August 2013 - Haskell

ANNOUNCE: ioctl 0.0.1
by Maciej Piechotka 13 Sep '15

13 Sep '15

A package for type-safe I/O control. Currently only ioctl is supported. Currently simply a extract from my tuntap fork TODO: - Return the integer as well as structure (will break the API) - Port for Windows Network.Socket.IOCtl (as soon as I manage to setup some sane environment on this platform) - Wrapping around DeviceIoControl Example (in hsc): data NotRead = NotRead instance NotRead Int where ioctlReq _ = #const FIONREAD notRead s = ioctlsocket' s NotRead Regards

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CFP: Term and Graph rewriting, special issue of MSCS
by Rachid Echahed 13 Feb '14

13 Feb '14

-------------------------------------------------------------------------- First Call for Papers Special Issue of Mathematical Structures in Computer Science (MSCS) on "TERM and GRAPH Rewriting" -------------------------------------------------------------------------- Scope -------------------------------------------------------------------------- Rewriting techniques constitute a foundational theory of computing science. They are being investigated for several structures such as lambda-terms, first-order terms or graphs and have been successfully used in many areas such as programming languages, automated reasoning, program verification, security, etc. This is witnessed by the leading international events ICGT, RTA or TLCA among others. During the last decade, a particular interest has been devoted to the study of the impact of shared structures in term and graph rewriting through the international editions of TERMGRAPH series of workshops. Sharing is indeed ubiquitous in several research areas, for instance: the modelling of first- and higher-order term rewriting by (acyclic or cyclic) graph rewriting, the modelling of biological or chemical abstract machines, the implementation techniques of programming languages. Term and graph rewriting are also used in automated theorem proving and symbolic computation systems working on shared structures... This special issue is devoted to recent developments in all aspects of TERM and GRAPH rewriting. This includes (but is not limited to): term rewriting, graph transformation, proof methods, programming languages, infinitary rewriting, rewrite strategies, semantics, properties of rewriting ... -------------------------------------------------------------------------- Submissions -------------------------------------------------------------------------- Submitted papers must be original and not submitted for publication elsewhere, and will be subject to the standard journal refereeing process of the Mathematical Structures in Computer Science (MSCS) journal. Submissions should be in pdf format following the MSCS instruction for contributors (http://assets.cambridge.org/MSC/MSC_ifc.pdf) and should be submitted electronically via the following easy-chair web site: https://www.easychair.org/conferences/?conf=mscsrewriting2012 -------------------------------------------------------------------------- Important Dates -------------------------------------------------------------------------- January 20, 2012 : Abstract submission February 20, 2012: Paper submission June 15, 2012 : Notification of acceptance -------------------------------------------------------------------------- Guest Editor: -------------------------------------------------------------------------- Rachid Echahed, CNRS LIG Lab., Grenoble, France echahed(a)imag.fr --------------------------------------------------------------------------

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2nd CFP: SCSS 2013
by Temur Kutsia 18 Sep '13

