[Haskell-cafe] Re: [Haskell] ANN: Hipmunk 0.1 and HipmunkPlayground 0.1
On Sun, Jul 27, 2008 at 12:34 AM, Felipe Lessa [EMAIL PROTECTED] wrote: On Sun, Jul 27, 2008 at 12:29 AM, Antoine Latter [EMAIL PROTECTED] wrote: I'm getting the following error trying to cabal-install HipmunkPlayground: [duplicate symbol _deRefStablePtr] Well, I guess this isn't a random problem then. I had this in one of the Linux boxes but the first thing I tried to solve it worked so dismissed it as something not so important. Now dons had this problem as well. I've filled a GHC ticket at http://hackage.haskell.org/trac/ghc/ticket/2469 . Thanks, -- Felipe. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] ANN: Yi 0.4.1
I'm very pleased to announce the 0.4.1 release of the Yi editor. == Yi == Yi is a text editor written and extensible in Haskell. The long-term goal of the Yi project is to provide the editor of choice for Haskell programmers. In the meantime, we have fun by hacking an editor in a decent language :) Yi is not a finished product. This is an alpha-quality release. However, Yi has become a lot more accessible than previously, so if you feel like testing it, now might be a good time to take a look. == Installation == Using cabal install: cabal install yi-0.4.1 If you want gtk support, first install gtk2hs 0.9.13. If you want vty support, pass the -fvty option to cabal install. == Features == * A purely functional editor core; * Key-bindings written as parsers of the input; * Emacs, Vim and (partial) Cua emulations provided by default; * Vty, Gtk2Hs, and (experimental) Cocoa front-ends; * Static configuration (XMonad style) for fast load; * Simple Haskell support: * Syntax highlighting * Auto-indentation * Call cabal-build within the editor == Links == * download: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/yi * FAQ: http://haskell.org/haskellwiki/Yi/FAQ * homepage: http://haskell.org/haskellwiki/Yi * check and report issues: http://code.google.com/p/yi-editor/issues/list * darcs repository: http://code.haskell.org/yi * get involved: mailto:[EMAIL PROTECTED] * release notes: http://code.google.com/p/yi-editor/wiki/ReleaseNotes0o4 == Acks == This release is brought to you by: Allan Clark Andrew Birkett Corey O'Connor Duncan Coutts Evan Martin Fraser Wilson Gustav Munkby Gwern Branwen Jean-Philippe Bernardy Krasimr Angelov Nicolas Pouillard Sean Leather Thomas Schilling and all the contributors to the previous versions. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] library for zip compression?
Haskellers, Is there a library for compressing and uncompressing zip archives? I see zlib and bzlib on HackageDB, but unless I'm mistaken these won't help with a .zip archive. (See http://zlib.net/zlib_faq.html#faq11.) Any help here would be appreciated. John ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [HOpenGL] Re: [Haskell-cafe] Fw: patch applied (ghc): Remove the OpenGL familyof libraries fromextralibs
There is a section Projects using the OpenGL bindings (http://www.haskell.org/haskellwiki/OpenGL) on the wiki that is pretty bare. A quick search of HCAR lists five projects using OpenGL. --L On Sat, 26 Jul 2008, Jefferson Heard wrote: It would be nice to know, though, how many people are using it and what they're using it for. I'm using it for information visualization, and slowly evolving/cribbing together something like the Processing (http://www.processing.org) framework for Haskell as I do more things. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Exceptions
Hello, I think it'd be nice if the compiler could warn me if there are any exceptions which I'm not catching, similar to checked exceptions in Java. Does anyone know of a possibility to do that in Haskell? Adrian PGP.sig Description: Signierter Teil der Nachricht ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Exceptions
