October 2009 - Haskell-Cafe

How do I uninstall GHC on a Mac running Snow Leopard?
by R J 24 Oct '09

24 Oct '09

What's the cleanest way to fully uninstall GHC on a Mac running Snow Leopard? Running Library/Frameworks/GHC.framework/Tools/Uninstaller from an account with admin privileges produced the following, surprising error message: > GHC.framework installer must be run with admin privileges> Prefix command by 'sudo'> logout > [Process completed] Thanks as always. _________________________________________________________________ Windows 7: Simplify your PC. Learn more. http://www.microsoft.com/Windows/windows-7/default.aspx?ocid=PID24727::T:WL…

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What is the current state of affairs with supercompilation?
by Eugene Kirpichov 24 Oct '09

24 Oct '09

Hi. I became intrigued with supercompilation; what is the current state of affairs with it? I know that there exist experimental supercompilers for Java and REFAL. I know of the existence of jhc and its follower lhc, although I don't know quite well what they can and what they can't. I know that ghc is probably going to have a supercompiler inside. I, again, don't know how broads the plans are. I'm mainly interested in the following: - What supercompilers do exist, except for the ones mentioned above? - What academic organizations do research in the area? - What papers should be read by someone eager to learn about supercompilation and maybe to make research contributions? - What are some solved problems and some open problems in supercompilation? -- Eugene Kirpichov Web IR developer, market.yandex.ru

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Haskell Weekly News: Issue 136 - October 24, 2009
by jfredett＠gmail.com 24 Oct '09