18 Sep '13

[Please post - apologies for multiple copies.] Second Call for Papers SCSS 2013 Symbolic Computation in Software Science 5th International Symposium Castle of Hagenberg, Austria, July 5-6, 2013 Research Institute for Symbolic Computation (RISC) Johannes Kepler University Linz http://www.risc.jku.at/conferences/scss2013/ Scope -------- The purpose of SCSS 2013 is to promote research on theoretical and practical aspects of symbolic computation in software science. The symposium provides a forum for active dialog between researchers from several fields of computer algebra, algebraic geometry, algorithmic combinatorics, computational logic, and software analysis and verification. SCSS 2013 solicits both regular and tool papers on all aspects of symbolic computation and their applications in software science. The topics of the symposium include, but are not limited to the following: - automated reasoning - algorithm (program) synthesis and/or verification - formal methods for the analysis of network security - termination analysis and complexity analysis of algorithms (programs) - extraction of specifications from algorithms (programs) - theorem proving methods and techniques - proof carrying code - generation of inductive assertion for algorithm (programs) - algorithm (program) transformations - formalization and computerization of knowledge (maths, medicine, economy, etc.) - component-based programming - computational origami - query languages (in particular for XML documents) - semantic web and cloud computing Invited Speakers ---------------- Bruno Buchberger (RISC, Johannes Kepler University Linz, Austria) Joel Ouaknine (Oxford University, UK) Program Chair -------------- Laura Kovacs (Vienna University of Technology, Austria and Chalmers University of Technology, Sweden) Program Committee ------------------ María Alpuente (Technical University of Valencia, Spain) Serge Autexier (DFKI, Germany) Nikolaj Bjorner (Microsoft Research) Adel Bouhoula (Higher School of Communications of Tunis, Tunisia) Iliano Cervesato (Carnegie Mellon University — Qatar Campus) Horatiu Cirstea (Loria, France) Jürgen Giesl (RWTH Aachen, Germany) Tetsuo Ida (University of Tsukuba, Japan) Paul Jackson (University of Edinburgh, UK) Tudor Jebelean (RISC, Johannes Kepler University Linz, Austria) Cezary Kaliszyk (University of Innsbruck, Austria) Fairouz Kamareddine (Heriot-Watt University, UK) Temur Kutsia (RISC, Johannes Kepler University Linz, Austria) Stephan Merz (INRIA Lorraine, France) Ali Mili (New Jersey Institute of Technology, USA) Yasuhiko Minamide (University of Tsukuba, Japan) Pierre-Etienne Moreau (INRIA-LORIA Nancy, France) André Platzer (Carnegie Mellon University, USA) Stefan Ratschan (Czech Academy of Sciences) Rachid Rebiha (University of Lugano, Switzerland and IC Unicamp, Brazil) Enric Rodríguez Carbonell (Technical University of Catalonia, Spain) Sorin Stratulat (University of Lorraine, Metz, France) Thomas Sturm (Max Planck Institute for Informatics, Germany) Symposium Chair --------------- Temur Kutsia (RISC, Johannes Kepler University Linz, Austria) Important Dates --------------- April 30, 2013: Abstract submission deadline May 3, 2013: Paper submission deadline June 3, 2013: Notification of acceptance June 17, 2013: Camera-ready copy deadline July 5-6, 2013: SCSS 2013, Castle of Hagenberg, Austria Submission ---------- Submission is via EasyChair: https://www.easychair.org/conferences/?conf=scss2013. Submissions are invited in two categories: regular research papers and tool papers. - Regular research papers must not exceed 12 pages in the EasyChair Class format, with up to 3 additional pages for technical appendices. - Tool papers must not exceed 6 pages in the EasyChair Class format. Publication ---------- The proceedings of SCSS 2013 will be published as a RISC technical report. After the symposium, authors of accepted papers at SCSS 2013 will be invited to submit an extended version of their paper to the special issue of the Journal of Symbolic Computation on SCSS. Submitted papers to the JSC special issue will undergo an additional reviewing.

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PPDP 2013 + LOPSTR 2013 Call for participation
by Ricardo Peña 30 Aug '13

30 Aug '13

(Apologies for multiple copies of this announcement) CALL FOR PARTICIPATION: ========================================================= PPDP 2013 15th International Symposium on Principles and Practice of Declarative Programming Madrid, Spain, September 16-18, 2013 http://users.ugent.be/~tschrijv/PPDP2013/ and LOPSTR 2013 23rd International Symposium on Logic-Based Program Synthesis and Transformation Madrid, Spain, September 18-19, 2013 http://www.utdallas.edu/~gupta/lopstr/ ========================================================= Registration is open now. There is a significant discount if you register for both events. Registration link: http://dalila.sip.ucm.es/ppdp-lopstr-13/?page_id=31 You can access the PPDP 2013 scientific program at: http://users.ugent.be/~tschrijv/PPDP2013/program.pdf You can access the LOPSTR 2013 scientific program at: http://www.utdallas.edu/~gupta/lopstr/lopstr-program.pdf Hope to see you at Madrid

