- Haskell-Cafe - Haskell.org

How to use lib compat-base3 in ghc 6.10?
by Magicloud 29 Oct '08

29 Oct '08

Hi, Xmonad needs Data.Generics from base3. And I found out that there is a "compat-base3" in ghc 6.10, which has Data.Generics. But `ghc -v` reports that base-3.0.3.0 is hidden. So I wonder how could I compile Xmonad with ghc 6.10? Thanks.

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Re: [darcs-users] Poll: Do you need to be able to build darcs from source on GHC 6.6?
by Matthias Kilian 29 Oct '08

29 Oct '08

On Wed, Oct 29, 2008 at 12:11:22PM +1100, Trent W. Buck wrote: > To my mind, the benefit is negligible, because: > > Then we still have OpenBSD users. > > means we can't drop GHC 6.6 support. Also, note that Lenny has 6.8, > and it is scheduled to become stable Real Soon Now. Ok, it all depends on when the next release of darcs will be ready and when I (or someone else) gets ghc-6.8 or 6.10 done for OpenBSD (yes, I'm working on this, even after I dropped maintainership from our ghc port). I *hope* to get a working ghc-6.10 port for OpenBSD to the end of this year, and I guess that's a short enough timeline that darcs could drop 6.6 support if it's really necessary. Ciao, Kili

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Fwd: [Haskell-cafe] ANNOUNCE: Data.TCache 0.5.1
by Alberto G. Corona 29 Oct '08

29 Oct '08

---------- Forwarded message ---------- From: Alberto G. Corona <agocorona(a)gmail.com> Date: 2008/10/29 Subject: Re: [Haskell-cafe] ANNOUNCE: Data.TCache 0.5.1 To: Joachim Breitner <mail(a)joachim-breitner.de> I developed it in 2006. At this time I think that Happs did not used STM. I do not know Happs.State very well. The main difference is that it is far far simple (only a handfull of methods exported) it is configurable and permit the full semantic of TVars without loosing content persistence. Also, the query is based on let´s say patterns. A pattern is a partilally filled object. enough to deduce the key. the interface is very natural. For example: withResources [ User{ name= "Alberto"} , Product{ id="Playstation"} buyIt where buyIt [Just user, Just product]= [user{due= due user +price product}, product{ stock= stock product -1]] buyIt _ = error "either the user or the product not found" Just prod <- getResource Product{ id="Playstation"} bla bla bla 2008/10/29 Joachim Breitner <mail(a)joachim-breitner.de> > Hi, > > Am Dienstag, den 28.10.2008, 23:26 +0100 schrieb Alberto G. Corona : > > Data.Tcache is a transactional cache with configurable persistence. It > > tries to simulate Hibernate for Java or Rails for Ruby. The main > > difference is that transactions are done in memory trough STM. There > > are transactional cache implementations for some J2EE servers like > > JBOSS. > > > > TCache uses STM . It can atomically apply a function to a list of > > cached objects. The resulting objects go back to the cache > > (withResources). It also can retrieve these objects (getResources). > > Persistence can be syncronous (syncCache) or asyncronous, wtih > > configurable time between cache writes and configurable cache > > clearance strategy. the size of the cache can be configured too . All > > of this can be done trough clearSyncCacheProc. Even the TVar variables > > can be accessed directly (getTVar) to acceess all the semantic of > > atomic blocks while maintaining the persistence of the TVar updates. > > > > Persistence can be defined for each object.: Each object must have a > > defined key, a default filename path (if applicable). Persistence is > > pre-defined in files, but the readResource writeResource and > > delResource methods can be redefined to persist in databases or > > whatever. > > Interesting. Without much deep knowledge, this sounds similar to > HAppS.State. Where are the differences? > > Greetings, > Joachim > > -- > Joachim "nomeata" Breitner > mail: mail(a)joachim-breitner.de | ICQ# 74513189 | GPG-Key: 4743206C > JID: nomeata(a)joachim-breitner.de | http://www.joachim-breitner.de/ > Debian Developer: nomeata(a)debian.org > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > >

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Re: Poll: Do you need to be able to build darcs from source on GHC 6.6?
by trentbuck＠gmail.com 29 Oct '08