I don't really think this is possible: consider asynchronous exceptions and throwTo. http://www.haskell.org/ghc/docs/latest/html/libraries/base/Control-Exception.html#v%3AthrowTo Since it can throw just *any* exception into thread. And this thread might not be aware that anyone can throw him anything. Therefore it is not possible to catch it while compiling it's code. But Maybe I'm Just wrong. Christopher Skrzętnicki 2008/7/27 Adrian Neumann [EMAIL PROTECTED]: Hello, I think it'd be nice if the compiler could warn me if there are any exceptions which I'm not catching, similar to checked exceptions in Java. Does anyone know of a possibility to do that in Haskell? Adrian ___ 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] ANN: Yi 0.4.1
Fantastic release, thank you! It's never been so easy to start playing with Yi. : ) Paulo On Sun, Jul 27, 2008 at 10:08 AM, Jean-Philippe Bernardy [EMAIL PROTECTED] wrote: I'm very pleased to announce the 0.4.1 release of the Yi editor. == Yi == Yi is a text editor written and extensible in Haskell. The long-term goal of the Yi project is to provide the editor of choice for Haskell programmers. In the meantime, we have fun by hacking an editor in a decent language :) Yi is not a finished product. This is an alpha-quality release. However, Yi has become a lot more accessible than previously, so if you feel like testing it, now might be a good time to take a look. == Installation == Using cabal install: cabal install yi-0.4.1 If you want gtk support, first install gtk2hs 0.9.13. If you want vty support, pass the -fvty option to cabal install. == Features == * A purely functional editor core; * Key-bindings written as parsers of the input; * Emacs, Vim and (partial) Cua emulations provided by default; * Vty, Gtk2Hs, and (experimental) Cocoa front-ends; * Static configuration (XMonad style) for fast load; * Simple Haskell support: * Syntax highlighting * Auto-indentation * Call cabal-build within the editor == Links == * download: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/yi * FAQ: http://haskell.org/haskellwiki/Yi/FAQ * homepage: http://haskell.org/haskellwiki/Yi * check and report issues: http://code.google.com/p/yi-editor/issues/list * darcs repository: http://code.haskell.org/yi * get involved: mailto:[EMAIL PROTECTED] * release notes: http://code.google.com/p/yi-editor/wiki/ReleaseNotes0o4 == Acks == This release is brought to you by: Allan Clark Andrew Birkett Corey O'Connor Duncan Coutts Evan Martin Fraser Wilson Gustav Munkby Gwern Branwen Jean-Philippe Bernardy Krasimr Angelov Nicolas Pouillard Sean Leather Thomas Schilling and all the contributors to the previous versions. ___ 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] Exceptions
aneumann:
Hello,
I think it'd be nice if the compiler could warn me if there are any
exceptions which I'm not catching, similar to checked exceptions in
Java. Does anyone know of a possibility to do that in Haskell?
Adrian
You could provide exception-safe wrappers for the functions you use,
that catch any exception and flatten it to an Either type (or something
similar). Then GHC's usual coverage checking will enforce the handling.
import qualified System.IO
import Control.Exception
maybeReadFile :: FilePath - IO (Maybe String)
maybeReadFile f = handle (\_ - return Nothing)
(Just `fmap` System.IO.readFile f)
{-
*A maybeReadFile /tmp/DOESNOTEXIST
Nothing
-}
main = do
mf - maybeReadFile DOESNOTEXIST
case mf of
Nothing - return ()
Just s - print s
The ability to control exceptions seems like something we should have more
solutions for.
