -1 | x1 - 1 | otherwise - x) signal but you can write Synth.min 1 $ Synth.max (-1) signal given that 'Synth.min' and 'Synth.max' call the pointwise minimum and maximum functions of the software synthesizers. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Flymake Haskell
On Nov 15, 2007 7:25 AM, Philip Armstrong [EMAIL PROTECTED] wrote: On Thu, Nov 15, 2007 at 02:56:32PM +0900, Daisuke IKEGAMI wrote: Dear Stefan and Haskell-Cafe, Thanks to keeping your interest to the flymake-mode for Haskell. Stefan wrote: Could you explain to me what flycheck_haskell.pl does, and give an example of a problematic situation solved by the use of flycheck_haskell.pl. Sure. I'll add in passing that fixing flymake to cope with multi-line errors was fairly simple obviates the need for the extra perl script. I can pass on patches if anyone cares. I care! -- Denis ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Weird ghci behaviour?
Jonathan Cast wrote: On 13 Nov 2007, at 11:03 PM, Jules Bean wrote: Just to be clear: my proposal is that if you want it to go faster you do ghci foo.hi or ghci foo.o ... so you still have the option to run on compiled code. My suggestion is simply that ghci foo.hs is an instruction to load source code (similarly :load); while ghci foo.o is obviously an instruction to load compiled code. Even just having :m + *Foo Currently :m doesn't load any modules, it just alters the context (what's in scope at the prompt), and fails if you ask for a module that isn't loaded. It would make sense for :m +M to behave like :add if M wasn't loaded, though. And perhaps :add *M or :load *M should ignore compiled code for M - that's another option. Cheers, Simon ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Haskell Job Opportunity
Hello, Eaton (eaton.com, Eden Prairie, MN US) is seeking software engineers for design and verification of electro-hydraulic control systems for industrial, automotive, and aerospace applications. Though I am still trying to get Haskell on the official job description, here are a few of the potential Haskell applications: - Domain specific languages. - Compiler design and embedded code generation. - Model checking and equivalence checking. - SAT decision procedures. - Constrained random simulation. - Software timing analysis. General knowledge of the following would be helpful: - Control theory. - Real-time, embedded programming. - Automotive and industrial systems. - Hydraulics and fluid power. If interested, send me a resume. Thanks! -Tom Hawkins ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ghc 6.8.1 bug?
Can any of you give us a testcase for this, please? Thanks Ian ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] let vs. where
On Thu, 15 Nov 2007 12:31:07 +0100, Henning Thielemann [EMAIL PROTECTED] wrote: On Tue, 13 Nov 2007, Dan Piponi wrote: On Nov 13, 2007 1:24 PM, Ryan Ingram [EMAIL PROTECTED] wrote: I tend to prefer where, but I think that guards function declarations are more readable than giant if-thens and case constructs. Up until yesterday I had presumed that guards only applied to functions. But I was poking about in the Random module and discovered that you can write things like a | x 1 = 1 | x -1 = -1 | otherwise = x Btw. I would write here min 1 (max (-1) x) or even better define a function for such clipping, since it is needed quite often. The value of 'a' needs only be calculated once; when defined at top level, 'a' is a CAF; in a 'where' clause, the value is also calculated once. -- Met vriendelijke groet, Henk-Jan van Tuyl -- http://functor.bamikanarie.com http://Van.Tuyl.eu/ -- ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Using Data.Binary for compression
On Wed, Nov 14, 2007 at 10:03:52PM -0800, Chad Scherrer wrote: I'd like to be able to use Data.Binary (or similar) for compression. Say I have an abstract type Symbol, and for each value of Symbol I have a representation in terms of some number of bits. For compression to be efficient, commonly-used Symbols should have very short representations, while less common ones can be longer. I agree with others that it's probably not worth your effort to do compression yourself except for fun, but it *is* fun, and interpret my advice below in that light. (Also, bitwise operations could be useful for other things, like interacting with standard formats. e.g. writing IEEE doubles portably, something that Data.Binary doesn't do.) ... (2) This seems like it will work ok, but the feel is not as clean as the current Data.Binary interface. Is there something I'm missing that might make it easier to integrate this? I would write this as a monad, analogous to PutM. Make bit monads GetBits and PutBitsM (with PutBits = PutBitsM ()), and then write functions like writeBits :: PutBits - Put readBits :: GetBits a - Get a where writeBits and readBits would pad their reading/writing to the next byte boundary (or perhaps Word32 boundary, for better performance?) as they must. So now this would have two main uses: users could use it to serialize data (e.g. writing an IEEE Double serialization), or could use it to write their own data compression, but putting *all* the serialization into the Bits level. This approach, of course, also would allow you to copy much of the infrastructure of Binary into your new bit-level interface. (3) Right now this is just proof of concept, but eventually I'd like to do some performance tuning, and it would be nice to have a representation that's amenable to this. Any thoughts on speeding this up while keeping the interface reasonably clean would be much appreciated. I think a monad as above would have the advantage of separating the implementation from the interface, which should make it tuneable. -- David Roundy Department of Physics Oregon State University ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Weird ghci behaviour?