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ANN: Chart library v1.0
by Tim Docker 29 Aug '13

29 Aug '13

I'm pleased to announce version 1.0 of the Chart library - a library for rendering 2D charts in haskell. It supports a variety of plot types, and several different rendering backends. Whilst the library has seen sporadic patches and releases in recent years, development has seen a huge spike over the last 3 months thanks to Jan Bracker's excellent GSOC work. The key changes in this release are: * The rendering backend has been abstracted, and there are rendering implementations for cairo and the diagrams library. The removal of the dependency on cairo should make the chart library more useful to haskell developers on windows and OSX. Jan Bracker has put a huge effort into this change. * The library has switched from using data-accessor to lenses to provide accessors for the plotting data model. Thanks to Ben Gamari for this change. These, along with various other API changes justify a 1.0 version. Details of the library and code examples can be found on the github wiki: https://github.com/timbod7/haskell-chart/wiki The packages and API documentation are on hackage: http://hackage.haskell.org/package/Chart http://hackage.haskell.org/package/Chart-cairo http://hackage.haskell.org/package/Chart-diagrams Tim Docker

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Haskell Weekly News: Issue 278
by Daniel Santa Cruz 29 Aug '13

29 Aug '13

Welcome to issue 278 of the HWN, an issue covering crowd-sourced bits of information about Haskell from around the web. This issue covers the week of August 18 to 24, 2013. Quotes of the Week * johnw: finger trees must be related to palm trees somehow * monochrom: "do, or undo. there is no redo." :) * danharaj: arrows are just strong monads in the 2-category of profunctors. what's the problem? * BMeph: If only they knew the POWER...of the darcs-IDE! * geekosaur: "tekmo and the pipes list" sounds like some kind of postmodernist band Top Reddit Stories * Building an Asteroids Clone in Haskell using Netwire Domain: ocharles.org.uk, Score: 88, Comments: 22 On Reddit: [1] http://goo.gl/HZBtcK Original: [2] http://goo.gl/Gp8TVw * What's new in Cabal 1.18 - sandboxes, REPL, cross-compilation and more! Domain: coldwa.st, Score: 75, Comments: 18 On Reddit: [3] http://goo.gl/8eSChe Original: [4] http://goo.gl/VrHkMY * An Introduction to Cabal sandboxes Domain: coldwa.st, Score: 64, Comments: 33 On Reddit: [5] http://goo.gl/oFGzfK Original: [6] http://goo.gl/ByA6Ru * Reasoning about space leaks with space invariants Domain: apfelmus.nfshost.com, Score: 59, Comments: 48 On Reddit: [7] http://goo.gl/cKlPrM Original: [8] http://goo.gl/E4kIjD * Bound: Making de Bruijn Succ Less on School of Haskell by Edward Kmett Domain: fpcomplete.com, Score: 48, Comments: 14 On Reddit: [9] http://goo.gl/v7tgWO Original: [10] http://goo.gl/glTA3N * PatternSynonyms - ghc trac Domain: ghc.haskell.org, Score: 35, Comments: 14 On Reddit: [11] http://goo.gl/8zuy1T Original: [12] http://goo.gl/5Bw6FN * Revisiting Matrix Multiplication, Part III: Customizing Vector by Edward Kmett Domain: fpcomplete.com, Score: 33, Comments: 1 On Reddit: [13] http://goo.gl/hfoJJ7 Original: [14] http://goo.gl/yLUSWP * Great new platform to increase *practical* code literacy (with Haskell support). Domain: mdswanson.com, Score: 29, Comments: 13 On Reddit: [15] http://goo.gl/sFLBQm Original: [16] http://goo.gl/TIJPTi * Bartosz' basic Haskell: Error Handling Domain: fpcomplete.com, Score: 28, Comments: 4 On Reddit: [17] http://goo.gl/1jBaWG Original: [18] http://goo.gl/zZrPxH * A Pragmatic Case for Static Typing with Brian Hurt on Vimeo (at NY-Haskell) Domain: vimeo.com, Score: 27, Comments: 11 On Reddit: [19] http://goo.gl/uECaaB Original: [20] http://goo.gl/59c8Wo * Write yourself a Brainfuck in an hour Domain: github.com, Score: 26, Comments: 13 On Reddit: [21] http://goo.gl/lAfzRf Original: [22] http://goo.gl/cbJZ7t Top StackOverflow Questions * Is it possible to lazily traverse a recursive data-structure with O(1) memory usage, tail-call optimized? votes: 10, answers: 4 Read on SO: [23] http://goo.gl/1qsBKq * pattern matching of the form: Option{..} <- votes: 10, answers: 1 Read on SO: [24] http://goo.gl/HY3FWY Until next time, [25]+Daniel Santa Cruz References 1. http://ocharles.org.uk/blog/posts/2013-08-18-asteroids-in-netwire.html 2. http://www.reddit.com/r/haskell/comments/1kmes7/building_an_asteroids_clone… 3. http://coldwa.st/e/blog/2013-08-21-Cabal-1-18.html 4. http://www.reddit.com/r/haskell/comments/1kslyi/whats_new_in_cabal_118_sand… 5. http://coldwa.st/e/blog/2013-08-20-Cabal-sandbox.html 6. http://www.reddit.com/r/haskell/comments/1kpynl/an_introduction_to_cabal_sa… 7. http://apfelmus.nfshost.com/blog/2013/08/21-space-invariants.html 8. http://www.reddit.com/r/haskell/comments/1ksu0v/reasoning_about_space_leaks… 9. https://www.fpcomplete.com/user/edwardk/bound 10. http://www.reddit.com/r/haskell/comments/1knvz2/bound_making_de_bruijn_succ… 11. http://ghc.haskell.org/trac/ghc/wiki/PatternSynonyms 12. http://www.reddit.com/r/haskell/comments/1kmods/patternsynonyms_ghc_trac/ 13. https://www.fpcomplete.com/user/edwardk/revisiting-matrix-multiplication-pa… 14. http://www.reddit.com/r/haskell/comments/1kmvs2/revisiting_matrix_multiplic… 15. http://mdswanson.com/blog/2013/08/19/how-to-practice-code-reviews.html 16. http://www.reddit.com/r/haskell/comments/1krc6t/great_new_platform_to_incre… 17. https://www.fpcomplete.com/user/bartosz/basics-of-haskell/10_Error_Handling 18. http://www.reddit.com/r/haskell/comments/1ksjt4/bartosz_basic_haskell_error… 19. https://vimeo.com/72870631 20. http://www.reddit.com/r/haskell/comments/1kusbt/a_pragmatic_case_for_static… 21. https://github.com/quchen/articles/blob/master/write_yourself_a_brainfuck.md 22. http://www.reddit.com/r/haskell/comments/1kz39d/write_yourself_a_brainfuck_… 23. http://stackoverflow.com/questions/18345734/is-it-possible-to-lazily-traver… 24. http://stackoverflow.com/questions/18372188/pattern-matching-of-the-form-op… 25. https://plus.google.com/105107667630152149014/about

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please improve this code - thanks
by Me 24 Aug '13

24 Aug '13

Hi all. I'm new to haskell. I have a puny piece of code: import Data.List.Split padL :: Int -> String -> String padL n s | length s < n = replicate (n - length s) '0' ++ s | otherwise = s strInc :: String -> String -> String strInc sep str = let strarr = splitOn sep str zprefix = strarr !! 0 znumber = strarr !! 1 in zprefix ++ sep ++ padL ( length (znumber) ) ( show ( read ( znumber ) + 1 ) ) Prelude> :l strinc [1 of 1] Compiling Main ( strinc.hs, interpreted ) Ok, modules loaded: Main. *Main> strInc "-" "xs-00009" "xs-00010" *Main> strInc "<>" "yxs<>000099" "yxs<>000100" Is it good haskell, bad haskell or average haskell? How can it be rewritten? Thanks.