-- Don
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Re: [Haskell-cafe] Cabal files on Windows
On Sun, 27 Jul 2008 03:23:09 +0200, John Lato [EMAIL PROTECTED] wrote: Hello, Can anyone point me to a method for including path names with spaces in a cabal file? I would like to add a line similar to the following: include-dirs: C:\Program Files\program\include and of course a corresponding library as well. [...] Have you tried replacing Program Files with PROGRA~1? This is the old MS-Dos version of the directory name; you can find the old name with command dir /x C:\ , this displays the old version next to the new version of the name. -- 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] Cabal files on Windows
On Sat, 2008-07-26 at 20:23 -0500, John Lato wrote: Hello, Can anyone point me to a method for including path names with spaces in a cabal file? I would like to add a line similar to the following: include-dirs: C:\Program Files\program\include and of course a corresponding library as well. Use Haskell String syntax for paths that contain spaces: include-dirs: C:\\Program Files\\program\\include Duncan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: Yi 0.4.1
Hi Jean-Philippe, Using cabal install: cabal install yi-0.4.1 when I do this on my Windows machine, cabal-install tries to download the unix-2.3.0.0 package, which clearly won't work. How do I get yi to install on Windows? Cheers, /Niklas ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: Yi 0.4.1
jeanphilippe.bernardy: I'm very pleased to announce the 0.4.1 release of the Yi editor. == Yi == Yi is a text editor written and extensible in Haskell. The long-term goal of the Yi project is to provide the editor of choice for Haskell programmers. In the meantime, we have fun by hacking an editor in a decent language :) Yi is not a finished product. This is an alpha-quality release. However, Yi has become a lot more accessible than previously, so if you feel like testing it, now might be a good time to take a look. While the vty frontend is working, the gtk / pango frontends are erroring for me with, $ yi -f pango Launching custom yi: /home/dons/.yi/yi-x86_64-linux yi: exception :: System.Glib.GError.GError Anyone seen this? -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: ANN: Yi 0.4.1
Niklas Broberg niklas.broberg at gmail.com writes: Hi Jean-Philippe, Using cabal install: cabal install yi-0.4.1 when I do this on my Windows machine, cabal-install tries to download the unix-2.3.0.0 package, which clearly won't work. How do I get yi to install on Windows? Vty frontend does not work on win32, so you must install gtk2hs (latest) beforehand. Additionally, I recommend to use cabal install yi-0.4.1 -f-vty -fgtk to force choosing the right options. Cheers, JP. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: ANN: Yi 0.4.1
Don Stewart dons at galois.com writes: $ yi -f pango Launching custom yi: /home/dons/.yi/yi-x86_64-linux yi: exception :: System.Glib.GError.GError Anyone seen this? Consistently on x64. The pango stuff is generally unstable anyway. I'm not sure what's to blame. -- JP ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re[2]: [Haskell-cafe] Cabal files on Windows
Hello Henk-Jan, Sunday, July 27, 2008, 11:36:32 PM, you wrote: Can anyone point me to a method for including path names with spaces in a cabal file? I would like to add a line similar to the following: Have you tried replacing Program Files with PROGRA~1? This is the old i don't followed discussion but if this meant for distributable packages, the following problems exist: 1. it may be progra~2 or ~3 2. it's possible to entirely disable short names generation on ntfs -- Best regards, Bulatmailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: ANN: Yi 0.4.1
Thanks, after installing gtk2hs and using the flags you told me I managed to install it just fine. However... $ yi -f pango Launching custom yi: /home/dons/.yi/yi-x86_64-linux yi: exception :: System.Glib.GError.GError Anyone seen this? Consistently on x64. The pango stuff is generally unstable anyway. I'm not sure what's to blame. ... I got this error too, and I'm on Win32. :-( Cheers, /Niklas ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: ANN: Yi 0.4.1
Niklas Broberg niklas.broberg at gmail.com writes: Thanks, after installing gtk2hs and using the flags you told me I managed to install it just fine. However... Good :) The pango stuff is generally unstable anyway. I'm not sure what's to blame. ... I got this error too, and I'm on Win32. The gtk frontend should not suffer from this: yi -fgtk -- JP. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: ANN: Yi 0.4.1
The gtk frontend should not suffer from this: yi -fgtk C:\Documents and Settings\Niklas Brobergyi -fgtk yi: exception :: System.Glib.GError.GError :-( Cheers, /Niklas ps. If I installed it with -f-vty -fgtk, shouldn't gtk be the default when running? :-) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: Yi 0.4.1
