April 2009 - Haskell-Cafe

Haskell Weekly News: Issue 112 - April 5, 2009
by Brent Yorgey 05 Apr '09

05 Apr '09

--------------------------------------------------------------------------- Haskell Weekly News http://sequence.complete.org/hwn/20090405 Issue 112 - April 05, 2009 --------------------------------------------------------------------------- Welcome to issue 112 of HWN, a newsletter covering developments in the [1]Haskell community. Announcements hgettext-0.1.5 - GetText based internationalization of Haskell programs. Vasyl Pasternak [2]announced a new release of the [3]hgettext package for internationalization of Haskell programs, which now supports distribution and installation of PO files. Buster 0.99.1, a library for application orchestration that is not FRP. Jeff Heard [4]announced the release of [5]Buster, an FRP-like framework for constructing reactive programs with a bus model. Call for Contributions - Haskell Communities and Activities Report, May 2009 edition. Janis Voigtlaender [6]issued a call for contributions to the 16th edition of the [7]Haskell Communities & Activities Report. The submission deadline is 1 May 2009. If you are working on any project that is in some way related to Haskell, please write a short entry and submit it. Even if the project is very small or unfinished or you think it is not important enough -- please reconsider and submit an entry anyway! fad 1.0 -- Forward Automatic Differentiation library. Bjorn Buckwalter [8]announced the initial release of the Haskell [9]fad library, developed by Barak A. Pearlmutter and Jeffrey Mark Siskind. Fad provides Forward Automatic Differentiation (AD) for functions polymorphic over instances of 'Num'. hledger 0.4 released. Simon Michael [10]announced the release of [11]hledger 0.4, a text-mode double-entry accounting tool. It reads a plain text journal file describing your transactions and generates precise activity and balance reports. Changes include the ability to serve reports in a web browser, and many other fixes and improvements. GHC version 6.10.2. Ian Lynagh [12]announced a new patchlevel release of [13]GHC. This release contains a number of bugfixes relative to 6.10.1, including some performance fixes; see the [14]release notes. Beta of Leksah IDE available. Jürgen Nicklisch-Franken [15]announced release 0.4.4 of [16]Leksah, the Haskell IDE written in Haskell. Current features include on the fly error reporting with location of compilation errors, completion , import helper for constructing import statements, module browser with navigation to definition, project management support based on Cabal with a visual editor, "source candy", and more. satchmo: monadic SAT encoding library. Johannes Waldmann [17]announced a preliminary version of [18]satchmo, a monadic library for encoding boolean and integral number constraints to CNF-SAT. It uses [19]minisat as a backend solver. vacuum-cairo: a cairo frontend to vacuum for live Haskell data visualization. Don Stewart [20]announced the release of [21]vacuum-cairo, a Haskell library for interactive rendering and display of values on the GHC heap using Matt Morrow's vacuum library. This library takes vacuum's output, generates dot graph format from it, renders it to SVG with graphviz, and displays the resulting structure using the gtk2hs Cairo vector graphics bindings ... all at the GHCi command line. Watch some [22]screencasts! vacuum: extract graph representations of ghc heap values.. Matt Morrow [23]announced the release of [24]vacuum, a library for extracting graph representations of values from the GHC heap, which may then be further processed and/or translated to Graphviz dot format to be visualized. new release of HTTP, version 4000.0.5. Sigbjorn Finne [25]announced a [26]new version of the HTTP package, which includes a bunch of fixes and cleanups along with some API documentation. type-level programming support library. spoon [27]asked for feedback on a [28]support library for type level programming. cmonad 0.1.1. Lennart Augustsson [29]announced the [30]CMonad package, which allows one to write Haskell code in a C style. Marketing Haskell. Ketil "Simon Peyton-Jones" Malde [31]announced the new [32]official Haskell mascot. Haskell Platform: status update and call for volunteers. Duncan Coutts gave an [33]update on the status of the [34]Haskell Platform. There are no more policy questions to resolve for the first release. It is a matter of getting things done. The first platform release will contain ghc-6.10.2, the "extra libs", haddock, happy and alex, and the cabal command line tool and it's dependencies. We are calling for volunteers for an action group. We need volunteers to take charge of various platforms and to manage the overall release. See Duncan's email for a list of what is needed, and volunteer! Blog noise [35]Haskell news from the [36]blogosphere. * Jeff Heard: [37]Major updates to Buster. * Bjorn Buckwalter: [38]ANNOUNCE: fad 1.0---Forward Automatic Differentiation for Haskell. * Roman Cheplyaka: [39]Hpysics + GrapeFruit (and hackathon). * Joachim Breitner: [40]Bejeweled AI in Haskell. * >>> iampalmmute: [41]Vacuum + Ubigraph. Visualizing Haskell values in 3D. * Jeff Heard: [42]ANN: Buster, the not quite entirely unlike FRP library.. * Edward Kmett: [43]Reflecting On Incremental Folds. * beelsebob: [44]How you should(n't) use Monad. * Sean Leather: [45]Incremental attributes. * Jeff Heard: [46]Almost, but not quite entirely unlike FRP.. * >>> Gregory Collins: [47]Building a website with Haskell, part 2. * >>> Rubin Mcgowan: [48]Irradiation Tracing in Haskell. * Conal Elliott: [49]Notions of purity in Haskell. * mightybyte: [50]Finished HAppS Application. * Sean Leather: [51]Experiments with EMGM: Emacs org files. * Yi: [52]Haddock is back. * >>> Lab 49: [53]Does Haskell Support Subtyping? It Depends.. * >>> Tim Lopez: [54]Haskell Performance: Lowercase. * >>> Gregory Collins: [55]Building a website with Haskell, part 1. * happstack.com: [56]Happstack-powered Website launched by Gregory David Collins. * >>> LispCast: [57]Writing map in Haskell. * >>> hellfeuer: [58]Laziness and Dynamic Programming. * >>> Leon Smith: [59]Lloyd Allison's Corecursive Queues. Quotes of the Week * mstr: haskell is like f'gg'fggf'fg'g'fg'foldliftM2 f g ''f' :) * simonmar: Wondering how popular Haskell needs to become for intel to optimize their processors for my runtime, rather than the other way around * quicksilver: [about uninstalling packages installed with cabal-install] packages are for life, not just for christmas. * Ethereal: If this conversation had been had in #python #ruby or #php it would have lots of angry people shouting about how it doesn't matter or isn't true or isn't important and what's the point, and no, you guys are like ahhh but no, your preconceived notions of dimensional space are so passe. * Duqicnk: a monad is like a train that runs backwards in time, which is made of tiny chocolate robots * jfredett: I do all of my version numbers in Roman Numerals... * Cale: But in another sense, functional programmers are applied logicians who spend all their time proving trivial theorems in interesting ways in an inconsistent intuitionist logic. About the Haskell Weekly News New editions are posted to [60]the Haskell mailing list as well as to [61]the Haskell Sequence and [62]Planet Haskell. [63]RSS is also available, and headlines appear on [64]haskell.org. To help create new editions of this newsletter, please see the information on [65]how to contribute. Send stories to byorgey at cis dot upenn dot edu. The darcs repository is available at darcs get [66]http://code.haskell.org/~byorgey/code/hwn/ . References 1. http://haskell.org/ 2. http://article.gmane.org/gmane.comp.lang.haskell.cafe/56301 3. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hgettext 4. http://article.gmane.org/gmane.comp.lang.haskell.cafe/56209 5. http://vis.renci.org/jeff/buster 6. http://article.gmane.org/gmane.comp.lang.haskell.cafe/56148 7. http://www.haskell.org/communities/ 8. http://article.gmane.org/gmane.comp.lang.haskell.cafe/56268 9. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/fad 10. http://article.gmane.org/gmane.comp.lang.haskell.general/17054 11. http://hledger.org/ 12. http://article.gmane.org/gmane.comp.lang.haskell.general/17041 13. http://www.haskell.org/ghc/ 14. http://haskell.org/ghc/docs/6.10.2/html/users_guide/release-6-10-2.html 15. http://article.gmane.org/gmane.comp.lang.haskell.cafe/56116 16. http://www.leksah.org/ 17. http://article.gmane.org/gmane.comp.lang.haskell.cafe/56107 18. http://dfa.imn.htwk-leipzig.de/satchmo/ 19. http://minisat.se/ 20. http://article.gmane.org/gmane.comp.lang.haskell.cafe/56063 21. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/vacuum-cairo 22. http://www.youtube.com/watch?v=oujaqo9GAmA 23. http://article.gmane.org/gmane.comp.lang.haskell.cafe/56062 24. http://moonpatio.com/vacuum/ 25. http://article.gmane.org/gmane.comp.lang.haskell.cafe/56058 26. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/HTTP 27. http://article.gmane.org/gmane.comp.lang.haskell.cafe/55983 28. http://www.killersmurf.com/projects/typelib 29. http://article.gmane.org/gmane.comp.lang.haskell.cafe/55936 30. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/cmonad 31. http://article.gmane.org/gmane.comp.lang.haskell.general/17021 32. http://www.haskell.org/pipermail/haskell/attachments/20090401/9fb8fa05/hask… 33. http://article.gmane.org/gmane.comp.lang.haskell.general/17020 34. http://www.haskell.org/haskellwiki/Haskell_Platform 35. http://planet.haskell.org/ 36. http://haskell.org/haskellwiki/Blog_articles 37. http://vis.renci.org/jeff/2009/04/03/major-updates-to-buster/ 38. http://flygdynamikern.blogspot.com/2009/04/announce-fad-10-forward-automati… 39. http://physics-dph.blogspot.com/2009/04/hpysics-grapefruit-and-hackathon.ht… 40. https://www.joachim-breitner.de/blog/archives/324-Bejeweled-AI-in-Haskell.h… 41. http://www.youtube.com/watch?v=3mMH1cHWB6c 42. http://vis.renci.org/jeff/2009/04/01/ann-buster-the-not-quite-entirely-unli… 43. http://comonad.com/reader/2009/incremental-folds/ 44. http://noordering.wordpress.com/2009/03/31/how-you-shouldnt-use-monad/ 45. http://feedproxy.google.com/~r/splonderzoek/~3/4B0bHoeTCeQ/incremental-attr… 46. http://vis.renci.org/jeff/2009/03/31/almost-but-not-quite-entirely-like-frp/ 47. http://gregorycollins.net/posts/2009/03/30/building-a-website-part-2 48. http://rubinmcgowaneh.blogspot.com/2009/03/irradiation-tracing-in-haskell.h… 49. http://conal.net/blog/posts/notions-of-purity-in-haskell/ 50. http://softwaresimply.blogspot.com/2008/02/finished-happs-application.html 51. http://feedproxy.google.com/~r/splonderzoek/~3/6bxI33NIRMc/experiments-with… 52. http://yi-editor.blogspot.com/2009/03/haddock-is-back.html 53. http://blog.lab49.com/archives/2954 54. http://www.brool.com/index.php/haskell-performance-lowercase 55. http://gregorycollins.net/posts/2009/03/28/building-a-website-part-1 56. http://blog.happstack.com/2009/03/28/happstack-powered-website-launched-by-… 57. http://www.lispcast.com/haskell-map.html 58. http://caffeinatedcode.wordpress.com/2009/03/26/laziness-and-dynamic-progra… 59. http://blog.melding-monads.com/2009/03/09/lloyd-allisons-corecursive-queues/ 60. http://www.haskell.org/mailman/listinfo/haskell 61. http://sequence.complete.org/ 62. http://planet.haskell.org/ 63. http://sequence.complete.org/node/feed 64. http://haskell.org/ 65. http://haskell.org/haskellwiki/HWN 66. http://code.haskell.org/~byorgey/code/hwn/