24 Oct '09

--------------------------------------------------------------------------- Haskell Weekly News http://sequence.complete.org/hwn/20091024 Issue 136 - October 24, 2009 --------------------------------------------------------------------------- Welcome to issue 136 of HWN, a newsletter covering developments in the [1]Haskell community. Short one this week, I have GREs today, so I've spent more time aggregating GRE knowledge rather than Haskell news. Till next week, Haskellers, The Haskell Weekly News! Announcements PastePipe -- a CLI for hpaste instances. Rogan Creswick [2]announced a new version of PastePipe, a library which reads from stdin and posts it to an hpaste instance (defaulting to hpaste.org) haskell-src-exts-1.2.0. Niklas Broberg [3]announced a major release of haskell-src-exts. Several breaking changes, a few (ideally) backwards compatable changes. See the post for all the details. mecha-0.0.0. Tom Hawkins [4]announced a very cool new DSL in Haskell for Constructive Solid Modelling. GPipe 1.02 and Vec-Transform 1.0.1. Tobias Bexelius [5]announced new versions of these packages, only a few API changes Data.Stream 0.4. Wouter Swierstra [6]announced a very delicate change to Data.Stream involving irrefutable patterns. Specifically added them in functions which produce new streams from old. strptime bindings. Eugene Kirpichov [7]announced bindings to strptime. cereal-0.2. Trevor Elliott [8]announced a new version of the cereal library, a variation on the `binary` package which provides strict parsing. quickcheck-poly. Ki Yung Ahn [9]announced a package for testing polymorphic functions automatically. 2nd CFP: JSC Special Issue on Automated Verification and Specification of Web Systems. demis [10]announced a special issue of the Journal of Symbolic Computation. The issue contains articles relating to Automated Specification and Verification of Web Systems. qtHaskell-1.1.3. David Harley [11]announced a new version of qtHaskell. Discussion Is there in Haskell the eval function? Waldemar Biernacki [12]asked about an `eval` function for Haskell. What's this pattern called? Martijn van Steenbergen [13]asked about a common pattern for an simple EDSL AST-like type. Problems with Haskell. Philippos Apolinarius [14]forwarded his response to a [15]Clean programmer who planned a move to Haskell upon fears of Clean being around for the long term. A very nice read. Statically checked binomail heaps? Maciej Kotowicz [16]talked about his implementation of Statically Checked Binomial Heaps in Haskell Blog noise [17]Haskell news from the [18]blogosphere. Blog posts from people new to the Haskell community are marked with >>>, be sure to welcome them! * Mikael Vejdemo Johansson (Syzygy-): [19][MATH198] Lecture 5 is up. * JP Moresmau: [20]Releasing my code on the unsuspecting public (EclipseFP). * Neil Brown: [21]Benchmarking STM with Criterion. * Galois, Inc: . * Brent Yorgey: [22]Typeclassopedia in Japanese!. * Neil Brown: [23]An early look at ThreadScope, a tool for profiling concurrent and parallel Haskell programs. * FP-Syd: [24]Sydney FP Group: FP-Syd #19.. * Michael Snoyman: [25]Monadic pairs and Kleisli arrows. * Martijn van Steenbergen: [26]Transforming polymorphic values. * Manuel M T Chakravarty: [27]Multicore Haskell Now!. * Don Stewart (dons): [28]Multicore Haskell Now! ACM Reflections | Projections 2009. * Dan Piponi (sigfpe): [29]What Category do Haskell Types and Functions Live In?. * Manuel M T Chakravarty: [30]Don Stewart's talk on Domain Specific Languages and Haskell. Quotes of the Week * Veinor: I program in austere haskell. I name all my variables a, a', a'', a''', etc * ddarius: releases network version 127.0.0.1 * Berengal: 'Bobby Boolean felt horrible. What did he ever do to the other values? He was just a simple bit, a simple answer to a simple question! Suddenly he felt his insides churn; he felt an exception coming on! Oh no! What should he do, now that he was outside of IO?' * Berengal: '"Go away! You're not like us!" the other values yelled. "You're impure! Impure! Impure! Impure!" they started chanting.' * dpratt71: <dpratt71> so I read somewhere that the unofficial motto of Haskell was "avoid success at all costs"... <Baughn> dpratt71: Yeah. We failed. * Warrigal: Note to self: don't do maximum [1..]. * mauke: the first and foremost task of a haskell compiler is to break haskell programs * ksf: ...premature generalisation is the root of all procrastination. * jimi_hendrix: that took longer than it should have, but it feels so pure * ddarius: Unfortunately, the logic programming community has this unhealthy death grip on Prolog. About the Haskell Weekly News New editions are posted to [31]the Haskell mailing list as well as to [32]the Haskell Sequence and [33]Planet Haskell. [34]RSS is also available, and headlines appear on [35]haskell.org. To help create new editions of this newsletter, please see the information on [36]how to contribute. Send stories to jfredett . at . gmail . dot . com. The darcs repository is available at darcs get [37]http://patch-tag.com/r/jfredett/HWN2/pullrepo HWN2 . References Visible links 1. http://haskell.org/ 2. http://article.gmane.org/gmane.comp.lang.haskell.cafe/65222 3. http://article.gmane.org/gmane.comp.lang.haskell.cafe/65219 4. http://article.gmane.org/gmane.comp.lang.haskell.cafe/65134 5. http://article.gmane.org/gmane.comp.lang.haskell.cafe/65119 6. http://article.gmane.org/gmane.comp.lang.haskell.cafe/65116 7. http://article.gmane.org/gmane.comp.lang.haskell.cafe/65061 8. http://article.gmane.org/gmane.comp.lang.haskell.cafe/65043 9. http://article.gmane.org/gmane.comp.lang.haskell.general/17586 10. http://article.gmane.org/gmane.comp.lang.haskell.general/17585 11. http://article.gmane.org/gmane.comp.lang.haskell.general/17583 12. http://thread.gmane.org/gmane.comp.lang.haskell.cafe/65153 13. http://thread.gmane.org/gmane.comp.lang.haskell.cafe/65148 14. http://thread.gmane.org/gmane.comp.lang.haskell.cafe/65014 15. http://clean.cs.ru.nl/ 16. http://thread.gmane.org/gmane.comp.lang.haskell.cafe/64998 17. http://planet.haskell.org/ 18. http://haskell.org/haskellwiki/Blog_articles 19. http://blog.mikael.johanssons.org/archive/2009/10/math198-lecture-5-is-up/ 20. http://jpmoresmau.blogspot.com/2009/10/releasing-my-code-on-unsuspecting.ht… 21. http://chplib.wordpress.com/2009/10/21/benchmarking-stm-with-criterion/ 22. http://byorgey.wordpress.com/2009/10/20/typeclassopedia-in-japanese/ 23. http://chplib.wordpress.com/2009/10/19/an-early-look-at-threadscope/ 24. http://www.mega-nerd.com/erikd/Blog/FP-Syd/fp-syd-19.html 25. http://blog.snoyman.com/2009/10/19/monadic-pairs-and-kleisli-arrows/ 26. http://martijn.van.steenbergen.nl/journal/2009/10/18/transforming-polymorph… 27. http://justtesting.org/post/216085196 28. http://donsbot.wordpress.com/2009/10/17/multicore-haskell-now-acm-reflectio… 29. http://blog.sigfpe.com/2009/10/what-category-do-haskell-types-and.html 30. http://justtesting.org/post/215438784 31. http://www.haskell.org/mailman/listinfo/haskell 32. http://sequence.complete.org/ 33. http://planet.haskell.org/ 34. http://sequence.complete.org/node/feed 35. http://haskell.org/ 36. http://haskell.org/haskellwiki/HWN 37. http://patch-tag.com/r/jfredett/HWN2/pullrepo%20HWN2 Hidden links: 38. http://www.galois.com/blog/2009/10/20/crenshaw-simplex/