On Sun, Jul 27, 2008 at 03:08:04PM +, Jean-Philippe Bernardy wrote: I'm very pleased to announce the 0.4.1 release of the Yi editor. great, i can't wait to check it out ... i get the following error when installing via hackage/cabal (ghc 6.8.1, cabal 1.4.0.1): Yi/Buffer.hs:253:0: No instance for (Typeable4 RWS) arising from the 'deriving' clause of a data type declaration at Yi/Buffer.hs:(253,0)-(254,101) Possible fix: add an instance declaration for (Typeable4 RWS) When deriving the instance for (Typeable1 BufferM) Yi/Buffer.hs:256:0: Can't make a derived instance of `Typeable4 RWS' (even with cunning newtype deriving: the representation type has wrong kind) In the stand-alone deriving instance for `Typeable4 RWS' any ideas what's going wrong? is it finally time to upgrade my ghc installation? sk ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: ANN: Hayoo! beta 0.2
Timo B. Hübel wrote: we are pleased to announce the second beta release of Hayoo!, a Haskell API search engine providing advanced features like suggestions, find-as-you-type, fuzzy queries and much more. Visit Hayoo! here: http://holumbus.fh-wedel.de/hayoo The major change is the inclusion of all packages available on Hackage, i.e. the documentation of the latest versions of all packages is included in the index. Unfortunately we had to drop the direct links to the source code, as the documentation on Hackage is currently generated without source code. But as soon as this changes, we will include these links again. Additionally, we added some tweaks to the interface which make the browser history/the back button work (at least in Firefox). Please bear in mind that this is still a beta release and we are continuously working on further improvements. Any suggestions and feedback is highly welcomed. Well, it is currently not in a usable state: the page randomly inserts funny characters into the text input field. (I'm using Konqueror) Cheers Ben ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: Re[2]: [Haskell-cafe] Cabal files on Windows
On Mon, 2008-07-28 at 00:27 +0400, Bulat Ziganshin wrote: Hello Henk-Jan, Sunday, July 27, 2008, 11:36:32 PM, you wrote: Can anyone point me to a method for including path names with spaces in a cabal file? I would like to add a line similar to the following: Have you tried replacing Program Files with PROGRA~1? This is the old i don't followed discussion but if this meant for distributable packages, the following problems exist: 1. it may be progra~2 or ~3 2. it's possible to entirely disable short names generation on ntfs None of this is necessary. Paths with spaces are just fine if you use the Haskell String syntax. Duncan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Cabal files on Windows
On Sun, Jul 27, 2008 at 3:25 PM, Duncan Coutts [EMAIL PROTECTED] wrote: On Sat, 2008-07-26 at 20:23 -0500, John Lato wrote: Hello, Can anyone point me to a method for including path names with spaces in a cabal file? I would like to add a line similar to the following: include-dirs: C:\Program Files\program\include and of course a corresponding library as well. Use Haskell String syntax for paths that contain spaces: include-dirs: C:\\Program Files\\program\\include Hi Duncan, Thanks, this worked (mostly). Although I had to change the line to include-dirs: \C:\\Program Files\\program\\include\ so that the path would be passed properly to cpp through c2hs. Is this documented anywhere? I've been poring over the cabal guide trying to find this, with no success. Thank you, John ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Control.Concurrent.forkIO versus Control.Parallel.par
Hello. I have a question about parallel computation in Haskell. After browsing the GHC library documentation, I was left with impression that there are two separate mechanisms for expressing concurrency: Control.Parallel.par for pure computations and Control.Concurrent.forkIO for computations in IO monad. This dichotomy becomes a problem when one tries to use concurrency from a monad transformer, though I'm sure that's not the only such situation. One cannot assume that the base monad is IO so forkIO cannot be used, while Control.Parallel.par won't run monads. My first solution was to replace the base monad class for the monad transformer by the following ParallelizableMonad class: class Monad m = ParallelizableMonad m where parallelize :: m a - m b - m (a, b) parallelize ma mb = do a - ma b - mb return (a, b) instance ParallelizableMonad Identity where parallelize (Identity a) (Identity b) = Identity (a `par` (b `pseq` (a, b))) instance ParallelizableMonad IO where parallelize ma mb = do va - newEmptyMVar vb - newEmptyMVar forkIO (ma = putMVar va) forkIO (mb = putMVar vb) a - takeMVar va b - takeMVar vb return (a, b) I tested this solution, and it worked for IO computations in the sense that they used both CPUs. The test also ran slower on two CPUs that on one, but that's beside the point. Then I realized that par can, in fact, be used on any monad, it just needs a little nudge: parallelize :: m a - m b - m (a, b) parallelize ma mb = let a = ma = return b = mb = return in a `par` (b `pseq` liftM2 (,) a b) However, in this version the IO monadic computations still appear to use only one CPU. I cannot get par to parallelize monadic computations. I've used the same command-line options in both examples: -O -threaded and +RTS -N2. What am I missing? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] multicore programming ...