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Haskell Weekly News: Issue 277
by Daniel Santa Cruz 22 Aug '13

22 Aug '13

Welcome to issue 277 of the HWN, an issue covering crowd-sourced bits of information about Haskell from around the web. This issue covers the week of August 11 to 17, 2013. Quotes of the Week * psygnisfive: Seminearring is the task of giving seminars. * Taneb: You know you've made it when SPJ asks you for help with Haskell. * byorgey: . o O ( "For my next trick, I will CPS-encode this rabbit!" -- edwardk ) * shachaf: I prefer the cogolden rule: When CPS-transforming, doubt. * edwardk: "You see these scars? I got them back in 7.7." * danharaj: parsing is hard, let's go shopping Top Reddit Stories * Mio: A High-Performance Multicore IO Manager for GHC [pdf] Domain: haskell.cs.yale.edu, Score: 147, Comments: 31 On Reddit: [1] http://goo.gl/ZTy1Yl Original: [2] http://goo.gl/6foNWC * Destroying Performance with Strictness Domain: neilmitchell.blogspot.ru, Score: 92, Comments: 45 On Reddit: [3] http://goo.gl/1rkx3a Original: [4] http://goo.gl/rb5UnM * A great series of posts on the power of monoids Domain: self.haskell, Score: 78, Comments: 10 On Reddit: [5] http://goo.gl/TmAAwT Original: [6] http://goo.gl/TmAAwT * Cellular Automata by Edward Kmett Domain: fpcomplete.com, Score: 69, Comments: 7 On Reddit: [7] http://goo.gl/EIFK5A Original: [8] http://goo.gl/03mNhV * Elm 0.9 - New type checker, much better error messages Domain: elm-lang.org, Score: 50, Comments: 14 On Reddit: [9] http://goo.gl/ngSBPX Original: [10] http://goo.gl/4Jp3l6 * Revisiting Matrix Multiplication, Part I by Edward Kmett Domain: fpcomplete.com, Score: 45, Comments: 4 On Reddit: [11] http://goo.gl/gYfm5S Original: [12] http://goo.gl/bg75ZX * Revisiting Matrix Multiplication, Part II by Edward Kmett Domain: fpcomplete.com, Score: 37, Comments: 9 On Reddit: [13] http://goo.gl/qU2r69 Original: [14] http://goo.gl/5cRq72 * Roles: a new feature of GHC (patch GND + type families) Domain: typesandkinds.wordpress.com, Score: 34, Comments: 28 On Reddit: [15] http://goo.gl/HhVOTu Original: [16] http://goo.gl/Twx5YB * Type Inference, Haskell and Dependent Types :: PDF Domain: personal.cis.strath.ac.uk, Score: 33, Comments: 0 On Reddit: [17] http://goo.gl/MbtYGO Original: [18] http://goo.gl/uOx01F * Embedded Languages for High-Performance Computing [Chakravarty, PDF 70 slides] Domain: speakerdeck.com, Score: 31, Comments: 4 On Reddit: [19] http://goo.gl/mb2frN Original: [20] http://goo.gl/EEG0Wk * Graph drawing with gloss Domain: mazzo.li, Score: 30, Comments: 7 On Reddit: [21] http://goo.gl/j0CZmo Original: [22] http://goo.gl/5ZtFuu * Benchmarking sqlite-simple against Python and C Domain: nurpax.github.io, Score: 28, Comments: 9 On Reddit: [23] http://goo.gl/CNyjWa Original: [24] http://goo.gl/gFmWgT * What is "lifting"? Explained on stackoverflow Domain: stackoverflow.com, Score: 25, Comments: 7 On Reddit: [25] http://goo.gl/HzXWb9 Original: [26] http://goo.gl/hQxTce * GHC API: Interpreted, compiled and package modules Domain: parenz.wordpress.com, Score: 23, Comments: 0 On Reddit: [27] http://goo.gl/xUeUYq Original: [28] http://goo.gl/llQsyE * Time to start writing on the new binding: SDL 2.0 release. Domain: lists.libsdl.org, Score: 22, Comments: 15 On Reddit: [29] http://goo.gl/G0ut36 Original: [30] http://goo.gl/MuO1uB * FP Complete's Haskell programming competition now accepting entries Domain: fpcomplete.com, Score: 21, Comments: 7 On Reddit: [31] http://goo.gl/tbEBKG Original: [32] http://goo.gl/ADsrJ * Pretext by experiments and guesses Domain: fpcomplete.com, Score: 18, Comments: 15 On Reddit: [33] http://goo.gl/oVpKIe Original: [34] http://goo.gl/2PFthz Top StackOverflow Questions * Haskell random numbers suddenly start to “converge” after months of running votes: 30, answers: 1 Read on SO: [35] http://goo.gl/oxUAQ5 * Why does ghc generate so many useless-looking nested case expressions? votes: 10, answers: 1 Read on SO: [36] http://goo.gl/6cdTd1 Until next time, [37]+Daniel Santa Cruz References 1. http://haskell.cs.yale.edu/wp-content/uploads/2013/08/hask035-voellmy.pdf 2. http://www.reddit.com/r/haskell/comments/1k6fsl/mio_a_highperformance_multi… 3. http://neilmitchell.blogspot.ru/2013/08/destroying-performance-with-strictn… 4. http://www.reddit.com/r/haskell/comments/1ker84/destroying_performance_with… 5. http://www.reddit.com/r/haskell/comments/1ka4q6/a_great_series_of_posts_on_… 6. http://www.reddit.com/r/haskell/comments/1ka4q6/a_great_series_of_posts_on_… 7. https://www.fpcomplete.com/user/edwardk/cellular-automata 8. http://www.reddit.com/r/haskell/comments/1kj5zh/cellular_automata_by_edward… 9. http://elm-lang.org/blog/announce/version-0.9.elm 10. http://www.reddit.com/r/haskell/comments/1ka0ld/elm_09_new_type_checker_muc… 11. https://www.fpcomplete.com/user/edwardk/revisiting-matrix-multiplication-pa… 12. http://www.reddit.com/r/haskell/comments/1kecqt/revisiting_matrix_multiplic… 13. https://www.fpcomplete.com/user/edwardk/revisiting-matrix-multiplication-pa… 14. http://www.reddit.com/r/haskell/comments/1khu61/revisiting_matrix_multiplic… 15. http://typesandkinds.wordpress.com/2013/08/15/roles-a-new-feature-of-ghc/ 16. http://www.reddit.com/r/haskell/comments/1kgivs/roles_a_new_feature_of_ghc_… 17. https://personal.cis.strath.ac.uk/adam.gundry/thesis/ 18. http://www.reddit.com/r/haskell/comments/1k6g0w/type_inference_haskell_and_… 19. https://speakerdeck.com/mchakravarty/embedded-languages-for-high-performanc… 20. http://www.reddit.com/r/haskell/comments/1kc9j1/embedded_languages_for_high… 21. http://mazzo.li/posts/graph-drawing.html 22. http://www.reddit.com/r/haskell/comments/1kb36j/graph_drawing_with_gloss/ 23. http://nurpax.github.io/posts/2013-08-17-sqlite-simple-benchmarking.html 24. http://www.reddit.com/r/haskell/comments/1kjpwz/benchmarking_sqlitesimple_a… 25. http://stackoverflow.com/questions/2395697/haskell-newbie-question-what-is-… 26. http://www.reddit.com/r/haskell/comments/1k7i4c/what_is_lifting_explained_o… 27. http://parenz.wordpress.com/2013/08/17/ghc-api-interpreted-compiled-and-pac… 28. http://www.reddit.com/r/haskell/comments/1kjl3h/ghc_api_interpreted_compile… 29. http://lists.libsdl.org/pipermail/sdl-libsdl.org/2013-August/089854.html 30. http://www.reddit.com/r/haskell/comments/1k9wh8/time_to_start_writing_on_th… 31. https://www.fpcomplete.com/business/competition/competition-overview 32. http://www.reddit.com/r/haskell/comments/1k8ox7/fp_completes_haskell_progra… 33. https://www.fpcomplete.com/user/tel/pretext-by-experiments-and-guesses 34. http://www.reddit.com/r/haskell/comments/1kkoup/pretext_by_experiments_and_… 35. http://stackoverflow.com/questions/18200283/haskell-random-numbers-suddenly… 36. http://stackoverflow.com/questions/18192184/why-does-ghc-generate-so-many-u… 37. https://plus.google.com/105107667630152149014/about