It's worth saying that right now, all you have to do to get the source file loaded is :! touch M.hs :reload Put this in a macro, if you want: :def src \s - return (:! touch ++s) I hear the arguments in this thread, and others have suggested changes before: http://hackage.haskell.org/trac/ghc/ticket/1205 http://hackage.haskell.org/trac/ghc/ticket/1439 One of the suggestions was that if you name the source file rather than the module name, you get the source file loaded for that file, and any object code is ignored. So any files you explicitly want to have full top-level scope for must be named in :load or on the GHCi command line. The only problem with this is that someone who isn't aware of this convention might accidentally be ignoring compiled code, or might wonder why their compiled code isn't being used. Well, perhaps this is less confusing than the current behaviour; personally I find the current behaviour consistent and easy to understand, but I guess I'm in the minority! The other suggestion is to have a variant of :load that ignores compiled code (or for :load to do that by default, and rename the current :load to something else). I don't have a strong preference. Cheers, Simon Short form of my proposal: Make two separate commands that each have a predictable behavior. Make ghci modulename default to source loading, and require a flag to load a binary. I don't give a bikeshed what they are called. I don't care if the magic :load stays or goes or ends up with only one behavior. This is different/orthogonal to the .o or .hs file extension sensitive proposal. My arguments: I run into annoyances because I often poke at things in ghci when trying to get my package to compile. So depending on which modules succeeded or failed to compile I get different behavior when loading into ghci. I am no longer confused by this, but just annoyed. I would say that the user gets surprised which leads to feeling that there is a lack of control. The '*' in the '*Main' versus 'Main' prompt is a UI feature for experts, not for new users. Making this more obvious or verbose or better documented does not fix the lack of control the user feels. The only flags that the user can easily find are those listed by --help: chrisk$ ghci --help Usage: ghci [command-line-options-and-input-files] The kinds of input files that can be given on the command-line include: - Haskell source files (.hs or .lhs suffix) - Object files (.o suffix, or .obj on Windows) - Dynamic libraries (.so suffix, or .dll on Windows) In addition, ghci accepts most of the command-line options that plain GHC does. Some of the options that are commonly used are: -fglasgow-exts Allow Glasgow extensions (unboxed types, etc.) -idir Search for imported modules in the directory dir. -H32m Increase GHC's default heap size to 32m -cppEnable CPP processing of source files Full details can be found in the User's Guide, an online copy of which can be found here: http://www.haskell.org/ghc/documentation.html The -fforce-recomp and -fno-force-recomp flags only exist in the User's Guide. Thus they are hard to find. Is there a ticket open for adding at least a list of the recognized flags to ghc and ghci usage messages? Ideally, I want a :load modulename to get the source and a :bin modulename to get the binary (and a :m ... to get the binary). I want ghci modulename to get the source and ghch -bin modulename to get the binary. Simple and predictable and no surprises. Cheers, Chris K ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] cabal Main-Is restriction
On Thu, 2007-11-15 at 11:14 -0600, Nicolas Frisby wrote: It seems the meaning of the -main-is switch for GHC and the Main-Is build option for Cabal executables differ. With GHC, I can point to any function main in any module, but in Cabal I must point to a filename with precisely the module name Main. This is tying my hands with regard to organizing a default executable and exposing some of its functionality as a library. Is there a way to get around this restriction? I've filed your feature request in the Cabal trac: http://hackage.haskell.org/trac/hackage/ticket/179 Do please add your suggestions in a comment there. Login with username guest and password haskell' (note the apostrophe at the end). Is this currently possible? I recognize the add a separate Program-Main.hs file workaround, but I'll avoid it if I can. A workaround is to use: main-is: Program/Main.hs ghc-options: -main-is Program.Main Duncan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ghc 6.8.1 bug?
Alberto Ruiz-2 wrote: Hello, I have had exactly the same problem with my bindings to GSL, BLAS and LAPACK. The foreign functions (!) randomly (but very frequently) produced NaN with ghc-6.8.1 -O. As usual, I first thought that I had a subtle bug related to the foreign pointers, but after a lot of refactoring, experiments, and tracing everything, I'm reasonably sure that memory is safely used. What I have found is that the same errors can be reproduced on ghc-6.6.1 with -O -fasm. So I tried -O -fvia-C on ghc-6.8.1 (which now it is not the default) and apparently everything works well. So it seems that now the ffi requires and additional and explicit -fvia-C. In any case I don't know why -fasm produces those strange NaN in precompiled foreign functions... Alberto Arrgh, the fix of using -fvia-C doesn't seem to be working for me. You got my hopes up for a moment :). I also am calling BLAS via C bindings. I am going to try to distill my case down to the bare minimum if possible and then provide an example. It may take a while. -- View this message in context: http://www.nabble.com/ghc-6.8.1-bug--tf4810375.html#a13779349 Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskellforge?
duncan.coutts: On Thu, 2007-11-15 at 15:56 -0200, Maurício wrote: Hi, Is there a Haskellforge somewhere, i.e., something like a sourceforge for open source Haskell programs, with darcs, automatic cabalization etc.? Has anyone tried that already? There is the Haskell Community server http://community.haskell.org/ It hosts darcs repos at http://code.haskell.org/ You can request an account and projects via: http://community.haskell.org/admin/ There are currently 44 registered developers and 41 hosted projects. It may host more services in future, like bug trackers. lambdabot is hosted there too, now. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Vertigo / GHC / Memo
Hi Haskell Lovers,
Im trying to compile Vertigo (http://conal.net/Vertigo), which seems to be
a module from which I can really learn a lot of stuff.
