September 2009 - 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

3 2

Three patches for cabal
by Niklas Broberg 09 Nov '09

09 Nov '09

(Trying again since my previous patches were too big for the list.) While doing a survey[1] of the extensions registered with Cabal, I came across two warts in the list of constructors, and one constructor that should be deprecated. First there's the constructor called TransformListComp, which should really be named GeneralizedListComp, since the constructor should describe the extension and not the implementation scheme. Second there's the constructor NoMonoPatBinds, which actually describes the default Haskell 98 behavior, even if GHC has a different default. It's GHC's behavior that is the extension, so the constructor in cabal should really be named MonoPatBinds. Also, the PatternSignatures constructor has been deprecated in GHC and superceded by ScopedTypeVariables. The attached patches (three in one file) adds the proposed new constructors, deprecates the old ones, and adds documentation. Cheers, /Niklas

8 15

Snow Leopard GHC
by Barney Stratford 08 Oct '09

08 Oct '09

I've been trying to get GHC working for x86_64 on Snow Leopard, with a certain amount of success, but have got stuck. Maybe one of you could point me in the right direction. I now have a working compiler, but the linker in the runtime system seems to be missing some stuff. Specifically, in rts/Linker.c, there are references to X86_64_RELOC_UNSIGNED, X86_64_RELOC_SIGNED and so on, but it simply barfs when faced with a X86_64_RELOC_SIGNED_1 etc. I'd thought it would be a matter of adding a few lines of code, but everything I've tried has ended in tears. Trouble is, none of the documentation mentions X86_64_RELOC_SIGNED_1, although it does appear in C headers. It occurs only rarely in source examples, and it really isn't clear to me how I should proceed. Any ideas? Cheers, Barney.

4 14

Malformed class assertion with GHCi's output (a -> a ~ T a)
by Sean Leather 03 Oct '09

03 Oct '09

I queried (:t) the type of something in GHCi, and it told me the value should have the constraint (a -> a ~ T a) among others. When I tried to use this in code, I got a "malformed class assertion." So, I put parentheses around the function type, ((a -> a) ~ T a), and everybody is happy again. Is there something off about the precedence of (~) vs. (->)? Should GHCi print the parentheses? I'm using GHC 6.10.1, so this might already be fixed. Regards, Sean

3 2

Re: [Haskell-cafe] Ghci dynamic linking (Was: C++ libraries and GHCI)
by Max Bolingbroke 02 Oct '09

02 Oct '09

(Moving to ghc-users) I'd never seen V in nm output before: """ The symbol is a weak object. When a weak defined symbol is linked with a normal defined symbol, the normal defined symbol is used with no error. When a weak undefined symbol is linked and the symbol is not defined, the value of the weak symbol becomes zero with no error. On some systems, uppercase indicates that a default value has been specified. """" Perhaps support needs to be added for this symbol type to the GHCi dynamic linker? (It would work in compiled programs b/c we call down to the system static linker in that case). Cheers, Max 2009/9/29 Paolo Losi <paolo.losi(a)gmail.com>: > Hi all, > > I would really appreciate if anyone could > give a look to the following problem. > > Thanks in advance!!! > Paolo > > > ---------- Forwarded message ---------- > From: Paolo Losi <paolo.losi(a)gmail.com> > Date: Mon, Sep 14, 2009 at 10:33 AM > Subject: C++ libraries and GHCI > To: glasgow-haskell-users(a)haskell.org > > > Hi all, > > I'm working on a tentative implementation of haskell binding to libsvm [1]: > > http://hackage.haskell.org/package/HSvm > > The package includes libsvm C++ sources. > While it works perfectly with ghc --make (try to install the package and > compile http://bitbucket.org/pao/hsvm/raw/6cf7ca91f1e5/test/test.hs) > it fails with ghci: > > (hsvm)(env)paolo@moltrasio:~/trash$ ghci test.hs > GHCi, version 6.10.4: http://www.haskell.org/ghc/ :? for help > Loading package ghc-prim ... linking ... done. > Loading package integer ... linking ... done. > Loading package base ... linking ... done. > Ok, modules loaded: Main. > Prelude Main> main > Loading package syb ... linking ... done. > Loading package array-0.2.0.0 ... linking ... done. > Loading package containers-0.2.0.1 ... linking ... done. > Loading package HSvm-0.1.0.2.89 ... linking ... <interactive>: > /home/paolo/trash/hsvm/lib/HSvm-0.1.0.2.89/ghc-6.10.4/HSHSvm-0.1.0.2.89.o: > unknown symbol `_ZTV6Kernel' > ghc: unable to load package `HSvm-0.1.0.2.89' > > Please note that the symbol is available in libHSHSvm-0.1.0.2.89.a > > $ nm HSHSvm-0.1.0.2.89.o |grep _ZTV6Kernel > 00000000 V _ZTV6Kernel > $ nm libHSHSvm-0.1.0.2.89.a |grep _ZTV6Kernel > 00000000 V _ZTV6Kernel > > Can anyone give a look to the problem? > > Thanks > Paolo > > [1] http://www.csie.ntu.edu.tw/~cjlin/libsvm/ > > > > -- > Paolo Losi > e-mail: paolo(a)enuan.com > mob: +39 348 7705261 > > ENUAN Srl > Via XX Settembre, 12 - 29100 Piacenza > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > >

2 1

which difference...
by Luca Ciciriello 30 Sep '09

30 Sep '09

Hi all. I've recently changed my home machine (MacOS X 10.5.8 intel) and I've installed the GHC 6.10.4 using the pakage: GHC-6.10.4-i386.pkg. All works fine and I can continue all my research projects on my new machine. Then I've noticed that exists another kind of installation using the package: haskell-platform-2009.2.0.2-i386.dmg. What diferences exists between these two pakages? Am I missing something using the first pakage instead using the dmg distribution? Thanks in advance for any answer. Luca. Upgrade to Internet Explorer 8 Optimised for MSN. Download Now _________________________________________________________________ With Windows Live, you can organise, edit, and share your photos. http://clk.atdmt.com/UKM/go/134665338/direct/01/

2 1

Intel's Concurrent Collections for Haskell
by Don Stewart 29 Sep '09

29 Sep '09

http://softtalkblog.wordpress.com/2009/09/29/more-about-haskell-and-intel-c… Intel involved in work to port Concurrent Collections to Haskell. Might be interesting for benchmarks on 6.12 -- Don

1 0

Re: [Haskell-cafe] Status of GHC as a Cross Compiler
by Donnie Jones 24 Sep '09

24 Sep '09

Hello John, glasgow-haskell-users is a more appropriate list... http://www.haskell.org/mailman/listinfo/glasgow-haskell-users I went ahead and cc'd your message to the list. Any replies please include John's email address as I don't think he is subscribed to the list. Hope that helps... -- Donnie Jones On Wed, Sep 23, 2009 at 1:50 PM, John Van Enk <vanenkj(a)gmail.com> wrote: > Hi, > > This may be more appropriate for a different list, but I'm having a hard > time figuring out whether or not we're getting a cross compiler in 6.12 or > not. Can some one point me to the correct place in Traq to find this > information? > > /jve > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > >

2 1

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

8 13

How to solve ghc-stage2: mkTextEncoding: invalid argument (Invalid argument) issue.
by Karel Gardas 21 Sep '09

21 Sep '09

Hello, recently I've found out that my solaris-based GHC buildbot is completely unusable since it always (when it get to, which means it does not fail with usual magic number mismatch: old/corrupt interface file?) fails with: "inplace/bin/ghc-stage2" -H32m -O -DNEW_GHC_LAYOUT -hide-all-packages -i -iutils/haddock/src -iutils/haddock/dist/build -iutils/haddock/dist/build/autogen -Iutils/haddock/dist/build -Iutils/haddock/dist/build/autogen -optP-DIN_GHC_TREE -optP-include -optPutils/haddock/dist/build/autogen/cabal_macros.h -package Cabal-1.7.4 -package array-0.2.0.1 -package base-4.2.0.0 -package containers-0.2.0.1 -package directory-1.0.0.2 -package filepath-1.1.0.1 -package ghc-6.11.20090915 -package pretty-1.0.1.0 -funbox-strict-fields -O2 -Wall -XForeignFunctionInterface -XCPP -XPatternGuards -XDeriveDataTypeable -XScopedTypeVariables -XMagicHash -odir utils/haddock/dist/build -hidir utils/haddock/dist/build -stubdir utils/haddock/dist/build -hisuf hi -osuf o -hcsuf hc -c utils/haddock/src/Haddock/GhcUtils.hs -o utils/haddock/dist/build/Haddock/GhcUtils.o ghc-stage2: mkTextEncoding: invalid argument (Invalid argument) make[1]: *** [utils/haddock/dist/build/Haddock/GhcUtils.o] Error 1 make: *** [all] Error 2 I've even tried to update my building GHC from 6.8.3 to 6.10.4, but it still does not help. Since I would really like to resurrect my GHC buildbot, do you have any idea how to fix this issue? Thanks, Karel PS: for reference, please have a look at http://darcs.haskell.org/buildbot/all/builders/kgardas%20head

5 9