September 2008 - Glasgow-haskell-users

partially applied type synonyms
by Arie Peterson 05 Mar '12

05 Mar '12

Dear list, Is there a good reason that partially applied type synonyms cannot be made instances of classes? - A simple example would be making the identity type 'Id' ("type Id x = x") instance of 'Monad'. This would eliminate the need for some silly occurrences of 'runIdentity', and perhaps narrow the gap between monads and monad transformers. - The reason I complain about this now is a more involved example, where introducing a newtype to work around the restriction is not an option. Well, not as far as I can see now, anyway. Partially applied type synonyms are, in a sense, the anonymous functions at the type level, and one might argue that they deserve the same 'first-class member status' as the lambda at the value level. Kind regards, Arie Peterson

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ANNOUNCE: GHC 6.8.3 Release Candidate
by Ian Lynagh 22 Sep '09

22 Sep '09

We are pleased to announce the Release Candidate phase for GHC 6.8.3. Snapshots beginning with 6.8.2.20080527 are release candidates for 6.8.3 You can download snapshots from here: http://www.haskell.org/ghc/dist/stable/dist/ Right now we have the source bundles: http://www.haskell.org/ghc/dist/stable/dist/ghc-6.8.2.20080527-src.tar.bz2 http://www.haskell.org/ghc/dist/stable/dist/ghc-6.8.2.20080527-src-extralib… Only the first of these is necessary. The "extralibs" package contains various extra packages that are often supplied with GHC - unpack the extralibs tarball on top of the source tree to add them, and they will be included in the build automatically. There is also currently an installer for i386/Windows and binary distributions for x86_64/Linux and i386/Linux. More may appear later. Please test as much as possible; bugs are much cheaper if we find them before the release! We expect to release in a few days, assuming no major issues are discovered. Thanks Ian, on behalf of the GHC team

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Build system idea
by Simon Marlow 10 Jan '09

10 Jan '09

Simon PJ and I had a talk about the build system earlier today, I thought I'd float the idea we discussed (I should admit that the idea was mine, lest Simon PJ think I'm attributing bad ideas to him :-). This is not completely thought through, but I'm pretty sure a solution exists along these lines that would improve things for us. Ok, the starting point is this: - Cabal has code to generate Makefiles. Almost nobody uses it except for the GHC build system. It essentially duplicates the build system for compiling Haskell source (but not for installation, haddocking, registration, configuration, etc.) - Cabal is a library I propose we do this: - Extract the code from Cabal that generates Makefiles, and treat it as part of the GHC build system. Rather than generating a Makefile complete with build rules, we generate a Makefile that just has the package-specific metadata (list of modules, etc.), and put the code to actually build the package in the GHC build system. This means we still get to use 'make', we still get to use the .cabal files as metadata, but the build system is more private to GHC, more extensible, and hopefully more understandable and modifiable. We can express dependencies that Cabal currently doesn't know about. It would let us avoid the current uncomfortable situation where we have to feed all kinds of configuration information from the GHC build system into Cabal - Cabal would be essentially just a mechanism for translating the .cabal file into Makefile bindings and package metadata for ghc-pkg. There will undoubtedly be some sticking points where we have to tradeoff duplicating things from Cabal against re-using parts of Cabal which might require modifying Cabal itself. For instance, we could use Cabal for installation, but that means that our build system has to leave everything in the places that Cabal's installation code expects, so it might be more feasible to do installation ourselves, but that means duplicating parts of Cabal. It will probably mean that we have a tighter dependency on Cabal, because we use it as a library rather than a black box; but hopefully we can keep our branch of Cabal more stable and not have to update it so often. Anyway, this is an idea that I think is interesting. Obviously it needs a lot more fleshing out to be a real proposal, but I'm interested in whether anyone thinks this idea is worth persuing, or whether there are better alternatives. Cheers, Simon

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ghci and ghc -threaded broken with pipes & forking
by John Goerzen 29 Dec '08

29 Dec '08

Hi, I've been hitting my head against a wall for the past couple of days trying to figure out why my shell-like pipeline code kept hanging. I found fd leakage (file descriptors not being closed), which disrupts EOF detection and can lead to deadlocks. I just couldn't find the problem. I finally tried compiling my test with ghc instead of running it in ghci. And poof, it worked fine the first time. I tried asking on #haskell, and got the suggestion that ghci uses -threaded. I tried compiling my test program with ghc -threaded, and again, same deadlock. My program never calls forkIO or forkOS or any other threading code. You can see my test case with: darcs get '--tag=glasgow ml' http://darcs.complete.org/hsh ghc -fglasgow-exts --make -o test2 test2.hs That'll run fine. If you add -threaded, it will hang. Ideas? Thanks, -- John

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Re: SVN binding with Haskell
by Christian Maeder 24 Oct '08