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Re: [Haskell-cafe] Combining sequences
by michael rice 04 Apr '09

04 Apr '09

Thanks, guys! This one works perfectly. I was monkeying with similar logic but wasn't sure about syntax. Michael --- On Sat, 4/4/09, Andrew Wagner <wagner.andrew(a)gmail.com> wrote: From: Andrew Wagner <wagner.andrew(a)gmail.com> Subject: Re: [Haskell-cafe] Combining sequences To: "michael rice" <nowgate(a)yahoo.com> Cc: haskell-cafe(a)haskell.org Date: Saturday, April 4, 2009, 8:56 PM Here's a pretty straightforward approach: combine [] ys = ys combine xs [] = xs combine (x:xs) (y:ys) | x <= y = x : combine xs (y:ys) | otherwise = y : combine (x:xs) ys On Sat, Apr 4, 2009 at 8:40 PM, michael rice <nowgate(a)yahoo.com> wrote: Is there a simple way to combine two sequences that are in ascending order into a single sequence that's also in ascending order? An example would be the squares [1,4,9,16,25..] combined with the cubes [1,8,27,64,125..] to form [1,1,4,8,9,16,25,27..]. Michael _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe(a)haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

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ANNOUNCE: fad 1.0 -- Forward Automatic Differentiation library
by Bjorn Buckwalter 04 Apr '09

