September 2009 - Haskell-Cafe

Re: cabal: : openFile: does not exist (No such file or directory)
by Thomas Hartman 03 Sep '09

03 Sep '09

cabal -v3 update will give you a more verbose version of what is going wrong. cabal --help regrettably, cabal --help doesn't tell you this but there is always the man page I suppose. 2009/7/16 Tony Hannan <tonyhannan2(a)gmail.com>: > Hello, > > I'm on Ubuntu 8.10. > I installed ghc 6.10.4 (from binary package: > ghc-6.10.4-i386-unknown-linux-n.tar.bz2). > I installed haskell-platform-2009.2.0.1 (from source package: > haskell-platform-2009.2.0.1.tar.gz). It contains cabal-install-0.6.2. > > Then when I run "cabal update", I get the following error: > cabal: : openFile: does not exist (No such file or directory) > > Any ideas? > > Thanks, > Tony > > _______________________________________________ > Libraries mailing list > Libraries(a)haskell.org > http://www.haskell.org/mailman/listinfo/libraries > >

6 11

cannot build greencard
by mf-hcafe-15c311f0c＠etc-network.de 02 Sep '09

02 Sep '09

hi, i am stuck with a linker error in greencard, and haven't found anything online, so i am addressing you for fresh ideas. as soon as i get this sorted out, i will try to turn the answer into a patch that you can consider for the next release. SYMPTOMS: greencard 3.0.3 and 3.01 do not compile with ghc-6.8 (debian lenny package) and 6.10 (darcs copy, checked out yesterday). here is what happens: 4 (0) 19:27:19 mf@yoyo:/tmp2 $ tar xvpzf greencard-3.0.3.tar.gz greencard-3.0.3/ greencard-3.0.3/ANNOUNCE greencard-3.0.3/dist/ greencard-3.0.3/dist/build/ greencard-3.0.3/dist/build/greencard/ greencard-3.0.3/dist/build/greencard/greencard-tmp/ greencard-3.0.3/dist/build/greencard/greencard-tmp/Parse.hs greencard-3.0.3/examples/ greencard-3.0.3/examples/Gdbm/ greencard-3.0.3/examples/Gdbm/diffs greencard-3.0.3/examples/Gdbm/Gdbm.gc greencard-3.0.3/examples/Gdbm/gdbmplus.h greencard-3.0.3/examples/Gdbm/Main.hs greencard-3.0.3/examples/Gdbm/Makefile greencard-3.0.3/examples/Gdbm/README greencard-3.0.3/examples/Makefile greencard-3.0.3/examples/world/ greencard-3.0.3/examples/world/Main.hs greencard-3.0.3/examples/world/Makedefs.ghc greencard-3.0.3/examples/world/Makedeps greencard-3.0.3/examples/world/Makefile.ghc-linux greencard-3.0.3/examples/world/Makefile.ghc-win32 greencard-3.0.3/examples/world/Makefile.hugs-linux greencard-3.0.3/examples/world/Makefile.hugs-win32 greencard-3.0.3/examples/world/README.txt greencard-3.0.3/examples/world/World.gc greencard-3.0.3/greencard.cabal greencard-3.0.3/INSTALL greencard-3.0.3/lib/ greencard-3.0.3/lib/Foreign/ greencard-3.0.3/lib/Foreign/GreenCard.hs greencard-3.0.3/lib/GreenCard.gc greencard-3.0.3/lib/Makefile greencard-3.0.3/lib/package.conf.in greencard-3.0.3/LICENSE greencard-3.0.3/Makefile greencard-3.0.3/README greencard-3.0.3/Setup.hs greencard-3.0.3/src/ greencard-3.0.3/src/Casm.lhs greencard-3.0.3/src/Decl.lhs greencard-3.0.3/src/DIS.lhs greencard-3.0.3/src/ErrMonad.lhs greencard-3.0.3/src/ErrorHook.c greencard-3.0.3/src/FillIn.lhs greencard-3.0.3/src/FillInMonad.lhs greencard-3.0.3/src/GCToken.lhs greencard-3.0.3/src/greencard.ghc.in greencard-3.0.3/src/greencard.hugs.in greencard-3.0.3/src/GreenCard.lhs greencard-3.0.3/src/Lex.lhs greencard-3.0.3/src/LexM.lhs greencard-3.0.3/src/ListUtils.lhs greencard-3.0.3/src/Makefile greencard-3.0.3/src/MarshallMonad.lhs greencard-3.0.3/src/Name.lhs greencard-3.0.3/src/NameSupply.lhs greencard-3.0.3/src/Package.lhs greencard-3.0.3/src/Package.lhs.in