However, it seems to use a Memo module, which does not seem to be part of
GHC (anymore?) As far as I understand, it uses a memo function to make sure
that when performing symbolic differentiation, it does not get stuck in an
endless loop.
As I realize no generic memoization function can be made, I guess it got
removed at some point?
Can anyone give me a hint how to find a suitable Memo module for Vertigo?
As a sidenote, I must say the memoization section on Haskell.org is not
really helpful for a newbie like me...
Thanks,
Peter
PS: I adapted the following code from SOE, but I'm not sure it does the job
correctly (it will certainly be slow...)
{-# OPTIONS_GHC -fglasgow-exts #-}
module Memo(memo) where
import Data.IORef
import System.IO.Unsafe
memo :: Eq a = (a-b) - (a-b)
memo f = unsafePerformIO $ do
cache - newIORef []
return $ \x -
unsafePerformIO $ do
vals - readIORef cache
case x `inCache` vals of
Nothing - do
let y = f x
modifyIORef cache ((x,y):)
return y
Just y - do
return y
inCache :: Eq a = a - [(a,b)] - Maybe b
x `inCache` [] = Nothing
x `inCache` ((x',y'):xys) =
if x == x'
then Just y'
else x `inCache` xys
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Re: [Haskell-cafe] HTTP actions proxy server
On Nov 15, 2007 9:01 AM, Jim Burton [EMAIL PROTECTED] wrote: How would I go about converting the little get program at http://darcs.haskell.org/http/test/get.hs to use a proxy server? I tried adding a call to setProxy like this but it doesn't work: I think it needs to be a real URL: setProxy (Proxy http://myproxy:80; Nothing) Justin ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ghc 6.8.1 bug?
Alberto Ruiz-2 wrote: Hmm, I' sorry... all seems to work well for me if I set -O -fvia-C for building the library and for final program compilation. But I will also try to find a minimum test case. In the meantime I have sent to Ian information to expose the problem with my library, although I know that such large amount of code will not be very helpful. Have you tested ghc-6.6.1 with -O -fasm? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe Good idea. I just tried that. However, it worked just fine even with -fasm in ghc 6.6.1. One thought that I had as well was to be sure to recompile my C code that interfaces to Haskell using the HsFFI.h header from 6.8.1 instead of 6.6.1 just in case something might have changed. Unfortunately in my case it made no difference. -- View this message in context: http://www.nabble.com/ghc-6.8.1-bug--tf4810375.html#a13781878 Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Chart plotting libraries
On Wed, Nov 14, 2007 at 10:36:06PM -0800, Don Stewart wrote: jon: I'd like some free software to help me plot charts like the one from the ray tracer language comparison: http://www.ffconsultancy.com/languages/ray_tracer/results.html I was using Mathematica but its stopped working and an upgrade is £2,000. Are there Haskell bindings to any free libraries or even Haskell implementations that would make something like this painless? There isn't anything for OCaml (that I'm not still writing ;-) so this might be a good opportunity to force me to do a little more Haskell. :-) A quick search of hackage.haskell.org, http://hackage.haskell.org/cgi-bin/hackage-scripts/package/Chart-2007.8.8 Using gtk and cairo. Homepage here: http://dockerz.net/twd/HaskellCharts Chart has rather a complicated API. I've written a simpler API (but somewhat less flexible), if anyone's interested (Tim wasn't). My API is closer in complexity (of use) to matlab's plotting. -- David Roundy Department of Physics Oregon State University ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ghc 6.8.1 bug?