Hello, I have written quite a bit of multi-threaded code in ANSI C and C++ using mainly Posix threads and some using Win32 API threads. IMO now seems to be a huge opportunity for FPLs to shine .. In any case, now there seems to be an emerging crisis in the computer industry in multithread scalability over large multicore: http://www.hackinthebox.org/modules.php?op=modloadname=Newsfile=articlesid=27292mode=threadorder=0thold=0. This is kind of a wrag quote. Do others have more substantial URLs on programming large multi-cores? Kind regards, Vasili ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Control.Concurrent.forkIO versus Control.Parallel.par
I think a better way to look at it is that Haskell has two separate mechanisms for different *notions* of concurrency -- forkIO for actual concurrent computation which needs explicit threads and communication (and within that, either semaphore-based communication with MVars or transactional control with TVars and STM), and par for parallelism which is to express computations that are innately parallel. See, e.g. the GHC users manual which defines them as such: * Parallelism means running a Haskell program on multiple processors, with the goal of improving performance. Ideally, this should be done invisibly, and with no semantic changes. * Concurrency means implementing a program by using multiple I/O- performing threads. While a concurrent Haskell program can run on a parallel machine, the primary goal of using concurrency is not to gain performance, but rather because that is the simplest and most direct way to write the program. Since the threads perform I/O, the semantics of the program is necessarily non-deterministic. (http://www.haskell.org/ghc/docs/latest/html/users_guide/lang- parallel.html) In any case, I suspect that your second parallelize function doesn't work right because \x - x = return is an effective no-op, modulo strictness characteristics of =. And in any case, it can't be evaluated until it is called in a particular monadic environment which is provided, sequencing and all, via liftM2. One can't parallelize in an arbitrary monad in any case, at least without making a number of decisions. E.g., what's the resultant state after two parallel computations are run in a state monad? So if you're using concurrency with a monad transformer, you probably might want to start by stripping back the layers of the concurrent part of your algorithm to the minimum possible, and then explicitly managing passing state into the various forked computations, which can then be wrapped in as many runReaderT or such calls as necessary. On another, general, note, unless you're very careful, mixing IO into your algorithm will probably result in very underperformant parallel code, since it will be IO rather than processor bound. Again the point from the GHC manual that the primary goal of using concurrency is not to gain performance, but rather because that is the simplest and most direct way to write the program seems appropriate. Additionally, many have found it easier at this stage to get good performance out of writing parallel code with concurrent mechanisms rather than `par`, because careless use of `par` will tend to add as much overhead in spark creation as is saved with multiprocessing, while an explicit work queue can be easier to reason about. Regards, S. On