May 2009 - Libraries - Haskell.org

2009.2.1: version freeze for Haskell Platform approaching on Monday
by Don Stewart 16 May '09

16 May '09

According to our release timetable, the last chance to propose bug fix version bumps for 2009.1.0 is Monday: http://trac.haskell.org/haskell-platform/wiki/ReleaseTimetable In particular, I think this affects 'network', where a number of bugs reported against the last platform have been repaired. Please ensure that, as maintainer for one of the 2009.2.x series of packages, any bug fixes are in place by Monday, or they'll be bumped to the next platform release. For a full list of packages distributed with the 2009.2.x series of the platform, see: http://trac.haskell.org/haskell-platform/wiki/2009.2.0 And please continue to propose packages for the next major release, via the bug tracker (and discussion on libraries@) -- Don

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RE: [Haskell-cafe] Removing mtl from the Haskell Platform
by roconnor＠theorem.ca 15 May '09

15 May '09

On Wed, 13 May 2009, Sittampalam, Ganesh wrote: > We've discussed replacing it with transformers+monads-fd+an mtl > compatiblity layer on libraries@. Ross and I plan to propose doing this > for the second release of the platform - it's not fair to disrupt the > first release at this stage. > > transformers+monads-fd is quite a small evolution over mtl - it factors > out the fundeps into a separate package, tightens up some of the class > constraints, and makes State = StateT Identity etc rather than a > separate type. Even this breaks a few packages, but doing anything more > substantial would be quite disruptive. That's not to say that we > shouldn't do it, though. > > I guess the libraries@ list will continue to be the place that such > decisions get made, but I think it's a bit up in the air at the moment. Have you make a trac ticket for your proposal? -- Russell O'Connor <http://r6.ca/> ``All talk about `theft,''' the general counsel of the American Graphophone Company wrote, ``is the merest claptrap, for there exists no property in ideas musical, literary or artistic, except as defined by statute.''

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Patch: Win32, more informative file failure messages
by Neil Mitchell 15 May '09

15 May '09

Hi, Attached is a patch to give more informative failure messages in the Win32 package. Currently we get: $ ghci GHCi, version 6.10.2: http://www.haskell.org/ghc/ :? for help Prelude> :m System.Directory Prelude System.Directory> removeFile "wibble" *** Exception: DeleteFile: does not exist (The system cannot find the file speci fied.) Prelude System.Directory> removeFile "c:/ghc/ghc-6.10.2/bin/ghci.exe" *** Exception: DeleteFile: permission denied (Access is denied.) Now, we should get: *** Exception: DeleteFile "wibble": does not exist (The system cannot find the file specified.) *** Exception: DeleteFile "c:/ghc/ghc-6.10.2/bin/ghci.exe": permission denied (Access is denied.) I have compiled the patches, but not tested them. When I do, I get errors about linking, which I'm pretty sure have nothing to do with my patch. : C:\Program Files\Haskell\Win32-2.2.0.0\ghc-6.10.2\HSWin32-2.2.0.0.o: unknown s ymbol `___stginit_basezm3zi0zi3zi1_Foreign_' I suspect it's because Win32 is built and distributed with GHC. Also, I noticed that: $ cabal install Win32 --global --reinstall System\Win32\SimpleMAPI.hsc:16:63: Module `Control.Exception' does not export `onException' cabal: Error: some packages failed to install: Win32-2.2.0.0 failed during the building phase. The exception was: exit: ExitFailure 1 I'm now left with a dead version of GHC - for future reference, is there a sequence of steps that would have worked to install Win32 and start using the new one? Thanks Neil

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Platform policy question: API compatability in minor releases
by Duncan Coutts 15 May '09