greencard-3.0.3/src/Parse.ly greencard-3.0.3/src/PrettyUtils.lhs greencard-3.0.3/src/Proc.lhs greencard-3.0.3/src/Process.lhs greencard-3.0.3/src/Target.lhs greencard-3.0.3/src/Type.lhs 5 (0) 19:27:22 mf@yoyo:/tmp2 $ cd greencard-3.0.3 6 (0) 19:27:24 mf@yoyo:/tmp2/greencard-3.0.3 $ make prefix=/tmp2/ make[1]: Entering directory `/hime/tmp2/greencard-3.0.3/src' happy Parse.ly unused terminals: 1 rm -f .depend touch .depend ghc -M -optdep-f -optdep.depend -optdep-xFiniteMap -optdep-xPretty -recomp -O -fglasgow-exts Casm.lhs DIS.lhs Decl.lhs ErrMonad.lhs FillIn.lhs FillInMonad.lhs GCToken.lhs GreenCard.lhs Lex.lhs LexM.lhs ListUtils.lhs MarshallMonad.lhs Name.lhs NameSupply.lhs Package.lhs PrettyUtils.lhs Proc.lhs Process.lhs Target.lhs Type.lhs Parse.hs make[1]: Leaving directory `/hime/tmp2/greencard-3.0.3/src' make[1]: Entering directory `/hime/tmp2/greencard-3.0.3/src' ghc -recomp -O -fglasgow-exts -c Target.lhs -o Target.o ghc -recomp -O -fglasgow-exts -c PrettyUtils.lhs -o PrettyUtils.o ghc -recomp -O -fglasgow-exts -c Casm.lhs -o Casm.o Casm.lhs:544:1: Warning: Pattern match(es) are overlapped In a case alternative: _ -> ... Casm.lhs:577:1: Warning: Pattern match(es) are overlapped In a case alternative: _ -> ... Casm.lhs:616:4: Warning: Pattern match(es) are overlapped In a case alternative: _ -> ... Casm.lhs:631:5: Warning: Pattern match(es) are overlapped In a case alternative: _ -> ... ghc -recomp -O -fglasgow-exts -c ListUtils.lhs -o ListUtils.o ghc -recomp -O -fglasgow-exts -c ErrMonad.lhs -o ErrMonad.o ghc -recomp -O -fglasgow-exts -c Name.lhs -o Name.o ghc -recomp -O -fglasgow-exts -c DIS.lhs -o DIS.o ghc -recomp -O -fglasgow-exts -c Type.lhs -o Type.o ghc -recomp -O -fglasgow-exts -c Decl.lhs -o Decl.o ghc -recomp -O -fglasgow-exts -c FillInMonad.lhs -o FillInMonad.o ghc -recomp -O -fglasgow-exts -c NameSupply.lhs -o NameSupply.o ghc -recomp -O -fglasgow-exts -c FillIn.lhs -o FillIn.o ghc -recomp -O -fglasgow-exts -c GCToken.lhs -o GCToken.o ghc -recomp -O -fglasgow-exts -c MarshallMonad.lhs -o MarshallMonad.o ghc -recomp -O -fglasgow-exts -c Proc.lhs -o Proc.o ghc -recomp -O -fglasgow-exts -c LexM.lhs -o LexM.o ghc -recomp -O -fglasgow-exts -c Lex.lhs -o Lex.o ghc -recomp -O -fglasgow-exts -Onot -c Parse.hs -o Parse.o Parse.hs:1733:1: Warning: Pattern match(es) are overlapped In a case alternative: _ -> ... ghc -recomp -O -fglasgow-exts -c Process.lhs -o Process.o ghc -recomp -O -fglasgow-exts -c Package.lhs -o Package.o ghc -recomp -O -fglasgow-exts -cpp -DBEGIN_GHC_ONLY='-}' -DEND_GHC_ONLY='{-' -DBEGIN_NOT_FOR_GHC='{-' -DEND_NOT_FOR_GHC='-}' -DPURE_WIN32=0 -c GreenCard.lhs -o GreenCard.o ghc -c ErrorHook.c -o ErrorHook.o ghc -recomp -O -fglasgow-exts -o greencard-bin Casm.o DIS.o Decl.o ErrMonad.o FillIn.o FillInMonad.o GCToken.o GreenCard.o Lex.o LexM.o ListUtils.o MarshallMonad.o Name.o NameSupply.o Package.o PrettyUtils.o Proc.o Process.o Target.o Type.o Parse.o ErrorHook.o Casm.o: In function `s201_info': (.text+0x168): undefined reference to `prettyzm1zi0zi0zi0_TextziPrettyPrintziHughesPJ_Str_con_info' Casm.o: In function `s201_info': (.text+0x17b): undefined reference to `prettyzm1zi0zi0zi0_TextziPrettyPrintziHughesPJ_TextBeside_con_info' Casm.o: In function `s201_info': (.text+0x19d): undefined reference to `prettyzm1zi0zi0zi0_TextziPrettyPrintziHughesPJ_Empty_closure' Casm.o: In function `s201_info': (.text+0x1b7): undefined reference to `prettyzm1zi0zi0zi0_TextziPrettyPrintziHughesPJ_Str_con_info' Casm.o: In function `s201_info': (.text+0x1ca): undefined