- Haskell-Cafe - Haskell.org

Data.Unique not "safe" in concurrent environments (or brain burned)?
by Neil Davies 01 Sep '07

01 Sep '07

Hi, I was looking over the libraries for bits of GHC (no doubt a standard form of relaxation for readers of this list), and noticed the following statement (in Data.Unique): -- | Creates a new object of type 'Unique'. The value returned will -- not compare equal to any other value of type 'Unique' returned by -- previous calls to 'newUnique'. This set me thinking - so I looked at the code newUnique :: IO Unique newUnique = do val <- takeMVar uniqSource let next = val+1 putMVar uniqSource next return (Unique next) In the concurrent execution world in which we live - I don't think that the implementation supports the "uniqueness" statement above - or am I not understanding something? Cheers Neil

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GHC 6.6.1 binary package for Ubuntu available?
by Sukit Tretriluxana 01 Sep '07

01 Sep '07

Hi, I am wondering if there is the binary package for GHC 6.6.1 for Ubuntu. I searched in the package manager and I only see the version 6.6. Thanks, Ed

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Re: trouble compiling regex posix head (I think >0.92) on ghc 6.7
by Thomas Hartman 01 Sep '07

01 Sep '07

I darcs pulled cabal head to get latest cabal, removed -Werror from GHC-Options in the cabal file, removed HsRegexPosixConfig.h and tried again with the same result. It seems to really want that file. With, it installs, without, no install. $ darcs whatsnew { hunk ./regex-posix.cabal 16 -Build-Depends: regex-base >= 0.80, base >= 2.0 +Build-Depends: regex-base >= 0.80, base >= 2.0, array, containers, byt estring hunk ./regex-posix.cabal 32 -GHC-Options: -Wall -Werror -O2 +GHC-Options: -Wall -O2 hunk ./regex-posix.cabal 43 -Include-Dirs: include +Include-Dirs: include/regex } Chris Kuklewicz <haskell(a)list.mightyreason.com> 08/30/2007 12:34 PM To Thomas Hartman/ext/dbcom@DBAmericas cc haskell-cafe(a)haskell.org, "cvs-ghc(a)haskell.org" <cvs-ghc(a)haskell.org> Subject Re: trouble compiling regex posix head (I think >0.92) on ghc 6.7 Thomas Hartman wrote: > > I'm trying to compile regex-posix on ghc 6.7. (Ultimate goal: happs on > 6.7). I have not explored ghc 6.7. You should also try posting on the <glasgow-haskell-users(a)haskell.org> mailing list. > > First, I patched by changing the cabal file to be compatible with the > new libraries broken out of base. I also had to add HsRegexPosixConfig.h > to include/regex (I just copied it from somewhere else on my hard drive > where I guess it had been put by an earlier regex-posix install, I don't > know if it's compatible here but at least it permitted things to compile > further.) I had no idea what HsRegexPosixConfig was, and I have no such file at all. So I looked in Wrap.hsc and found: > #ifdef HAVE_REGEX_H > #define HAVE_REGCOMP 1 > #else > #ifndef __NHC__ > #include "HsRegexPosixConfig.h" > #else > #define HAVE_REGEX_H 1 > #define HAVE_REGCOMP 1 > #endif > #endif Note that I did not write that section -- that was added by someone else. So HsRegexPosixConfig.h should only matter if HAVE_REGEX_H is undefined. The regex-base.cabal file says: "CC-Options: -DHAVE_REGEX_H" So unless Cabal is having a very very bad day, I assume that HsRegexPosixConfig.h is never needed. That it matters to your build to have that file seems _wrong_ to me. The only header file it should need is "regex.h" > Setup.hs build -v3 had a lot of warnings but didn't seem to fail. > However, Setup.hs install -v3 didn't work. You might try to change the cabal file. Currently I think it is "GHC-Options: -Wall -Werror -O2" and remove -Werror "GHC-Options: -Wall -O2" And you can change the cabal "Include-Dirs" to point to wherever it will find "regex.h" > the problem in build seems to occur around "upsweep partially failed or > main not exported"... That means nothing to me. > > [6 of 6] Compiling Text.Regex.Posix ( Text/Regex/Posix.hs, > dist/build/Text/Regex/Posix.o ) > *** Parser: > *** Renamer/typechecker: > > Text/Regex/Posix.hs:57:2: > Warning: The export item `module Text.Regex.Posix.String' exports > nothing > > Text/Regex/Posix.hs:59:2: > Warning: The export item `module Text.Regex.Posix.Sequence' exports > nothing > > Text/Regex/Posix.hs:61:2: > Warning: The export item `module Text.Regex.Posix.ByteString' > exports nothing > > Text/Regex/Posix.hs:63:2: > Warning: The export item `module Text.Regex.Posix.ByteString.Lazy' > exports nothing Those warning are slightly bogus. Including the module should export the instances. > *** Deleting temp files: > Deleting: /tmp/ghc9618_0/ghc9618_0.s > Warning: deleting non-existent /tmp/ghc9618_0/ghc9618_0.s > Upsweep partially successful. > *** Deleting temp files: > Deleting: > link(batch): upsweep (partially) failed OR > Main.main not exported; not linking. > *** Deleting temp files: > Deleting: > *** Deleting temp dirs: > Deleting: /tmp/ghc9618_0 > > complete output (along with patch) is attached. > > I'd appreciate any advice. > > best, thomas. > > --- This e-mail may contain confidential and/or privileged information. If you are not the intended recipient (or have received this e-mail in error) please notify the sender immediately and destroy this e-mail. Any unauthorized copying, disclosure or distribution of the material in this e-mail is strictly forbidden.