15 May '09

Hello everyone, We (the platform release team) have a policy question about the Haskell Platform. We're asking here because we think the libraries list is the right authority to decide. The Haskell Platform concept calls for major and minor releases. * The point of major releases is to update the set of common packages we all use. That is, to specify which packages and which versions (corresponding to APIs). The target is to have major releases every 6 months. * The point of minor releases is to support a major release across a range of operating systems over time and respond to bugs that are discovered in a library or tool subsequent to their release. The target is to have 2-3 minor releases after major releases at intervals on the order of 4-6 weeks. The question is this: Should we allow compatible API additions to a library in a minor release of the platform? The choice is between allowing only bug fixes in minor releases, or also allowing new features that add APIs but do not change any existing APIs. It is clear that incompatible API changes must not be allowed in minor releases. On the other hand, bug fixes that do not change the API at all are ok. Let me put some arguments in each case: Allow compatible API additions If the change is compatible then it does not break any existing programs, so it should be allowed. Any program that works with a platform particular release will continue to work with subsequent minor versions. This is standard backwards compatibility policy. Getting minor feature improvements is sufficiently important that it is too long to wait 6 months for the next major release of the platform. Allow only bug fixes, no API additions Forwards compatibility is important too. A developer should be able to make a package and test it with platform version X.Y.2 and it should still work for a user with version X.Y.1. That way we do not force upgrades on users all the time. Users should only have to upgrade to a later minor release if earlier versions didn't build/install/work on their OS, or if they hit some particular bug which is fixed in a later minor release. There is no need for API changes in minor releases. Maintainers can make a release with just the bug fixes to go into a minor platform release and then make additional releases with new features on Hackage. Users who want the new features can get the new package version from Hackage. API additions in minor releases works against the distinction between major and minor releases. I hope that's not too biased a summary (I'll post my own opinion separately). If there is anything that I should clarify then please ask. So please post your thoughts and arguments. I hope we can come to a conclusion within a few days. This is a timely issue because we aim to make a minor release on the 1st of June and we want to finalise the list of package versions two weeks prior, by the 18th of May. http://trac.haskell.org/haskell-platform/wiki/ReleaseProcess Duncan

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Re: [Haskell-cafe] Removing mtl from the Haskell Platform
by Wolfgang Jeltsch 14 May '09

14 May '09

Am Mittwoch, 13. Mai 2009 01:03 schrieb roconnor(a)theorem.ca: > I wanted to pass this idea around the cafe to get some thoughts before > submitting a trac on this topic. > > I'd like to see the mtl removed from the Haskell Platform. > > The mtl was a tremendous step forward when it was developed. However, we > have learned a few things about monad transformers since the development > of the mtl, and it is time that we moved forward. > > There are at least 3 significant problem with the mtl. > > 1) `pass' should not be a member functions of the MonadWriter class. It > is my understanding that there is no `MonadWriter w m => MonadWriter w > (ContT s m)' instance because the `pass' function cannot be implemented. > I'm also highly suspicious of some other methods too (I'm looking at you > `local'). > > 2) The `StateT s (Cont r a)' instance of callCC is wrong. The paper on > modular monad transformers > <http://www.cs.nott.ac.uk/~mjj/pubs/mmt/mmt.pdf> describes why this is > wrong. > > 3) I am told by many people that the order of the state and value pair in > `State' is backwards. Actually, I'm not entirely sure what the issue is > here, but I trust the people who say this. 4) The identifiers State and StateT are flawed. Something of value State s a doesn’t denote a state but a state transformer or however you want to name it. Best wishes, Wolfgang

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HsSyck bug?
by Paolo Losi 14 May '09

14 May '09

Hi all, I'm testing HsSyck on a stock debian 5.0 and debian packaged ghc 6.8.2 and 6.10.2 I'm experiencing a strange/repeatable error with Buff packing and unpacking from the attached script. Is this a known issue? Can anyone shed some light? Thanks Paolo (HsSyck)paolo@eee:~/pkgenv$ ./test_yaml ?a? (the script outputs garbage instead of "foo") Thanks Paolo

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