On Thursday 15 November 2007 19:58, SevenThunders wrote: Alberto Ruiz-2 wrote: Hello, I have had exactly the same problem with my bindings to GSL, BLAS and LAPACK. The foreign functions (!) randomly (but very frequently) produced NaN with ghc-6.8.1 -O. As usual, I first thought that I had a subtle bug related to the foreign pointers, but after a lot of refactoring, experiments, and tracing everything, I'm reasonably sure that memory is safely used. What I have found is that the same errors can be reproduced on ghc-6.6.1 with -O -fasm. So I tried -O -fvia-C on ghc-6.8.1 (which now it is not the default) and apparently everything works well. So it seems that now the ffi requires and additional and explicit -fvia-C. In any case I don't know why -fasm produces those strange NaN in precompiled foreign functions... Alberto Arrgh, the fix of using -fvia-C doesn't seem to be working for me. You got my hopes up for a moment :). I also am calling BLAS via C bindings. I am going to try to distill my case down to the bare minimum if possible and then provide an example. It may take a while. Hmm, I' sorry... all seems to work well for me if I set -O -fvia-C for building the library and for final program compilation. But I will also try to find a minimum test case. In the meantime I have sent to Ian information to expose the problem with my library, although I know that such large amount of code will not be very helpful. Have you tested ghc-6.6.1 with -O -fasm? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] dropSpace not exported in ByteString
olivier.boudry: Hi all, I'm writing a Haskell program to do some address cleansing. The program uses the ByteString library. Data.ByteString.Char8 documentations shows functions for removing whitespace from start or end of a ByteString. Those functions are said to be more efficient than the dropWhile / reverse mixes. It looks exactly like what I'm searching for, but apparently those functions are not exported by the Data.ByteString.Char8 module. Are those functions only called by rules? Transformation of dropWhile isSpace into dropSpace? I've seen such a rule for dropSpace but did not found an equivalent rule for dropSpaceEnd. Is there a way to call the dropSpace and dropSpaceEnd or do I have to code with dropWhile and hope that some rule will magically transform my dropWhileS into dropSpaceS? The latter: FPS specialise dropWhile isSpace - dropSpace dropWhile isSpace = dropSpace check that the rule fires with -ddump-simpl-stats There's no rule for dropSpaceEnd, but you can certainly inline the defn in your code, if perf. matters. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] dropSpace not exported in ByteString
Hi Don, In fact I'm not really looking at performance, I don't expect performance to be a big issue in my application. I was just looking at using some simple functions found in the documentation and avoid redefining them. In fact dropSpace and dropSpaceEnd are doing exactly what I'm looking for. But of course if they're not exported it's not a problem and I'll use their dropWhile equivalent. Thanks for your reply, Olivier. On Nov 15, 2007 5:24 PM, Don Stewart [EMAIL PROTECTED] wrote: The latter: FPS specialise dropWhile isSpace - dropSpace dropWhile isSpace = dropSpace check that the rule fires with -ddump-simpl-stats There's no rule for dropSpaceEnd, but you can certainly inline the defn in your code, if perf. matters. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] dropSpace not exported in ByteString
olivier.boudry: Hi Don, In fact I'm not really looking at performance, I don't expect performance to be a big issue in my application. I was just looking at using some simple functions found in the documentation and avoid redefining them. In fact dropSpace and dropSpaceEnd are doing exactly what I'm looking for. But of course if they're not exported it's not a problem and I'll use their dropWhile equivalent. Thanks for your reply, Let me know if the rule fires. If it isn't, that's a bug, essentially. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] (general question) Approaches for storing large amount of simple data structures
I have a project where I want to store a data structure on a file, binary or ascii. And I want to use haskell to read and write the file. I will have about half a million records so it would be nice if the format was able to load quickly. I guess I could, but I kind of want to avoid using XML. I have the following structure in pseudo code. A URL - id - keywords associated with that URL - title associated with that URL - links contained in that URL. (0 ... N) What is an approach for saving 500 thousand of those types of records and where I can load the data into a haskell data type. -- Berlin Brown [berlin dot brown at gmail dot com] http://botspiritcompany.com/botlist/? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] (general question) Approaches for storing large amount of simple data structures
bbrown: I have a project where I want to store a data structure on a file, binary or ascii. And I want to use haskell to read and write the file. I will have about half a million records so it would be nice if the format was able to load quickly. I guess I could, but I kind of want to avoid using XML. I have the following structure in pseudo code. - keywords associated with that URL - title associated with that URL - links contained in that URL. (0 ... N) What is an approach for saving 500 thousand of those types of records and where I can load the data into a haskell data type. Data.Binary is the standard approach for large data/high performance serialising to and from Haskell types. It composes well with the gzip librarry too, so you can compress the stream on the way out, and decompress lazily on the way in. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/binary-0.4.1 The interface is really simple: encode :: Binary a = a - ByteString decode :: Binary a = ByteString - a For marshalling Haskell type 'a' into a bytestring and back. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] let vs. where
On Nov 16, 2007 12:35 AM, Arnar Birgisson [EMAIL PROTECTED] wrote: [1] I'm terribly sorry, that was meant to be: [1] http://www.onlamp.com/pub/a/onlamp/2007/07/12/introduction-to-haskell-pure-functions.html sorry, Arnar ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Chart plotting libraries
On Nov 15, 2007 10:33 AM, David Roundy [EMAIL PROTECTED] wrote: Chart has rather a complicated API. I've written a simpler API (but somewhat less flexible), if anyone's interested (Tim wasn't). My API is closer in complexity (of use) to matlab's plotting. I'd be interested, for one. Cheers, Graham Graham Fawcett Centre for Teaching and Learning University of Windsor ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] ghc 6.8.1 bug?