Jul 27, 2008, at 10:49 PM, Mario Blažević wrote: Hello. I have a question about parallel computation in Haskell. After browsing the GHC library documentation, I was left with impression that there are two separate mechanisms for expressing concurrency: Control.Parallel.par for pure computations and Control.Concurrent.forkIO for computations in IO monad. This dichotomy becomes a problem when one tries to use concurrency from a monad transformer, though I'm sure that's not the only such situation. One cannot assume that the base monad is IO so forkIO cannot be used, while Control.Parallel.par won't run monads. My first solution was to replace the base monad class for the monad transformer by the following ParallelizableMonad class: -- -- class Monad m = ParallelizableMonad m where parallelize :: m a - m b - m (a, b) parallelize ma mb = do a - ma b - mb return (a, b) instance ParallelizableMonad Identity where parallelize (Identity a) (Identity b) = Identity (a `par` (b `pseq` (a, b))) instance ParallelizableMonad IO where parallelize ma mb = do va - newEmptyMVar vb - newEmptyMVar forkIO (ma = putMVar va) forkIO (mb = putMVar vb) a - takeMVar va b - takeMVar vb return (a, b) -- -- I tested this solution, and it worked for IO computations in the sense that they used both CPUs. The test also ran slower on two CPUs that on one, but that's beside the point. Then I realized that par can, in fact, be used on any monad, it just needs a little nudge: -- -- parallelize :: m a - m b - m (a, b) parallelize ma mb = let a = ma = return b = mb = return in a `par` (b `pseq` liftM2 (,) a b) --
Re: [Haskell-cafe] Control.Concurrent.forkIO versus Control.Parallel.par
On Mon, Jul 28, 2008 at 2:49 AM, Mario Blažević [EMAIL PROTECTED] wrote: parallelize :: m a - m b - m (a, b) parallelize ma mb = let a = ma = return b = mb = return in a `par` (b `pseq` liftM2 (,) a b) See Sterling's reply for an actual answer to your question, but note that one of the monad laws is: m = return = m (i.e. return is a right identity of bind) That means your code can be reduced to: parallelize ma mb = ma `par` (mb `pseq` liftM2 (,) ma mb) Which, as Sterling points out, is *not* doing what you think it is. Luke ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] carry state around ....
Hi Duncan and Brandon,
I am moving to the ForeignPtr strategy. However, I always try to learn
from where I am before going to a new approach. I have discovered by
debugging that the AIOCB peek is working; however, passing the peeked
AIOCB back to the caller(i.e. the test program) is not working .. please let
me try to demonstrate below. I have been staring at my Haskell code many,
many times sigh ...
0)
IN PEEK CODE .. aioErrorCode = 115
IN PEEK CODE .. aioReturnValue = 0
aioWrite after aio_write
IN PEEK CODE .. aioErrorCode = 115
IN PEEK CODE .. aioReturnValue = 0
*aiocb dump***
fd = 3
opcode = 1
prio = 0
offset = 0
nbytes = 20
next = 0x
absprio = 0
policy = 0
errocode = 115 correct ... INPROGRESS errno
return value = 0
return from call of Haskell function aioWrite here
... below errocode has changed from 115 to 0 ... somehow my return AIOCB
is corrupting the state/value of AIOCB
*aioWrite dumpAIOCB
*aiocb dump***
fd = 3
opcode = 0
prio = 0
offset = 0
nbytes = 20
next = 0x
absprio = 0
policy = 0
errocode = 0 incorrect Errno ... should
still be IN PROGRESS.