reference to `prettyzm1zi0zi0zi0_TextziPrettyPrintziHughesPJ_TextBeside_con_info' Casm.o: In function `s201_info': (.text+0x1e9): undefined reference to `prettyzm1zi0zi0zi0_TextziPrettyPrintziHughesPJ_Empty_closure' Casm.o: In function `s201_info': (.text+0x1f0): undefined reference to `prettyzm1zi0zi0zi0_TextziPrettyPrintziHughesPJ_Beside_con_info' [... these continue for every object file on the command line; a bit over 2000 message of the same type in total...] Type.o: In function `sBv_info': (.text+0x1b2b): undefined reference to `prettyzm1zi0zi0zi0_TextziPrettyPrintziHughesPJ_Beside_con_info' Type.o: In function `sZT_info': (.text+0x1ed3): undefined reference to `__stginit_prettyzm1zi0zi0zi0_TextziPrettyPrint_' Type.o: In function `sBb_info': (.text+0x1988): undefined reference to `prettyzm1zi0zi0zi0_TextziPrettyPrintziHughesPJ_go6_info' Type.o: In function `sBf_info': (.text+0x1a12): undefined reference to `prettyzm1zi0zi0zi0_TextziPrettyPrintziHughesPJ_go6_info' Type.o: In function `sZU_info': (.text+0x1b96): undefined reference to `prettyzm1zi0zi0zi0_TextziPrettyPrintziHughesPJ_text_info' Type.o: In function `rvv_closure': (.data+0x8): undefined reference to `prettyzm1zi0zi0zi0_TextziPrettyPrintziHughesPJ_Chr_static_info' Type.o: In function `rvH_closure': (.data+0x64): undefined reference to `prettyzm1zi0zi0zi0_TextziPrettyPrintziHughesPJ_TextBeside_static_info' Type.o: In function `rvH_closure': (.data+0x6c): undefined reference to `prettyzm1zi0zi0zi0_TextziPrettyPrintziHughesPJ_lvl3_closure' Type.o: In function `rvH_closure': (.data+0x70): undefined reference to `prettyzm1zi0zi0zi0_TextziPrettyPrintziHughesPJ_Empty_closure' Type.o: In function `rvN_closure': (.data+0xb0): undefined reference to `prettyzm1zi0zi0zi0_TextziPrettyPrintziHughesPJ_Str_static_info' collect2: ld returned 1 exit status make[1]: *** [greencard-bin] Error 1 make[1]: Leaving directory `/hime/tmp2/greencard-3.0.3/src' make[1]: Entering directory `/hime/tmp2/greencard-3.0.3/lib' ghc -package-name greencard -cpp -fglasgow-exts -fno-prune-tydecls -c Foreign/GreenCard.hs -o Foreign/GreenCard.o -hisuf hi ghc-6.8.2: unrecognised flags: -fno-prune-tydecls Usage: For basic information, try the `--help' option. make[1]: *** [Foreign/GreenCard.o] Error 1 make[1]: Leaving directory `/hime/tmp2/greencard-3.0.3/lib' make[1]: Entering directory `/hime/tmp2/greencard-3.0.3/src' make[1]: Nothing to be done for `all'. make[1]: Leaving directory `/hime/tmp2/greencard-3.0.3/src' make[1]: Entering directory `/hime/tmp2/greencard-3.0.3/lib' ghc -package-name greencard -cpp -fglasgow-exts -fno-prune-tydecls -prof -c Foreign/GreenCard.hs -o Foreign/GreenCard.p_o -hisuf p_hi ghc-6.8.2: unrecognised flags: -fno-prune-tydecls Usage: For basic information, try the `--help' option. make[1]: *** [Foreign/GreenCard.p_o] Error 1 make[1]: Leaving directory `/hime/tmp2/greencard-3.0.3/lib' make: *** [all] Error 2 the errors about no-prune-tydecls are easy enough to fix: $ diff -r greencard-3.0.3{,-patched} diff -r greencard-3.0.3/examples/Gdbm/Makefile greencard-3.0.3-patched/examples/Gdbm/Makefile 28d27 < HC_OPTS += -fno-prune-tydecls diff -r greencard-3.0.3/lib/Makefile greencard-3.0.3-patched/lib/Makefile 6c6 < GHC_OPTS = -cpp -fglasgow-exts -fno-prune-tydecls --- > GHC_OPTS = -cpp -fglasgow-exts $ this helps, but the linker errors are unrealted, and i don't know what to make of them. (I guess I should study how ghc generates C code at this point? it does feel like something obvious...) thanks, cheers, matthias