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ANN: Google co-sponsoring ZuriHac 2013
by Bas van Dijk 21 Aug '13

21 Aug '13

Dear Haskellers, I would like to remind you that the Zurich FP Afternoon (with a keynote by Simon Marlow) is taking place next week (13:00, Thursday, 29 August) and is directly followed by the ZuriHac 2013 Haskell Hackathon [1]. There are still some places available at both events -- you're welcome to register at: http://bit.ly/ZuriHac2013Reg Google Switzerland will co-sponsor the FP Afternoon and ZuriHac 2013 together with ETH Zurich and Erudify. Their sponsorship means we can give each attendee a free t-shirt (picture on the wikipage [2]) and free food and drinks during the FP Afternoon. Google is also offering a quiz during the FP Afternoon with prizes including a Galaxy S4 mini. I hope to see you there! Bas [1] http://www.haskell.org/haskellwiki/ZuriHac2013 [2] http://www.haskell.org/haskellwiki/ZuriHac2013#News

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ANNOUNCE: posix-paths, for faster file system operations
by Niklas Hambüchen 21 Aug '13

21 Aug '13

John Lato and I would like to announce our posix-paths package. https://github.com/JohnLato/posix-paths It implements a large portion of System.Posix.FilePath using ByteString based RawFilePaths instead of String based FilePaths, and on top of that provides a Traversal module with a fast replacement for `getDirectoryContents` and a recursive `allDirectoryContents`. `getDirectoryContents` is (unsurprisingly?) really slow. Our replacement is 11 times faster in the recursive use case [1], and only 20% slower than `find`. Benchmarks are at [2], code is at [3]. We hope that these improvements will eventually make it into base some day. Until then, we propose our package as a base for discussion and further improvements. Contributions are welcome: Some FilePath operations are not in it yet (especially the Windows / drive related ones), and our traversals might not work on Windows. We would also appreciate some thorough looks at their low level implementations. If you find our benchmarks against getDirectoryContents unfair or would like to add another one, please send a pull request. We have been running this on Linux production machines for a few months now, and are pleased by the speed-up. [1] For the recursive version of the original `getDirectoryContents`, we used the implementation given in Real World Haskell: http://book.realworldhaskell.org/read/io-case-study-a-library-for-searching… [2] Benchmarks: On a real file system: http://johnlato.github.io/posix-paths/usrLocal.html On tmpfs: http://johnlato.github.io/posix-paths/tmpfs.html (note that here find is slow because of process starting overhead) [3] Code: Github: https://github.com/JohnLato/posix-paths RawFilePath operations: https://github.com/JohnLato/posix-paths/blob/master/src/System/Posix/FilePa… Traversals: https://github.com/JohnLato/posix-paths/blob/master/src/System/Posix/Direct… Benchmarks: https://github.com/JohnLato/posix-paths/blob/master/benchmarks/Bench.hs

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