04 Apr '09

I'm pleased to announce the initial release of the Haskell fad library, developed by Barak A. Pearlmutter and Jeffrey Mark Siskind. Fad provides Forward Automatic Differentiation (AD) for functions polymorphic over instances of 'Num'. There have been many Haskell implementations of forward AD, with varying levels of completeness, published in papers and blog posts[1], but alarmingly few of these have made it into hackage -- to date Conal Elliot's vector-spaces[2] package is the only one I am aware of. Fad is an attempt to make as comprehensive and usable a forward AD package as is possible in Haskell. However, correctness is given priority over ease of use, and this is in my opinion the defining quality of fad. Specifically, Fad leverages Haskell's expressive type system to tackle the problem of _perturbation confusion_, brought to light in Pearlmutter and Siskind's 2005 paper "Perturbation Confusion and Referential Transparency"[3]. Fad prevents perturbation confusion by employing type-level "branding" as proposed by myself in a 2007 post to haskell-cafe[4]. To the best of our knowledge all other forward AD implementations in Haskell are susceptible to perturbation confusion. As this library has been in the works for quite some time it is worth noting that it hasn't benefited from Conal's ground-breaking work[5] in the area. Once we wrap our heads around his beautiful constructs perhaps we'll be able to borrow some tricks from him. As mentioned already, fad was developed primarily by Barak A. Pearlmutter and Jeffrey Mark Siskind. My own contribution has been providing Haskell infrastructure support and wrapping up loose ends in order to get the library into a releasable state. Many thanks to Barak and Jeffrey for permitting me to release fad under the BSD license. Fad resides on GitHub[6] and hackage[7] and is only a "cabal install fad" away! What follows is Fad's README, refer to the haddocks for detailed documentation. Thanks, Bjorn Buckwalter [1] http://www.haskell.org/haskellwiki/Functional_differentiation [2] http://www.haskell.org/haskellwiki/Vector-space [3]: http://www.bcl.hamilton.ie/~qobi/nesting/papers/ifl2005.pdf [4]: http://thread.gmane.org/gmane.comp.lang.haskell.cafe/22308/ [5]: http://conal.net/papers/beautiful-differentiation/ [6] http://github.com/bjornbm/fad/ [7] http://hackage.haskell.org/cgi-bin/hackage-scripts/package/fad ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Copyright : 2008-2009, Barak A. Pearlmutter and Jeffrey Mark Siskind License : BSD3 Maintainer : bjorn.buckwalter(a)gmail.com Stability : experimental Portability: GHC only? Forward Automatic Differentiation via overloading to perform nonstandard interpretation that replaces original numeric type with corresponding generalized dual number type. Each invocation of the differentiation function introduces a distinct perturbation, which requires a distinct dual number type. In order to prevent these from being confused, tagging, called branding in the Haskell community, is used. This seems to prevent perturbation confusion, although it would be nice to have an actual proof of this. The technique does require adding invocations of lift at appropriate places when nesting is present. For more information on perturbation confusion and the solution employed in this library see: <http://www.bcl.hamilton.ie/~barak/papers/ifl2005.pdf> <http://thread.gmane.org/gmane.comp.lang.haskell.cafe/22308/> Installation ============ To install: cabal install Or: runhaskell Setup.lhs configure runhaskell Setup.lhs build runhaskell Setup.lhs install Examples ======== Define an example function 'f': > import Numeric.FAD > f x = 6 - 5 * x + x ^ 2 -- Our example function Basic usage of the differentiation operator: > y = f 2 -- f(2) = 0 > y' = diff f 2 -- First derivative f'(2) = -1 > y'' = diff (diff f) 2 -- Second derivative f''(2) = 2 List of derivatives: > ys = take 3 $ diffs f 2 -- [0, -1, 2] Example optimization method; find a zero using Newton's method: > y_newton1 = zeroNewton f 0 -- converges to first zero at 2.0. > y_newton2 = zeroNewton f 10 -- converges to second zero at 3.0. Credits ======= Authors: Copyright 2008, Barak A. Pearlmutter <barak(a)cs.nuim.ie> & Jeffrey Mark Siskind <qobi(a)purdue.edu> Work started as stripped-down version of higher-order tower code published by Jerzy Karczmarczuk <jerzy.karczmarczuk(a)info.unicaen.fr> which used a non-standard standard prelude. Initial perturbation-confusing code is a modified version of <http://cdsmith.wordpress.com/2007/11/29/some-playing-with-derivatives/> Tag trick, called "branding" in the Haskell community, from Bjorn Buckwalter <bjorn.buckwalter(a)gmail.com> <http://thread.gmane.org/gmane.comp.lang.haskell.cafe/22308/> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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Announcement: Beta of Leksah IDE available
by Jürgen Nicklisch-Franken 04 Apr '09