The good news is that my code compiles without error and much faster under ghc 6.8.1. The bad news is that there appear to be subtle bugs that did not occur when I compiled things under 6.6.1. One issue is that my code is somewhat complex and links into a C library as well. The new behavior is that under certain conditions a certain matrix inner product produces undefined floats, that should not be there. If the code is executed inside any function it fails but if the same code is reexecuted at the ghci prompt it works. Here is the gist of the code that I'm running main = do ... lots of computations and let clauses -- get a submatrix viewMatbotk wstart nsua su 1 suw -- get another submatrix viewMatbotk 0 nsua arrstart npaths sua -- complex non conjugated inner product (multiply the two submatrices) mulCFtF mprint If this is executed either in ghci as main or from a Dos prompt I get a matrix filled with bad values including a few that look like -1.#IND+1.87514i If I recompile everything in ghc-6.6.1 it works like charm. I make sure that I have deleted all the .o and .hi files. There is a dll that contains a C library I link to via running dlltool.exe. If I print out all the function inputs to the function viewMatbotk and then call them interactively in ghc 6.8.1 and call mulCFtF interactively it works correctly. both viewMatbotk and mulCFtF are C routines pulled in from the external library. I am at a complete loss how to debug this or how to pin down what exactly has changed between 6.6.1 and 6.8.1 that breaks this code so badly. This type of error stinks of some kind of memory issue, e.g. corrupted pointers. Any suggestions would be appreciated. Unfortunately the code base is rather involved and potentially proprietary so I can't publish all of the details. -- View this message in context: http://www.nabble.com/ghc-6.8.1-bug--tf4810375.html#a13763341 Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Asynchronous exceptions and the RealWorld
- I want to set timeouts on various IO operations in an existing library, ftphs. However, even if I wrap every call in `block`, it's unclear whether ftphs has been coded to deal with asynchronous exceptions, or whether state could be rendered inconsistent. Is there any solution for this aside from auditing/changing ftphs? - I can't find any documentation on which calls are (either directly or indirectly, or parametrically) interruptible operations (to use the term from the Async Exceptions paper). For instance, I experimentally determined that hPutStrLn on a socket is *not*. Does such documentation exist anywhere? Furthermore, is there any way to embed this information in the type system, so that Haskellers don't produce async-exception-unaware code? (Effectively, introducing checked interrupts?) - The above finding of hPutStrLn (as an example) is somewhat surprising, since the socket buffer may be full, causing the call to block indefinitely. We can unblock that call, but unless there's a way to atomically reinstate the block and save the result of the computation (the unit value), this effectively makes it impossible to determine whether the hPutStrLn returned. (Admittedly, this is a contrived example, since whether a call to hPutStrLn returns is usually not a useful result - but this is the first thing I tried, and I'm guessing there are more such IO operations that actually yield useful results.) - Are there any higher-level concurrency libraries that actually tackle these hand-in-hand issues (safe asynchronous interruptible IO, two-phase-commit to prevent dropping results, choice, etc.)? I tried searching for a while, coming up with PiMonad, HAppS.Util, MissingH.Threads.Timeout, but none of them really address these issues. Perhaps this is just impossible in Concurrent Haskell, and one would need to resort to the sure-fire home-rolled solution using delimited continuations and cooperative scheduling for any serious concurrency abstractions for systems programming. Thanks in advance for any answers! ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] HTTP actions proxy server
How would I go about converting the little get program at http://darcs.haskell.org/http/test/get.hs to use a proxy server? I tried adding a call to setProxy like this but it doesn't work: get :: URI - IO String get uri = do browse $ setProxy (Proxy myproxy:80 Nothing) eresp - simpleHTTP (request uri) resp - handleE (err . show) eresp case rspCode resp of (2,0,0) - return (rspBody resp) _ - err (httpError resp) where showRspCode (a,b,c) = map intToDigit [a,b,c] httpError resp = showRspCode (rspCode resp) ++ ++ rspReason resp Thanks. -- View this message in context: http://www.nabble.com/HTTP-actions---proxy-server-tf4815272.html#a13775608 Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskellforge?
On Thu, 2007-11-15 at 15:56 -0200, Maurício wrote: Hi, Is there a Haskellforge somewhere, i.e., something like a sourceforge for open source Haskell programs, with darcs, automatic cabalization etc.? Has anyone tried that already? There is the Haskell Community server http://community.haskell.org/ It hosts darcs repos at http://code.haskell.org/ You can request an account and projects via: http://community.haskell.org/admin/ There are currently 44 registered developers and 41 hosted projects. It may host more services in future, like bug trackers. Duncan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] A small question
http://msdn2.microsoft.com/en-us/library/1w45z383(vs.71).aspx I believe. /g On Nov 15, 2007 12:56 PM, Andrew Coppin [EMAIL PROTECTED] wrote: I notice that in GHC 6.8.1, if I compile a runnably program, as well as generating foo.exe, GHC now also generates a file foo.exe.manifest, which appears to contain some kind of XML data. Anybody know anything about this mysterious file? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- The man who'd introduced them didn't much like either of them, though he acted as if he did, anxious as he was to preserve good relations at all times. One never knew, after all, now did one now did one now did one. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Erik Meijer's talk at Google?