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Can GHC produce dylib on MacOSX/Intel?
by Pavel Perikov 02 Sep '09

02 Sep '09

Is it possible? Is it possible with binary distribution? Regards, Pavel

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Documentation on the internals of Hugs
by KwangYul Seo 02 Sep '09

02 Sep '09

Hello, I want to study the internals lof Hugs, but the only document I got is: The implementation of the Gofer functional programming system http://web.cecs.pdx.edu/~mpj/pubs/goferimp.html I see Gofer is the predecessor of Hugs, but I am not sure how much the code base has been changed since then. Are there more recent documents on the internals of Hugs? Regards, Kwang Yul Seo

1 0

Cleaning up stable names?
by Peter Verswyvelen 02 Sep '09

02 Sep '09

>From the documentation, I don't think I grasp how stable names work. >From the docs: "There is no deRefStableName operation. You can't get back from a stable name to the original Haskell object. The reason for this is that the existence of a stable name for an object does not guarantee the existence of the object itself; it can still be garbage collected." >From this I can conclude that stable names behave a bit like weak pointers. However, suppose I have a hash table of these stable names. How can I remove the redundant stable names from the table? I mean removing stable names that refer to an object that is garbage collected? I don't see any function for checking that (e.g. isStableNameTargetAlive or something) Thanks, Peter

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Slow IO?
by Steve 02 Sep '09

02 Sep '09

Hi, I'm tackling a Sphere Online Judge tutorial question where it tests how fast you can process input data. You need to achieve at least 2.5MB of input data per second at runtime (on an old machine running ghc 6.6.1). This is probably close to the limit of Haskell's ability. https://www.spoj.pl/problems/INTEST/ I can see that 24 haskell programmers have solved it, but most are very close to the 8 secs limit (and 6/24 are even over the limit!). Here's my code. It fails with a "time limit exceeded" error. (I think it would calculate the correct result, eventually). module Main where import qualified Data.List as DLi import qualified System.IO as SIO main :: IO () main = do line1 <- SIO.hGetLine SIO.stdin let k = read $ words line1 !! 1 s <- SIO.hGetContents SIO.stdin print $ count s k count :: String -> Int -> Int count s k = DLi.foldl' foldFunc 0 (map read $ words s) where foldFunc :: Int -> Int -> Int foldFunc a b | mod b k == 0 = a+1 | otherwise = a I tried using Data.ByteString but then found that 'read' needs a String, not a ByteString. I tried using buffered IO, but it did not make any difference. Any suggestions on how to speed it up? Regards, Steve