04 Apr '09

I'm proud to announce release 0.4.4 of Leksah, the Haskell IDE written in Haskell. Leksahs current features include: * On the fly error reporting with location of compilation errors * Completion * Import helper for constructing the import statements * Module browser with navigation to definition * Search for identifiers with information about types and comments * Project management support based on Cabal with a visual editor * Haskell customised editor with "source candy" * Configuration with session support, keymaps and flexible panes For further information: leksah.org Please don't compare what we have reached to IDE's like VisualStudio, Eclipse or NetBeans. I started Leksah June 1997 and work on it in my spare time for fun. I started the project for various reasons. One was to contribute to make Haskell successful in industry, because I suffer from the use of inappropriate programming languages like C, C++, C# or Java in my daily job. Another was to contribute to open source, which I'm using privately almost exclusively. The first alpha version of Leksah was published February 2008. Since the beginning of this year Hamish Mackenzie joined the project and merged his Funa project with Leksah, which gave a real boost. I thank the people who have encouraged and helped me with their comments, enthusiasm and support. I learned as well that the IDE issue is a controversial theme in the community. I learned that "IDEs are big evil nasty things", that "if you need an IDE, something is wrong with your language", that it is scientifically proved, that "real cool hackers will always use Emacs or vi". Most stupid I found the recurring comment: "Every few years there is someone who starts a Haskell IDE project and then gives up after a few years.". That will be true for Leksah as well, if it will not be accepted and supported by the community. The current state of Leksah is a proof of concept, that an IDE for Haskell is not a difficult thing to do if the community supports it and that it will in my view be of great help and will contribute tremendously to spread Haskell. So I please the members of the community to pause for a moment and try out Leksah with a benevolent attitude. Jürgen Nicklisch-Franken

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.editrc
by brad clawsie 04 Apr '09

04 Apr '09

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 does anyone have a .editrc they can provide that allows ghci to be used on freebsd? i'm not looking for anything fancy, just backspace not being broken etc thanks brad -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.10 (Darwin) iEYEARECAAYFAknVGdQACgkQxRg3RkRK91NZ4gCgm8Oktcs3sCYl6YoY6X4igZAR IDIAn2cpF7QnI4zz4LFN1cVlzG7qSHHk =CJXp -----END PGP SIGNATURE-----

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First time I've gotten gtk2hs to install from ports on Mac OS X from scratch
by Jeff Heard 04 Apr '09

04 Apr '09

The instructions in the leksah manuals seem to work for doing a straight-up ports install of gtk2hs. I've never managed to get it to install without compiling manually, but this worked $ sudo port install gtk2 cairo librsvg libglade2 gtksourceview2 gtkglext gtk-chtheme gtk2-clearlooks $ sudo port -k install ghc gtk2hs hs-cabal Unfortunately leksah itself won't link...

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Leksah+Gtk2Hs link error on Mac OS X Leopard
by Jeff Heard 04 Apr '09

04 Apr '09

I tried installing leskah on OS X using the x11 version of gtk2hs (because I use gtkglext a lot in my work, and need it, therefore the quartz build won't work for me) I get these errors. Is this leksah specific or is this a more general problem with gtk2hs? Linking dist/build/leksah/leksah ... ld warning: atom sorting error for _ghczm6zi10zi1_LibFFI_Czuffizutype_closure_tbl and _ghczm6zi10zi1_LibFFI_Czuffizucif_closure_tbl in /opt/local/lib/ghc-6.10.1/ghc-6.10.1/libHSghc-6.10.1.a(LibFFI.o) ld warning: atom sorting error for _ghczm6zi10zi1_LibFFI_Czuffizutype_closure_tbl and _ghczm6zi10zi1_LibFFI_Czuffizucif_closure_tbl in /opt/local/lib/ghc-6.10.1/ghc-6.10.1/libHSghc-6.10.1.a(LibFFI.o) $ ~/.cabal/bin/leksah dyld: lazy symbol binding failed: Symbol not found: _cairo_quartz_font_face_create_for_atsu_font_id Referenced from: /opt/local/lib/libpangocairo-1.0.0.dylib Expected in: /opt/local/lib/libcairo.2.dylib dyld: Symbol not found: _cairo_quartz_font_face_create_for_atsu_font_id Referenced from: /opt/local/lib/libpangocairo-1.0.0.dylib Expected in: /opt/local/lib/libcairo.2.dylib Trace/BPT trap