29 Oct '08

"Trent W. Buck" <trentbuck(a)gmail.com> writes: > On Wed, Oct 29, 2008 at 12:39:28PM +0900, Stephen J. Turnbull wrote: >> Trent W. Buck writes: >> >> > In an ideal world, we just make sure it builds with the latest tools, >> > and let the users of stable distros worry about telling us if it >> > breaks against whatever versions they care about. >> >> This is very disappointing coming from (some) developers of *version >> control software*! You'd think they, of all software developers, >> would be sympathetic to the need to, well, control versions! > > Let me clarify that the above are my *personal* opinions, and I'm not > really involved in the Darcs Haskell code -- just the surrounding > build and documentation infrastructure. > > I'm speaking more from my role as a Debian maintainer and user than as > a member of the Darcs comunity. Actually, even more than that I'm speaking as someone who for years tried to keep shell scripts portable and POSIX clean and working even on ten-year-old versions of Solaris... before deciding that I was investing waaaaay too much time testing on those systems considering approximately zero of my users ran them. So I said "fuck it, I'll use bash and assume GNU coreutils, and if it breaks on someone's system, they'll tell me."

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Re: [darcs-users] Poll: Do you need to be able to build darcs from source on GHC 6.6?
by David Roundy 29 Oct '08

29 Oct '08

On Wed, Oct 29, 2008 at 12:11:22PM +1100, Trent W. Buck wrote: > > Thus I think the version/upgrade matrix is handy so we can > > plan/schedule when it is safe to drop support. > > In an ideal world, we just make sure it builds with the latest tools, > and let the users of stable distros worry about telling us if it > breaks against whatever versions they care about. No, in the idea world we'd try to be supportive of our contributors and maintainers by not requiring that they install the latest tools. -- David Roundy http://www.darcs.net

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computational overhead of the "data" declarations
by Daryoush Mehrtash 29 Oct '08

29 Oct '08

I Haskell School of Expression (p172), it says: A newtype declaration is just like a data declaration, except that it can > only be used to defined data types with single constructor. The new data > type is different from the analogous one created by a data declaration, in > that there is no computational overhead in having the constructor.... You > can think of a newtype as defining a "new type" with exactly the same > structure, behaviour, and performance as the underlying type. > What is (or where do you see) the computational overhead of the "data" declrations?

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ANNOUNCE: Data.TCache 0.5.1
by Alberto G. Corona 28 Oct '08

28 Oct '08

I uploaded TCache to hackage.org. Data.Tcache is a transactional cache with configurable persistence. It tries to simulate Hibernate for Java or Rails for Ruby. The main difference is that transactions are done in memory trough STM. There are transactional cache implementations for some J2EE servers like JBOSS. TCache uses STM . It can atomically apply a function to a list of cached objects. The resulting objects go back to the cache (withResources). It also can retrieve these objects (getResources). Persistence can be syncronous (syncCache) or asyncronous, wtih configurable time between cache writes and configurable cache clearance strategy. the size of the cache can be configured too . All of this can be done trough clearSyncCacheProc. Even the TVar variables can be accessed directly (getTVar) to acceess all the semantic of atomic blocks while maintaining the persistence of the TVar updates. Persistence can be defined for each object.: Each object must have a defined key, a default filename path (if applicable). Persistence is pre-defined in files, but the readResource writeResource and delResource methods can be redefined to persist in databases or whatever. There is a sample.hs that explain the main features.

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Functional MetaPost in 5 Steps
by Jared Updike 28 Oct '08