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Question about Lazy.IO
by staafmeister 02 Sep '09

02 Sep '09

Hi, I've been wondering about Lazy IO for a while. Suppose we have a program like main = interact (unlines . somefunction . lines) then somefunction is a pure function. With the semantic interpretation of: given a input list return an output list. However I, the user, can change my input depending on the output of this function. Now in simple cases like this, this will not be a problem. But suppose you are reading and writing to a file. Now the result of pure functions become dependent on the order of execution, breaking (I think) referential transparency. Am I wrong here or how could you prove that Lazy IO is consistent nonetheless? Greetings, Gerben -- View this message in context: http://www.nabble.com/Question-about-Lazy.IO-tp25236848p25236848.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.

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Re: [Haskell-cafe] GUI library
by Job Vranish 01 Sep '09

01 Sep '09

If you're already used to C++ Qt and PyQt, qtHaskell should be relatively straightforward (though probably with a few gotchas). You could download qtHaskell and look at the examples to get an idea for the feel of it. If you're already used to Qt they should look familiar. Subclassing _is_ done a little weird: First you declare a dummy datatype: data MyQPushButton = MyQPushButton And then you use the qSubClass function: myQPushButton :: String -> IO (QPushButton MyQPushButton) myQPushButton s = qSubClass $ qPushButton1 s The type signature here is necessary. It's the only thing that forces the new (QPushButton a) to be a QPushButton MyQPushButton. Then you can use your subclassed buttons like so: main :: IO () main = do app <- qApplication dialog <- qDialog button1 <- myQPushButton "Click for Stuff" qObject_connectSlot1 button1 "clicked()" button1 "click()" $ on_pbutton_clicked dialog mainLayout <- qVBoxLayout qLayout_addWidget mainLayout button1 qWidget_setLayout dialog mainLayout qWidget_setWindowTitle dialog "Stuff Test" ok <- qDialog_exec dialog return() on_pbutton_clicked :: QDialog () -> QPushButton MyQPushButton -> IO () on_pbutton_clicked _dlg _this = do mb <- qMessageBox1 _dlg qMessageBox_setText mb $ "Stuff" qWidget_show mb return () Hmmm, though it doesn't look like you can currently overload methods of your parent class, usually you don't need too though as you can just tie into a signal (so you still can do things like paint). Though I'm kinda suprised I didn't notice this before, I'll have to email the guy and see if this is actually an issue. Also, qtHaskell doesn't fully support all the Qt widgets (though it covers most of them) but there is a new version coming out soon that should be more complete. Overall qtHaskell has served my perposes well. There is also a good listing of GUI toolkits for Haskell at http://www.haskell.org/haskellwiki/Applications_and_libraries/GUI_libraries - Job On Tue, Sep 1, 2009 at 1:49 AM, Michael Mossey <mpm(a)alumni.caltech.edu>wrote: > Thanks for the info. Interesting. I'm already familiar with C++ Qt and also > PyQt. I am also a fan of Qt. > > However, as a beginner to Haskell, I want to be sure I don't get myself > into trouble. I hope that qtHaskell is straightforward. > > Qt depends on deriving user classes. How is this handled in qtHaskell? > > Thanks, > > -Mike > > > Job Vranish wrote: > >> I recommend qtHaskell. >> I am a big fan of Qt in general. It has good documentation and extensive >> examples, is very well designed, and has a good license. I'd even say the >> C++ version is good choice for beginners (certainly easier to understand/use >> than say GTK). >> The qtHaskell bindings are also pretty good. The documentation and >> examples are not as extensive, but you can usually use the C++ documentation >> to fill in the gaps. >> Being already familiar with C++ Qt, using qtHaskell was a snap. However, >> if you're unfamiliar with both Qt and Haskell it will probably be confusing >> at first. Though I'd bet money the GTK bindings aren't any better in that >> regard. >> I'd still say you'd be more productive with qtHaskell in the long run. >> >> - Job >> >> >> On Sat, Aug 29, 2009 at 11:03 AM, Michael Mossey <mpm(a)alumni.caltech.edu<mailto: >> mpm(a)alumni.caltech.edu>> wrote: >> >> I want to choose a GUI library for my project. Some background: I'm >> a beginner to functional programming and have been working through >> Haskell books for a few months now. I'm not just learning Haskell >> for s**ts and giggles; my purpose is to write >> music-composition-related code; in particular, I want to write a >> graphical musical score editor. (Why write my own editor, you may >> ask? Because I want to fully integrate it with >> computer-assisted-composition algorithms that I plan to write, also >> in Haskell.) I decided to use Haskell for its great features as a >> functional programming language. >> >> Regarding a choice of GUI library, I want these factors: >> >> - it needs to provide at a minimum a drawing surface, a place I can >> draw lines and insert characters, in addition to all the standard >> widgets and layout capabilities we have to come to expect from a GUI >> library. >> >> - This is a Windows application. >> >> - it needs to be non-confusing for an intermediate-beginner >> Haskeller. Hopefully good documentation and examples will exist on >> the web. >> >> - It might be nice to have advanced graphics capability such as Qt >> provides, things like antialiasied shapes, and a canvas with >> efficient refresh (refereshes only the area that was exposed, and if >> your canvas items are only primitives, it can do refreshes from >> within C++ (no need to touch your Haskell code at all). However I'm >> wondering if qtHaskell fits my criteria "well-documented" and "lots >> of examples aimed at beginners". >> >> Thanks, >> Mike >> _______________________________________________ >> Haskell-Cafe mailing list >> Haskell-Cafe(a)haskell.org <mailto:Haskell-Cafe@haskell.org> >> http://www.haskell.org/mailman/listinfo/haskell-cafe >> >> >>