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about Haskell code written to be "too smart"
by Manlio Perillo 04 Apr '09

04 Apr '09

Hi. In these days I'm discussing with some friends, that mainly use Python as programming language, but know well other languages like Scheme, Prolog, C, and so. These friends are very interested in Haskell, but it seems that the main reason why they don't start to seriously learning it, is that when they start reading some code, they feel the "Perl syndrome". That is, code written to be "too smart", and that end up being totally illegible by Haskell novice. I too have this feeling, from time to time. Since someone is starting to write the Haskell coding style, I really suggest him to take this "problem" into strong consideration. Manlio

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happstack example code wanted
by Johannes Waldmann 04 Apr '09

04 Apr '09

Hi, I'm thinking of using happstack for a simple online registration system. [ Customer gives Name and Address and registers for certain workshops. Then the app server should just produce a bill. (Payment is handled through a different channel.) The "store owner" needs to get some overview of registrations. ] According to happs(tack) marketing department, this should be an easy exercise? Any code that I could use as a starting point? ( Or, if you do the coding, I can link to you from the workshop site. But I don't have a serious budget :-) Thanks - J.W.

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ANN: logfloat 0.12.0.1
by wren ng thornton 04 Apr '09

04 Apr '09

-------------------------------------------- -- logfloat 0.12.0.1 -------------------------------------------- This package provides a type for storing numbers in the log-domain, primarily useful for preventing underflow when multiplying many probabilities as in HMMs and other probabilistic models. The package also provides modules for dealing with floating numbers correctly. -------------------------------------------- -- Now using FFI -------------------------------------------- We now use the FFI to gain access to C's accurate log1p (and expm1) functions. This greatly increases the range of resolution, especially for very small LogFloat values. These are currently exposed from Data.Number.LogFloat, though they may move to a different module in future versions. On GHC 6.10 the use of -fvia-C had to be disabled because it conflicts with the FFI (version 0.12.0.0 still used it, which is fine on GHC 6.8). I'm still investigating the use of -fasm and getting proper benchmarking numbers. Contact me if you notice significant performance degradation. Using the FFI complicates the build process for Hugs; details are noted in the INSTALL file. It may also complicate building on Windows (due to ccall vs stdcall), though I'm not familiar with Windows FFI and don't have a machine to test on. The calling convention is "unsafe" in order to avoid overhead. However, in the past this has been noted to cause issues with multithreaded applications since it locks all RTS threads instead of just the calling thread. If you're using logfloat in a multithreaded application and notice a slowdown, or if you're more familiar with these details than I, tell me so I can fix things. If you have any difficulties with the FFI, let me know. As an interim solution the FFI can be disabled by turning off the useFFI Cabal flag during configure, which will compile the package to use the naive log1p implementation from earlier versions. -------------------------------------------- -- Other changes since 0.11.0 -------------------------------------------- * (0.11.1) Felipe Lessa added an instance for IArray UArray LogFloat. On GHC we use newtype deriving; On Hugs we fall back to unsafeCoerce to distribute the newtype over IArray UArray Double. * (0.11.2 Darcs) Moved the log/exp fusion rules from Data.Number.LogFloat into Data.Number.Transfinite where our log function is defined. * Added a Storable LogFloat instance for GHC. No implementation is available yet for Hugs. * Removed orphaned toRational/fromRational fusion rules, which were obviated by the introduction of the Data.Number.RealToFrac module in 0.11.0. * Changed the Real LogFloat instance to throw errors when trying to convert transfinite values into Rational. -------------------------------------------- -- Compatibility / Portability -------------------------------------------- The package is compatible with Hugs (September 2006) and GHC (6.8, 6.10). For anyone still using GHC 6.6, the code may still work if you replace LANGUAGE pragma by equivalent OPTIONS_GHC pragma. The package is not compatible with nhc98 and Yhc because Data.Number.RealToFrac uses MPTCs. The other modules should be compatible. -------------------------------------------- -- Links -------------------------------------------- Homepage: http://code.haskell.org/~wren/ Hackage: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/logfloat Darcs: http://code.haskell.org/~wren/logfloat/ Haddock (Darcs version): http://code.haskell.org/~wren/logfloat/dist/doc/html/logfloat/ -- Live well, ~wren

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