Hello, Last week (?) Erik Meijer gave a talk at Google. Has a video been uploaded somewhere? Kind regards, Vasya ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] dropSpace not exported in ByteString
olivier.boudry: On 11/15/07, Don Stewart [EMAIL PROTECTED] wrote: Let me know if the rule fires. If it isn't, that's a bug, essentially. -- Don Don, As you can see the rule fires. C:\Tempghc --make -O2 -fasm -ddump-simpl-stats DropSpaceTest.hs ... 3 RuleFired 1 FPS pack/packAddress 2 FPS specialise dropWhile isSpace - dropSpace ... Great! The first rule is also a good sign. By the way, what's the reason dropSpaceEnd is defined but not exported nor used through a rule? I'm just curious. Looking at the source, its not actually defined -- its commented out. Perhaps you're looking at an older version of the source? -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] let vs. where
No, Haskell functions take exactly one argument. On Nov 14, 2007 1:05 AM, Robin Green [EMAIL PROTECTED] wrote: On Tue, 13 Nov 2007 13:51:13 -0800 Dan Piponi [EMAIL PROTECTED] wrote: Up until yesterday I had presumed that guards only applied to functions. But I was poking about in the Random module and discovered that you can write things like a | x 1 = 1 | x -1 = -1 | otherwise = x where 'a' clearly isn't a function. Isn't it a function taking zero arguments? -- Robin ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Flymake Haskell
On Thu, Nov 15, 2007 at 09:19:10AM -0500, Denis Bueno wrote: On Nov 15, 2007 7:25 AM, Philip Armstrong [EMAIL PROTECTED] wrote: I can pass on patches if anyone cares. I care! Will dig them out asap then! Phil -- http://www.kantaka.co.uk/ .oOo. public key: http://www.kantaka.co.uk/gpg.txt ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Chart plotting libraries
droundy: Chart has rather a complicated API. I've written a simpler API (but somewhat less flexible), if anyone's interested (Tim wasn't). My API is closer in complexity (of use) to matlab's plotting. I'd describe the API as verbose rather than complicated. It takes 5-10 lines of haskell to define a chart - see the examples on the web page. I think this is fine for use within other code, but I agree is too much typing for interactive use. Tim ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] the interact function and Hugs/ghci on Windows ...
Hello, I have a Haskell script that contains several functions that are implemented in terms on interact. When I do a function application, Hugs/ghci is waiting for input from stdin. How do one denote EOF from stdin, so that the function evaluation can continue and do the IO () action , ie.. write to stdout? Regards, Vasili ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Performance problems with parallelizing QuickCheck using channels (Control.Concurrent.Chan)
So I've been trying to get my QuickCheck tests to run in parallel. I did take a
look at Don's Parallel QuickCheck library
http://www.cse.unsw.edu.au/~dons/pqc.html, but I didn't like how much code it
had in it and I figured it'd be a good exercise to try to do myself.
After quite a lot of help from the good folk of #haskell, I eventually came up
with this:
module Pcheck (parTest, parCheck) where
import Control.Monad (replicateM_, liftM)
import Control.Concurrent.Chan (newChan, writeChan, getChanContents)
import Control.Concurrent (forkIO)
import Test.QuickCheck (quickCheck', Testable())
-- | Takes a list of functions using parCheck, and returns True iff all return
-- True. Evaluates them in parallel.
parTest :: [IO Bool] - IO Bool
parTest = andTest . parList
where andTest :: IO [Bool] - IO Bool
andTest = liftM and
{- | Test in parallel. Forks off a QuickCheck 'n' times; QuickCheck tests
using
the proposition 't'. Returns True if all tests were passed, else
False. Should be run with parallelizing options like with +RTS -N4 -RTS
etc. -}
parCheck :: (Testable prop) = prop - Int - IO Bool
parCheck t n = do chan - newChan
replicateM_ n $ forkIO $ (writeChan chan) = (quickCheck'
t)
liftM (and . take n) $ getChanContents chan
-- | Takes a list of functions (presumably using parCheck) and evaluates all
in parallel.
parList :: [IO a] - IO [a]
parList fs = do chan - newChan
mapM_ (\m - forkIO $ m = writeChan chan) fs
liftM (take n) $ getChanContents chan
where n = length fs
I liked how simple the Channels library
http://haskell.org/ghc/docs/latest/html/libraries/base-3.0.0.0/Control-Concurrent-Chan.html
seemed to be; I could just pass the channel as an argument and have every
forkIO'd test simply chuck its Boolean result into it when done - which seem'd
much simpler than using MVars and the other techniques for returning stuff from
forkIO threads.