28 Oct '08

I'm interested in using Functional MetaPost on Mac OS X (or FreeBSD). I'm looking for a tutorial like: http://haskell.org/haskellwiki/Haskell_in_5_steps but for FMP. I can't even get a simple example to show up in a PDF file: ------------------- import FMP ... (see full code below) myPicture = text "Hello World" main = do print $ emit $ metaPost 1 myPicture params ---------- When run, this emits MetaPost, which, after running through my shell script, below, won't show up in my PDF... (this same TeX file will show an .eps figure I made with PyX, the Python equivalent of FMP, when I change includegraphics to use that file instead of test.1) What am I missing? If I can get this working I will gladly write the FMP 5 Step Tutorial. I like the idea of using FMP but I can't for the life of me understand why running a toy example is so non-trivial. (Not to mention undocumented... the manual and tutorials are very compelling but they don't mention how to get a viewable PDF out of any of the otherwise enticing examples.) Jared. Relevant almost working code: Test.hs: ------------------- import FMP params = Parameters { prolog = "verbatimtex\n\ \\\documentclass{article}\n\ \\\begin{document}\n\ \etex\n\n\ \input boxes\n\ \input FuncMP\n\n", epilog= "\n\n\\end", defaultDX= 3, defaultDY= 3, textDX= 2, textDY= 2, newmp= True, funcmpRTS= "IGNORE", --"+RTS -H40m -K3M -RTS", funcmpBin= "IGNORE", -- "~/FuncMP-1.2/FuncMP", mpBin= "IGNORE" -- "MPINPUTS=:~/FuncMP-1.2 TEX=latex mpost " } myPicture = text "blah" main = do print $ emit $ metaPost 1 myPicture params ---------- test.tex: ----------- \documentclass[12pt]{article} \usepackage[dvipdfm]{graphicx} \begin{document} \section*{Heading} \begin{figure} \begin{center} \includegraphics{test.1} \end{center} \end{figure} \end{document} --------------- shell script: ------ #!/bin/sh ghc --make Test.hs && \ ./Test > test.mp && \ mpost test.mp && \ latex test.tex && \ latex test.tex && \ dvipdfm test.dvi && \ open test.pdf # MacOS X runs my pdf in preview -----------

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strange ghc output
by brad clawsie 28 Oct '08

28 Oct '08

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 i have a small program i have been using routinely that has stopped working. the last alteration of my install configuration was to upgrade the haskell-feed package as arch linux recommended. here is the error i get: - ----- $ runghc newspage.hs GHCi runtime linker: fatal error: I found a duplicate definition for symbol fps_minimum whilst processing object file /usr/lib/bytestring-0.9.1.3/ghc-6.8.2/HSbytestring-0.9.1.3.o This could be caused by: * Loading two different object files which export the same symbol * Specifying the same object file twice on the GHCi command line * An incorrect `package.conf' entry, causing some object to be loaded twice. GHCi cannot safely continue in this situation. Exiting now. Sorry. - ----- i have reinstalled the haskell-bytestring package, to no avail. here is the actual code i am trying to run: http://hpaste.org/11514#a0 its fairly straightforward. any clues? thanks - brad -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) iEYEARECAAYFAkkF8ScACgkQxRg3RkRK91OosgCfeZIA378PleCnaxwymabNz97F TXAAnRzOhL4zQ9n9RG1oDp146a1b4ajK =qtCU -----END PGP SIGNATURE-----

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using ghc as a library
by Anatoly Yakovenko 28 Oct '08

28 Oct '08

so I am trying to figure out how to use ghc as a library. following this example, http://www.haskell.org/haskellwiki/GHC/As_a_library, i can load a module and examine its symbols: module Main where import GHC import GHC.Paths ( libdir ) import DynFlags ( defaultDynFlags ) import System.Environment import Data.Maybe import Outputable main = do args <- getArgs let file = head $ args rv <- defaultErrorHandler defaultDynFlags $ do runGhc (Just libdir) $ do dflags <- getSessionDynFlags setSessionDynFlags dflags target <- guessTarget file Nothing setTargets [target] load LoadAllTargets gr <- getModuleGraph mi <- getModuleInfo $ ms_mod $ head $ gr return $ fromJust $ mi print $ showSDoc $ ppr $ modInfoInstances $ rv print $ showSDoc $ ppr $ modInfoExports $ rv given Test.hs: module Test where hello = "hello" world = "world" one = 1 two = 2 i get this output: $ ./Main ./Test.hs "[]" "[Test.hello, Test.one, Test.two, Test.world]" which is what i expect. My question is, how do manipulate the symbols exported by Test? Is there a way to test the types? lets say i wanted to sum all the numbers and concatenate all the strings in Test.hs, how would i do that?

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