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trying to install gutsy's libghc6-mtl-dev from source on feisty
by Anatoly Yakovenko 01 Sep '07

01 Sep '07

i have ghc6_6.6.1-2ubuntu2_i386.deb and ghc6-prof_6.6.1-2ubuntu2_i386.deb installed, but i cant seem to get mtl to install, can someone tell me what this output means? i just switched to a debian based system from gentoo, so i dont grok dpkg yet: aeyakovenko@snowcrash:~$ sudo dpkg -i libghc6-mtl-dev_1.0.1-2_i386.deb (Reading database ... 129709 files and directories currently installed.) Preparing to replace libghc6-mtl-dev 1.0-3 (using libghc6-mtl-dev_1.0.1-2_i386.deb) ... ghc-pkg: cannot find package mtl-1.0 dpkg: warning - old pre-removal script returned error exit status 1 dpkg - trying script from the new package instead ... ghc-pkg: cannot find package mtl-1.0 dpkg: error processing libghc6-mtl-dev_1.0.1-2_i386.deb (--install): subprocess new pre-removal script returned error exit status 1 Reading package info from stdin ... done. ghc-pkg: dependency base-2.0 doesn't exist (use --force to override) dpkg: error while cleaning up: subprocess post-installation script returned error exit status 1 Errors were encountered while processing: libghc6-mtl-dev_1.0.1-2_i386.deb

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Haskell on the Playstation 3? :-)
by Peter Verswyvelen 31 Aug '07

31 Aug '07

Game developers are really struggling to get performance out of the Playstation 3 console. This console has a single PowerPC CPU with 6 Cell SPU coprocessors, all running at 3.3GHz. These SPUs have 256KB very high speed local RAM, and data from the 512MB main memory can stream in and out via DMA into these SPUs. The problem is that with imperative approaches this is a nightmare to manage.. It would be a very cool project to show that Haskell could run on such a platform, making it easier to take advance of its awesome power J Oh well, I'm just brainstorming here. Cheers, Peter BTW: This Cell platform also seemed to be offered for scientific computing in standard workstation PCs, so it would not just be for the Playstation 3.

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Newbie question: Why gfoldl has this strange type?
by Rodrigo Geraldo 31 Aug '07

31 Aug '07

Hi! I am a novice in Haskell, and particularly I have interested in generic programming. This interest motivated me to read paper Scrap your boilerplate: A practical design pattern for generic programming, but I didn't understand the type of the function gfoldl, that was present in class Term (Data). Somebody could help me to understand the type of this function? Thanks... Rodrigo

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darcs behind firewall
by Sukit Tretriluxana 31 Aug '07

31 Aug '07

Hi all, Does anyone know how to specify proxy server and port for darcs to use when it connects to servers? I am behind firewall most of the time and all requests have to go through a proxy. Thanks, Ed

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Re: [Haskell-cafe] let and fixed point operator
by Dan Piponi 31 Aug '07

31 Aug '07

On 8/30/07, jerzy.karczmarczuk(a)info.unicaen.fr <jerzy.karczmarczuk(a)info.unicaen.fr> wrote: > Dan Piponi writes: > > In Haskell, there is no box. > > Well, there are boxes... > But there also thunks and latent, yet-unevaluated graphs... But the point of Haskell is to provide an abstraction that hides these details from you. (Though ultimately it's a leaky abstraction and there comes a point where you do need to know about these things.) > Anyway, I believe strongly that ALL people who have problems with the > Haskell protocole, and they are numerous, I teach a good sample of them, > should be encouraged to learn Prolog. I'd second that. It's hard to see the difference between declarative and imperative programming when you only have one instance of a declarative language from which to generalise. -- Dan

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happs on ghc 6.7 won't work because of dependency on Data.Binary (everything that depends on Data.Binary broken at present) ( unknown symbol `stg_uncheckedShiftRL64' )
by Thomas Hartman 31 Aug '07

31 Aug '07

happs on ghc 6.7 won't work because of dependency on Data.Binary, since everything that depends on Data.Binary is broken at present. This is for Data.Binary installed via cabal from darcs get --partial http://darcs.haskell.org/binary . Cabal installed without any errors, but perhaps there should have been one since it appears broke. So I think my project of using the ghc debugger to help understand happs is on ice until this gets resolved. Unless this has been fixed since August 16. (Anyone out there got a more recent version?) $ cat UseDataBinary.hs import Data.Binary main = putStrLn "hello world" $ /usr/local/bin/ghc-6.6.1 -e 'main' UseDataBinary.hs hello world $ /usr/local/bin/ghc-6.7.20070816 -e 'main' UseDataBinary.hs <interactive>: /usr/local/lib/binary-0.3/ghc-6.7.20070816/HSbinary-0.3.o: unknown symbol `stg_uncheckedShiftRL64' ghc-6.7.20070816: unable to load package `binary-0.3' $ /usr/local/bin/ghc-6.7.20070816 -e '' UseDataBinary.hs --- This e-mail may contain confidential and/or privileged information. If you are not the intended recipient (or have received this e-mail in error) please notify the sender immediately and destroy this e-mail. Any unauthorized copying, disclosure or distribution of the material in this e-mail is strictly forbidden.

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redirecting stdout
by Chad Scherrer 31 Aug '07

31 Aug '07

Is it possible to write a function redirect :: Handle -> IO () -> IO () so that "redirect h action" is just like action, except that all the output written to stdout now gets sent to h instead? Thanks, Chad

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