And so it compiles, it runs tests correctly, and so on. But the problem is that
it does so slowly. I have another module of equations about nuclear bombs
called nuke.hs, which has a number of QuickCheck properties defined. Here's
what happens when main is defined as 'parTest [the various tests..]':
./nuke +RTS -N7 -sstderr -RTS 40.57s user 46.55s system 116% cpu 1:14.61 total
./nuke +RTS -N6 -sstderr -RTS 40.72s user 47.66s system 117% cpu 1:15.50 total
./nuke +RTS -N5 -sstderr -RTS 42.33s user 49.08s system 116% cpu 1:18.67 total
./nuke +RTS -N4 -sstderr -RTS 43.71s user 48.41s system 117% cpu 1:18.48 total
./nuke +RTS -N3 -sstderr -RTS 41.51s user 48.25s system 114% cpu 1:18.10 total
./nuke +RTS -N2 -sstderr -RTS 42.28s user 47.18s system 115% cpu 1:17.39 total
./nuke +RTS -N1 -sstderr -RTS 27.87s user 18.40s system 99% cpu 46.498 total
(From http://hpaste.org/3886#a6; compiled as =ghc -v --make -threaded -O2
./nuke.hs.)
For some reason, running the parallel tests with a single thread is faster than
running with 4 threads (I have a quad-core Intel processor)? I find this
counter-intuitive to say the least. the par* functions are indeed operating in
parallel, as evidenced by it using more than 100% CPU time, or, running on
multiple cores, and all the tests are passed as True in both -N1 and -N[2-7]
versions, so -N1 can't be bailing out early due to and's laziness, and in
general everything seems to be written correctly.
I am perplexed by this. Is Chan simply a very inefficient way of parallelizing
things? Is it not as parallel as I think? Or am I missing something else
entirely?
(Attached is the source of nuke.hs and pcheck.hs, as well as some data from
-sstderr.)
--
gwern
.45 GIGN jya. wire ISI SADCC JPL embassy Recon World
-- module Nuke (main)
-- where
-- TODO: work in radiation deaths.
import Pcheck
import Test.QuickCheck
import Monad (liftM3)
{- For many equations and results, it is nonsensical to have negative results, but we don't want
to use solely natural numbers because then we lose precision. So we define a PosReal type which tries
to define the subset of real numbers which are 0 or positive; this way the type system checks for negative
results instead of every other function having conditionals checking for negative input or output. -}
newtype PosReal = MakePosReal Float deriving (Show, Eq, Ord)
-- Basic numerical operations on positive reals
instance Num PosReal where
fromInteger = toPosReal . fromInteger
x + y = MakePosReal (fromPosReal x + fromPosReal y)
x - y = toPosReal ((fromPosReal x) - (fromPosReal y))
x * y = MakePosReal (fromPosReal x * fromPosReal y)
abs x | x = 0 = x
| otherwise = x * (-1)
signum x | x = 0 = 1
| otherwise = (-1)
-- Define division on PosReals
instance Fractional PosReal where
x / y = toPosReal ((fromPosReal x) / (fromPosReal y))
fromRational x = MakePosReal (fromRational x)
RE: [Haskell-cafe] Erik Meijer's talk at Google?
I think google talks are often hosted at video.google.com, assuming the speaker agrees to this and it can be publicly disclosed. -- Anwar Ghuloum 葛安华 Microprocessor Technology Lab, Intel _ From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] org] On Behalf Of Galchin Vasili Sent: Thursday, November 15, 2007 7:39 PM To: haskell-cafe@haskell.org Cc: Galchin Vasili Subject: [Haskell-cafe] Erik Meijer's talk at Google? Hello, Last week (?) Erik Meijer gave a talk at Google. Has a video been uploaded somewhere? Kind regards, Vasya smime.p7s Description: S/MIME cryptographic signature ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] the interact function and Hugs/ghci on Windows ...
On Nov 15, 2007 6:25 PM, Galchin Vasili [EMAIL PROTECTED] wrote: Hello, I have a Haskell script that contains several functions that are implemented in terms on interact. When I do a function application, Hugs/ghci is waiting for input from stdin. How do one denote EOF from stdin, so that the function evaluation can continue and do the IO () action , ie.. write to stdout? Usually CTRL-D or CTRL-Z. Justin ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Haskellforge?