return value = 0
1) aioWrite ... the function marshalling(poke) and unmarshalling(peek) an
AIOCB:
aioWrite :: AIOCB - IO AIOCB
aioWrite aiocb = do
allocaBytes (#const sizeof(struct aiocb)) $ \ p_aiocb - do
poke p_aiocb aiocb
putStrLn aioWrite before aio_write
aiocb1 - peek p_aiocb
dumpAIOCB aiocb1
throwErrnoIfMinus1 aioWrite (c_aio_write p_aiocb)
aiocb - peek p_aiocb
putStrLn aioWrite after aio_write
aiocb - peek p_aiocb
dumpAIOCB aiocb
-- putStrLn aioWrite after aio_write
-- aiocb1 - peek p_aiocb
-- dumpAIOCB aiocb1
return (aiocb)
foreign import ccall safe aio.h aio_write
c_aio_write :: Ptr AIOCB - IO CInt
2) an AIOCB:
data LioOps = LioRead | LioWrite | LioNop
data AIOCB = AIOCB {
aioFd :: Fd,
aioLioOpcode :: Int,
aioReqPrio :: Int,
aioOffset :: FileOffset,
aioBuf :: Ptr Word8,
aioBytes :: ByteCount,
aioSigevent :: Sigevent,
-- Internal members
aioNext :: Ptr AIOCB,
aioAbsPrio :: Int,
aioPolicy :: Int,
aioErrorCode :: Int,
aioReturnValue :: ByteCount
}
3) poke/peek
instance Storable AIOCB where
sizeOf _ = (#const sizeof (struct aiocb))
alignment _ = 1
poke p_AIOCB (AIOCB aioFd aioLioOpcode aioReqPrio aioOffset aioBuf
aioBytes aioSigevent aioNext aioAbsPrio aioPolicy aioErrorCode
aioReturnValue) = do
(#poke struct aiocb, aio_fildes) p_AIOCB aioFd
(#poke struct aiocb, aio_lio_opcode) p_AIOCB aioLioOpcode
(#poke struct aiocb, aio_reqprio) p_AIOCB aioReqPrio
(#poke struct aiocb, aio_offset) p_AIOCB aioOffset
(#poke struct aiocb, aio_buf) p_AIOCB aioBuf
(#poke struct aiocb, aio_nbytes) p_AIOCB aioBytes
(#poke struct aiocb, aio_sigevent) p_AIOCB aioSigevent
(#poke struct aiocb, __next_prio) p_AIOCB aioNext
(#poke struct aiocb, __abs_prio) p_AIOCB aioAbsPrio
(#poke struct aiocb, __policy) p_AIOCB aioPolicy
(#poke struct aiocb, __error_code) p_AIOCB aioErrorCode
(#poke struct aiocb, __return_value) p_AIOCB aioReturnValue
peek p_AIOCB = do
aioFd - (#peek struct aiocb, aio_fildes) p_AIOCB
aioLioOpcode - (#peek struct aiocb, aio_lio_opcode) p_AIOCB
aioReqPrio - (#peek struct aiocb, aio_reqprio) p_AIOCB
aioOffset - (#peek struct aiocb, aio_offset) p_AIOCB
aioBuf - (#peek struct aiocb, aio_buf) p_AIOCB
aioBytes - (#peek struct aiocb, aio_nbytes) p_AIOCB
aioSigevent - (#peek struct aiocb, aio_sigevent) p_AIOCB
aioNext - (#peek struct aiocb, __next_prio) p_AIOCB
aioAbsPrio - (#peek struct aiocb, __abs_prio) p_AIOCB
aioPolicy - (#peek struct aiocb, __policy) p_AIOCB
aioErrorCode - (#peek struct aiocb, __error_code) p_AIOCB
putStrLn (IN PEEK CODE .. aioErrorCode = ++ (show aioErrorCode))
aioReturnValue - (#peek struct aiocb, __return_value) p_AIOCB
putStrLn (IN PEEK CODE .. aioReturnValue = ++ (show
aioReturnValue))
return (AIOCB aioFd aioLioOpcode aioReqPrio aioOffset aioBuf aioBytes
aioSigevent aioNext aioAbsPrio aioPolicy aioErrorCode aioReturnValue)
Kind regards, Vasili
On Sun, Jul 20, 2008 at 6:51 AM, Duncan Coutts
[EMAIL PROTECTED]wrote:
On Sat, 2008-07-19 at 23:55 -0500, Galchin, Vasili wrote:
yes Duncan I am trying to pass-by-value. I am familiar with
ForeignPtr; however, I don't comprehend what you and Brandon are
suggesting to do. Could either of you provide a code illustration or
point at existing code to illustrate your approach?
Take a look at John Meacham's RSA example.
So at the moment you're using using Storable and a Haskell record, say:
data