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What does :*: mean again?
by Günther Schmidt 23 Oct '09

23 Oct '09

Günther

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ANN: haskell-src-exts-1.2.0
by Niklas Broberg 23 Oct '09

23 Oct '09

Fellow Haskelleers, I'm pleased to announce the release of haskell-src-exts-1.2.0! * On hackage: http://hackage.haskell.org/package/haskell-src-exts * Via cabal: cabal install haskell-src-exts * Darcs repo: http://code.haskell.org/haskell-src-exts Version 1.2.0 is a new major release, following the PVP, as it contains a few backwards-incompatible changes, as well as some major changes that are supposedly backwards-compatible in theory, but as much of it is new and untested in practice there may be some regressions (bugs). The main new thing in 1.2.0 is the integration of the Annotated machinery into the package proper, for instance all parsing is now handled by the fully location-aware parser. haskell-src-exts-1.2.0: ==================== * Language.Haskell.Exts.Annotated.Simplify provides translation from an annotated AST to the old simple AST. * Behind-the-scenes integration of the new exact parser and lexer to do all parsing (using the above mentioned simplifier if the old AST version is requested). * All syntactic nodes now derive Eq, Ord and Show. * Pretty instance for SrcSpan. * Top-level expressions are now treated as implicit TH splice declarations (as per GHC HEAD). Note that this incurs a non-backwards-compatible change to the AST. * Empty data declarations may now have explicit kind annotations. * AST (and Pretty/Exact) support for kind variables (not yet parser support). * Error messages now extensively use prettyPrint instead of show for AST elements and locations, leading to way neater messages. * Bug fix to not crash ungracefully when encountering type equality predicates in proper types. * Liberalise line comments (as per GHC) to allow a line comment on the last line of a source file. Please help me test and report! Grab a darcs version, put your source files in the Test/examples dir, and go cabal test (in the top dir). Any failing cases not due to CPP or literate source files (for the exact-printer), please report to the trac: http://trac.haskell.org/haskell-src-exts Cheers, /Niklas

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Announcing: PastePipe -- a CLI for hpaste instances
by Rogan Creswick 23 Oct '09

23 Oct '09

I'm happy to announce PastePipe (v1.3)! PastePipe reads from stdin and publishes whatever it reads to the hpaste instance of your choice (defaulting to hpaste.org) This makes it trivial to..... * post a file to hpaste.org: `cat <file> | pastepipe' * turn a terminal into a pastebin window: 'pastepipe' (ctrl-d to close & send) * upload error output as a paste: 'faultyProgram | pastepipe -t "faultyProgram error output" -l bash' * paste to a local hpaste instance: 'pastepipe --uri http://my.local.hpaste/fastcgi/hpaste.fgci/' * add a title, select different languages, specify a user name, etc... see pastepipe --help for details. PastePipe will output the resulting url for your new paste to stdout, so you can script it, or just copy / paste that as you need. Availability: ------------------------------------------------------------------------------------------------------- It is available on Hackage (so you can 'cabal install PastePipe'): http://hackage.haskell.org/package/PastePipe The project for pastepipe is hosted at Google Code, with the source in mercurial: Homepage (issue tracker, etc): http://code.google.com/p/pastepipe/ Mercurial repo: hg clone https://pastepipe.googlecode.com/hg/ pastepipe --------------------------------------------------------------------------------------------------------------- Please let me know of any bugs / feature requests / etc. (or just post them to the issue tracker.) Thanks! Rogan

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Re: \Statically checked binomail heaps?
by Okasaki, C. DR EECS 23 Oct '09

23 Oct '09

Maciej Kotowicz asked about implementing binomial heaps using types to enforce the shape invariants. I dug up an old email from 1998 talking about how to do this with nested types, and posted it to my blog: http://okasaki.blogspot.com/2009/10/binomial-queues-as-nested-type.html -- Chris

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Help me improve design of my project.
by Andy Stewart 23 Oct '09