24 Oct '08

Hi, I've install HsSVN (version 0.3.3) using ghc-6.8.3 and Cabal-1.4.0.1, but it was a real pain (under i686 Linux 2.6.22.18-0.2-default #1 SMP) 1. I had to install subversion-devel-1.4.4-30 (of course) 2. configure went through after setting: export CPATH=/usr/include/apr-1:/usr/include/subversion-1 3. building failed with: Program error: <handle>: IO.getContents: protocol error (input contains non-character data - use binary I/O for binary data) because some comments in the sources (i.e. Subversion/FileSystem.hsc) contain funny (japanese?) characters that hsc2hs does not like. (Under Solaris and Mac this was no problem, though.) I used iconv to convert the sources and finally the included HelloWorld example went through. 4. Under Solaris, only apr-1-config and apu-1-config found the proper include path (so I needed to adjust the configure.ac file) 5. The file HsSVN.buildinfo.in has no final newline, so that the last line (containing the ld-options:) is missing in HsSVN.buildinfo after configure! 6. Running the examples under Solaris failed with: -bash-3.1$ ./HelloWorld Creating a repository "repos"... The youngest revision of the repository is 0 Storing a file "/hello" in it... HelloWorld: user error (withSubversion: caught an SvnError: UnknownError 22: Can't set position pointer in file 'repos/db/revs/0': Invalid argument) Cheers Christian Shahzad wrote: > Dear Sir/Madam, > > I am doctoral student and researcher in Technical University Vienna. I > need to manage Subversion client and run SVN commands through > Haskell6.8 , and I need to make that application for ubuntu and Windows, > Can you guide me how to make any API for Haskell to use Subversion. > > I was thinking to use c2hs to make an interface from C++ to haskell but > I could not find that a solution. There is a Package HsSVN but is also > not working. > > Can you please guide me to the solution.. > > Best Regards > > Syed

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ANNOUNCE: GHC 6.10.1 beta
by Ian Lynagh 17 Oct '08

17 Oct '08

We are pleased to announce that the GHC 6.10.0.20080921 snapshot is a beta release of GHC 6.10.1. You can download snapshots from here: http://www.haskell.org/ghc/dist/stable/dist/ Right now we have the source bundles: http://www.haskell.org/ghc/dist/stable/dist/ghc-6.10.0.20080921-src.tar.bz2 http://www.haskell.org/ghc/dist/stable/dist/ghc-6.10.0.20080921-src-extrali… Only the first of these is necessary. The "extralibs" package contains various extra packages that we normally supply with GHC - unpack the extralibs tarball on top of the source tree to add them, and they will be included in the build automatically. There is also currently an installer for i386/Windows, and a binary distribution for x86_64/Linux. More may appear later. There are a couple of known problems with the x86_64/Linux bindist: * It uses libedit.so.0 whereas some distributions (e.g. Debian) only provide libedit.so.2. * It installs utilities like unlit in the wrong place, so compiling literate code won't work. If you install from source then you won't hit either of those problems. Please test as much as possible; bugs are much cheaper if we find them before the release! We hope to have release candidates followed by a release in around 3 weeks time, but of course that may slip if problems are uncovered. Thanks Ian, on behalf of the GHC team

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Is -fvia-C still needed?
by leledumbo 05 Oct '08

05 Oct '08

I notice that speed from code generated by -fasm and -fvia-C isn't significant, furthermore -fvia-C takes longer time. So, why ghc still needs gcc (at least on Windows)? -- View this message in context: http://www.nabble.com/Is--fvia-C-still-needed--tp19663119p19663119.html Sent from the Haskell - Glasgow-haskell-users mailing list archive at Nabble.com.

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GHC on Solaris/SPARC?
by Elliott Slaughter 01 Oct '08

01 Oct '08

Hi, I am having trouble with precompiled binary http://www.haskell.org/ghc/dist/6.8.3/maeder/ghc-6.8.3-sparc-sun-solaris2.t… . My first problem was that the machine is 64-bit SPARC while the binary seems to be 32-bit. Since the dynamically linked GHC binary requires additional .so files to run, any libs which I try to compile on the machine itself run into ELF class incompatibility errors. So I tried installing prebuilt packages from http://sunfreeware.com/, and spent a couple hours grokking the Solaris package system before I figured out how to extract the right files. Now I think I have the right libs installed, but when I try to run GHC, I get this: -bash-3.00$ runhaskell Setup configure ld.so.1: ghc-6.8.3: fatal: relocation error: file /home/.../lib/libncurses.so.5: symbol main: referenced symbol not found (FYI, I got ncurses 5.6 from http://sunfreeware.com/programlistsparc10.html#ncurses.) Any suggestions would be welcome, thanks in advance. -- Elliott Slaughter "Any road followed precisely to its end leads precisely nowhere." - Frank Herbert -- Elliott Slaughter "Any road followed precisely to its end leads precisely nowhere." - Frank Herbert

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Re: ANNOUNCE: GHC 6.10.1 beta
by humasect 30 Sep '08