1 0

GUI library
by Michael Mossey 01 Sep '09

01 Sep '09

I want to choose a GUI library for my project. Some background: I'm a beginner to functional programming and have been working through Haskell books for a few months now. I'm not just learning Haskell for s**ts and giggles; my purpose is to write music-composition-related code; in particular, I want to write a graphical musical score editor. (Why write my own editor, you may ask? Because I want to fully integrate it with computer-assisted-composition algorithms that I plan to write, also in Haskell.) I decided to use Haskell for its great features as a functional programming language. Regarding a choice of GUI library, I want these factors: - it needs to provide at a minimum a drawing surface, a place I can draw lines and insert characters, in addition to all the standard widgets and layout capabilities we have to come to expect from a GUI library. - This is a Windows application. - it needs to be non-confusing for an intermediate-beginner Haskeller. Hopefully good documentation and examples will exist on the web. - It might be nice to have advanced graphics capability such as Qt provides, things like antialiasied shapes, and a canvas with efficient refresh (refereshes only the area that was exposed, and if your canvas items are only primitives, it can do refreshes from within C++ (no need to touch your Haskell code at all). However I'm wondering if qtHaskell fits my criteria "well-documented" and "lots of examples aimed at beginners". Thanks, Mike

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Problems installing documentation and sources using Cabal on Mac OSX
by Colin Adams 01 Sep '09

01 Sep '09

I noticed today on the train (no internet connection!) that the documentation for packages I had installed with cabal was missing, and that there was no source in .cabal/packages for them. Now I'm in the offiice, I tried --reinstall --enable-documentation. There was a warning about haddock and ghc version mismatch (so much for the haskell platform install), so I did a --reinstall of haddock. Now the message I see is: cabal: can't find source for module Paths_happstack_server (happstack_server is the first package I'm trying to reinstall to get docs). So I think the documentation failure is because haddock can't find the source code (nor can I), but I don't know why there is no source installed in .cabal/packages - what should I do to further track this problem down? -- Colin Adams Preston, Lancashire, ENGLAND

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