23 Oct '09

Hi all, I develop some Haskell IDE, below is screenshots: http://farm4.static.flickr.com/3483/3947340553_933df88a22_o.png http://farm3.static.flickr.com/2628/3952175905_9295a7421a_o.png http://farm3.static.flickr.com/2544/3957610799_70fab5eb57_o.png http://farm3.static.flickr.com/2703/4016163374_493e3738c7_o.png Below is source code. You only can compile it with darcs version of gtk2hs. The simple usage is press `F4` open terminal, then press `F7` to type file-path for open. Now is really simple, now i haven't stable time maintain project, so i will opensource my project when i have stable time. Okay, question is, IORefObject module and most module reference each other, so i will got `recursive reference problem` (looks how many .hs-boot in my project). So anyone can help me improve design to split IORefObject and other modules, make them less depend? Thanks, -- Andy

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FW: Free Pizza, C++, and Haskell
by Simon Peyton-Jones 23 Oct '09

23 Oct '09

You may enjoy this interesting blog post by Bartosz Milewski about understanding C++ template metaprogramming by starting with Haskell. http://bartoszmilewski.wordpress.com/2009/10/21/what-does-haskell-have-to-d… Bartosz gave the talk at the Northwest C++ users group; the video for the talk will be linked eventually on the NWCPP website: http://nwcpp.org/ Simon

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Time Typeable Instances
by John Goerzen 23 Oct '09

23 Oct '09

Hugo Gomes wrote: > The Glorious Glasgow Haskell Compilation System, version 6.10.4 > with old-time-1.0.0.2 and time-1.1.2.4 > > This is a standard haskell platform on a windows xp. Cabal install > didn't work complaining about missing instances of typeable for posix > time and other datatypes, yet, after removing the macros (thus, adding > those instances), hdbc and convertible compiled and installed fine. > > Removing the macros might be a bit overkill, probably finetuning them so > that they add only the necessary instances for typeable in ghc > 610 > might be a better solution. I'm going to CC haskell-cafe on this because I am confused. Hugo, can you confirm what version of convertible you have? Back on May 21, I started a thread [1] on haskell-cafe complaining that GHC 6.10.3 included a newer time that included instances of Typeable for NominalDiffTime and UTCTime. This broke my code, which had manually defined instances for these types, as they were needed. Things got complicated, as only time's minor version number got incremented (x.x.x.Y) [2]. Cabal can't test against that version number. I wanted my code to work with old and new versions of GHC. Since testing against the version of time was impossible, I did the next best thing: tested against the version of GHC. #if __GLASGOW_HASKELL__ >= 610 -- instances added in GHC 6.10.3 #else instance Typeable NominalDiffTime where typeOf _ = mkTypeName "NominalDiffTime" instance Typeable UTCTime where typeOf _ = mkTypeName "UTCTime" #endif Also, in the .cabal, there is a build-depends on time>=1.1.2.4. Now, that would break for GHC 6.10.1 and 6.10.2 users, but will work for 6.10.3 and above, or 6.8 and below. Or so I thought. Now I'm getting complaints from people using 6.10.4 saying that there are now missing instances of Typeable with time 1.1.2.4. 1) Did the Typeable instances get dropped again from time? 2) What exactly should I do so this library compiles on GHC 6.8 and 6.10.x? I'm looking at the darcs repo for time and don't see the instances ever getting dropped. [1] http://osdir.com/ml/haskell-cafe@haskell.org/2009-05/msg00982.html [2] http://osdir.com/ml/haskell-cafe@haskell.org/2009-05/msg00985.html .... later addendum .... so it appears that what's happening here is that GHC 6.10.3 extralibs included time 1.1.3, but then haskell-platform standardized on 1.1.2.4. This is pretty annoying -- that haskell-platform would standardize on a version older than what shipped with a GHC release -- but I guess I can work around it by restricting my build-dep to be time < 1.1.3 and re-adding the instances. Does this sound right? > > > On Tue, Oct 13, 2009 at 2:51 AM, John Goerzen <jgoerzen(a)complete.org > <mailto:jgoerzen@complete.org>> wrote: > > Hugo Gomes wrote: > > Hi, > > > > convertible and hdbc packages fail to compile in my standard > instalation > > of the haskell platform. I think this has to do with those "if ghc >= > > 610" macros on the typeable instances for some datatypes. I > removed them > > and now they work fine... > > > > > > > > > What version of GHC and time do you have? > > -- John > >

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