Hi, Is there a Haskellforge somewhere, i.e., something like a sourceforge for open source Haskell programs, with darcs, automatic cabalization etc.? Has anyone tried that already? Maurício ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Using Data.Binary for compression
On Thu, Nov 15, 2007 at 11:10:01AM -0800, Chad Scherrer wrote: Almost all 'real users' just use Codec.Compression.GZip. It's very fast, very compositional, and (perhaps suprisingly) almost as effective as application-specific schemes. I was about to say the same thing. So so much simpler to use Duncan's carefully written zlib binding, I have several types of symbols, and for each type the probabilities are very predictable - to the point where they could even be hard-coded. And upon completion I can be sure the first two questions will be Can we make it smaller? and Can we make it faster?. GZip (while very cool) is adaptive and general-purpose, so it's building frequency tables as it goes and ignoring the structure of the data I should be able to take advantage of. With an awful lot of trouble, it must be possible to write something in C to go faster and yield better compression than gzip for this particular data. With the probability structure known in advance, there are just a lot of steps taken by gzip that are no longer needed. Besides this, gzip only assumes an arbitrary sequence of bytes, but my data are much more structured than this. The catch is that gzip can beat even ideal arithmetic compression, if there happen to be correlations between symbols. So what you claim is correct only if there are no correlations other than those taken into account in your known probability structure. Any chance you can tell us what this mysterious data is? But bit stream operations (and data compression) are seriously cool in any case, so I hope you'll go ahead with this! -- David Roundy Department of Physics Oregon State University ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Guidance on using asynchronous exceptions
To follow up on my previous post (Asynchronous Exceptions and the RealWorld), I've decided to put together something more concrete in the hopes of eliciting response. I'm trying to write a library of higher-level concurrency abstractions, in particular for asynchronous systems programming. The principal goal here is composability and safety. Ideally, one can apply combinators on any existing (IO a), not just procedures written for this library. But that seems like a pipe dream at this point. In the code below, the running theme is process orchestration. (I've put TODOs at places where I'm blocked - no pun intended.) I'm currently worried that what I'm trying to do is simply impossible in Concurrent Haskell. I'm bewildered by the design decisions in the asynchronous exceptions paper. I'm also wondering if there are any efforts under way to reform this situation. I found some relevant posts below hinting at this, but I'm not sure what the status is today. (Something like this is straightforward to build if I abandon Concurrent Haskell and use cooperative threading, and if the operations I wanted to perform could be done asynchronously.) Relevant papers --- http://citeseer.ist.psu.edu/415348.html http://research.microsoft.com/users/simonpj/papers/concurrent-haskell.ps.gz http://www.haskell.org/~simonmar/papers/web-server.ps.gz Relevant posts/threads -- http://osdir.com/ml/lang.haskell.prime/2006-04/msg00032.html http://osdir.com/ml/lang.haskell.general/2001-11/msg00131.html http://www.haskell.org/pipermail/haskell-prime/2006-April/001280.html http://www.haskell.org/pipermail/haskell-prime/2006-April/001290.html http://www.nabble.com/throwTo---block-statements-considered-harmful-tf2780268.html#a7758038 http://www.nabble.com/What-guarantees-(if-any)-do-interruptible-operations-have-in-presence-of-asynchronous-exceptions--tf2761696.html#a7699555 Misc http://lambda-the-ultimate.org/node/1570 Advanced Exception Handling Mechanisms http://www.springerlink.com/content/3723wg2t81248027/ http://64.233.169.104/search?q=cache:c4pS0FDKMXcJ:www.cs.ioc.ee/tfp-icfp-gpce05/tfp-proc/06num.pdf+concurrency+interrupts+abort+safe+asynchronous+exceptions+threadsh http://64.233.169.104/search?q=cache:hmC-jl-iNkoJ:www.jot.fm/issues/issue_2007_11/article4.pdf+concurrency+interrupts+abort+safe+asynchronous+exceptions+threadshl=en http://www.mathematik.uni-marburg.de/~eden/paper/edenEuropar03.pdf Code module Main where import Control.Concurrent import Control.Concurrent.MVar import Control.Exception import Control.Monad import Prelude hiding (log) import System.IO import System.Posix.Signals import System.Process log = putStrLn startProc cmd = runCommand cmd stopProc p = terminateProcess p waitProc p = waitForProcess p -- Run a process, blocking on it until it exits. If we're interrupted, -- terminate the process. (IIRC, terminateProcess issues SIGTERM, and -- the documentation is buggy; more detailed code should go here later -- to retry with SIGKILL.) runProc cmd = do log launching proc p - startProc cmd waitProc p-- TODO allow interrupts only at this point `finally` ( log stopping stopProc p log stopped ) -- Sleep for n seconds. timeout n = do log sleeping threadDelay (n * 100) -- TODO allow interrupts only at this point log waking -- TODO is there any way to block *only* the Cancel exception? (Even -- if this could be done, though, it's still not a modular approach.) spawn :: IO a - (a - IO ()) - IO ThreadId spawn f y = forkIO (block (f = y)) -- The any/sum/choice combinator. On return, guarantee that both tasks -- have stopped. (|) :: IO a - IO b - IO (Either a b) a | b = do result - newEmptyMVar :: IO (MVar (Either a b)) tida - newEmptyMVar :: IO (MVar ThreadId) tidb - newEmptyMVar :: IO (MVar ThreadId) let yield lr x = do let name = case lr x of Left _ - a Right _ - b log $ saving result of ++ name putMVar result (lr x) log $ saved result of ++ name let other = case lr x of Left _ - tidb Right _ - tida log taking other t - takeMVar other log killing other -- Later: replace the following with a throwTo -- so as to notify (rather than kill) the thread -- with a Cancel killThread t ta - spawn a (yield Left) tb - spawn b (yield Right) putMVar tida ta putMVar tidb tb log waiting for result res - takeMVar result -- TODO wait for both tasks to have stopped log returning result return res -- simple test -- cmd1 = for i in `seq 1`; do sleep 1; echo hello; done cmd2 = for i in `seq 3`; do sleep 1; echo world;