30 Sep '08

Thank you all. Everything is great now. It was because (Just ghcPath) was not passed into runGhc, and lack of ghc-path. peace and happiness, -lyndon 2008/9/28 Thorkil Naur <naur(a)post11.tele.dk> Hello, > > On Sunday 28 September 2008 19:27, humasect wrote: > > Ah, indeed it does! Then, more about GHC API: > > "Shell: Shell: missing -B<dir> option" > > > > I can't find any information of what this -B is, it is not in GHC sources > or > > anything helpful from google. > > The -B is used from a ghc shell script to identify where the rest of the > GHC > installation resides. An example with a GHC 6.8.2 installed in > $HOME/tn/install/ghc-6.8.2: > > > tn@linux:~> cat tn/install/ghc-6.8.2/bin/ghc > > #!/bin/sh > > GHCBIN=/home/tn/tn/install/ghc-6.8.2/lib/ghc-6.8.2/ghc-6.8.2 > > TOPDIROPT=-B/home/tn/tn/install/ghc-6.8.2/lib/ghc-6.8.2 > > exec $GHCBIN $TOPDIROPT ${1+"$@"} > > tn@linux:~> > > There is likely some designation for this option that I cannot recall. If > it > is documented anywhere, I haven't noticed. > > > ... > > Best regards > Thorkil >

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Re: newSession gone from GHC API
by humasect 29 Sep '08

29 Sep '08

Also to make Located String in the simple way: import SrcLoc L noSrcSpan "-hidir ../build" also make sure to "import MonadUtils" for that version of liftIO. I have converted the graphical/opengl/openal shell for the project I am working on successfully, let me know if you have questions! -lyndon 2008/9/29 Claus Reinke <claus.reinke(a)talk21.com> I just noticed that newSession has been removed from the GHC API. >> Unfortunately, this breaks nearly all examples on the web: >> http://www.haskell.org/haskellwiki/GHC/As_a_library >> http://hackage.haskell.org/trac/ghc/wiki/Commentary/Compiler/API >> Could someone fix those up, to show the new style of interaction? Also >> are the breaking changes to newSession in GHC 6.10, or only in GHC Head? >> > > Thomas said he was working on a conversion guide, but > delayed by travelling: > > http://www.haskell.org/pipermail/cvs-ghc/2008-September/045361.html > > Meanwhile, since you're somewhat familar with haddock, his > patches to port haddock to the new api may help (I used them > to figure out where to look for more info;). Or, if you prefer > smaller examples, have a look at > > http://www.cs.kent.ac.uk/~cr3/toolbox/haskell/syb-utils/examples/GhcApiSybT… > > which I patched recently (diff below). Mostly, you'll be looking for > runGhc, dropping session parameters, changing dynamic flags from > String to Located String, and splitting checkModule into separate > phases (there's a class that simplifies access via the old record selector > functions). Possibly other small things, like using liftIO to > do IO in the Ghc monads. > > Hth, > Claus > > $ darcs changes -v -p 'new Ghc Api' | sed 's/\[_.._\]\[_._\]$//' > diffing dir... > Mon Sep 22 20:01:02 GMT Daylight Time 2008 claus.reinke(a)talk21.com > * adapt example to new Ghc Api > { > hunk ./examples/GhcApiSybTesting.hs 15 > +import SrcLoc > +import MonadUtils > hunk ./examples/GhcApiSybTesting.hs 35 > -main = defaultErrorHandler defaultDynFlags $ do > - s <- newSession (Just libdir) > - flags <- getSessionDynFlags s > - (flags,_,_) <- parseDynamicFlags flags ["-package ghc"] > +main = defaultErrorHandler defaultDynFlags $ > + runGhc (Just libdir) $ do > + flags <- getSessionDynFlags > + (flags,_,_) <- parseDynamicFlags flags [noLoc "-package ghc"] > hunk ./examples/GhcApiSybTesting.hs 40 > - setSessionDynFlags s flags{ hscTarget=HscInterpreted } > - addTarget s =<< guessTarget source Nothing > - load s LoadAllTargets > - unqual <- getPrintUnqual s > + setSessionDynFlags flags{ hscTarget=HscInterpreted } > + addTarget =<< guessTarget source Nothing > + load LoadAllTargets > + unqual <- getPrintUnqual > + {- > hunk ./examples/GhcApiSybTesting.hs 50 > + -} > + tcm <- typecheckModule =<< parseModule (mkModuleName modName) > + doSomething unqual tcm > hunk ./examples/GhcApiSybTesting.hs 63 > - doSomething unqual cm = do > - let parsed = parsedSource cm > - renamed = renamedSource cm > - typechecked = typecheckedSource cm > + doSomething unqual tcm = liftIO $ do > + let parsed = parsedSource tcm > + renamed = renamedSource tcm > + typechecked = typecheckedSource tcm > hunk ./examples/GhcApiSybTesting.hs 84 > - maybe (putStrLn "no typechecked source") > - (printForUser stdout unqual . shown TypeChecker) > typechecked > + printForUser stdout unqual $ shown TypeChecker typechecked > > } > > _______________________________________________ > Glasgow-haskell-users mailing list > Glasgow-haskell-users(a)haskell.org > http://www.haskell.org/mailman/listinfo/glasgow-haskell-users >

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