- Haskell-Cafe - Haskell.org

Decision procedure for foldr/foldl/foldl'?
by David Fox 22 Nov '11

22 Nov '11

Does anyone have a quick way to decide which of the fold functions to use in a given situation? There are times when I would like to find out which to use in the quickest way possible, rather than reading a long explanation of why each one behaves the way it does.

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Is SmallCheck maintained?
by Roman Cheplyaka 22 Nov '11

22 Nov '11

Hi Cafe, Does anyone currently work on Test.SmallCheck? I see the following problems: 1. SC doesn't have a repository, issue tracker etc. 2. It is not integrated with popular test frameworks 3. API should be better documented I'm willing to work on the above problems, but wanted to check first if someone's already working on them or at least has a repository. I already wrote to Colin Runciman but got no response. -- Roman I. Cheplyaka :: http://ro-che.info/

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FLOPS 2012: 2nd call for papers
by Tom Schrijvers 22 Nov '11

22 Nov '11

Second Call For Papers ===================== *Eleventh International Symposium on Functional and Logic Programming (FLOPS 2012)* May 23-25, 2012 Kobe, Japan [http://www.org.kobe-u.ac.jp/flops2012/] _Submission deadline : December 9, 2011_ FLOPS is a forum for research on all issues concerning declarative programming, including functional programming and logic programming, and aims to promote cross-fertilization and integration between the two paradigms. Previous FLOPS meetings were held in Fuji Susono (1995), Shonan Village (1996), Kyoto (1998), Tsukuba (1999), Tokyo (2001), Aizu (2002), Nara (2004), Fuji Susono (2006), Ise (2008), and Sendai (2010). Topics ====== FLOPS solicits original papers in all areas of functional and logic programming, including (but not limited to): - Declarative Pearls: new and excellent declarative programs with illustrative applications. - Language issues: language design and constructs, programming methodology, integration of paradigms, interfacing with other languages, type systems, constraints, concurrency and distributed computing. - Foundations: logic and semantics, rewrite systems and narrowing, type theory, proof systems. - Implementation issues: compilation techniques, memory management, program analysis and transformation, partial evaluation, parallelism. - Applications: case studies, real-world applications, graphical user interfaces, Internet applications, XML, databases, formal methods and model checking. The proceedings will be published as an LNCS volume. The proceedings of the previous meeting (FLOPS 2010) were published as LNCS 6009. PC co-Chairs ============ - Tom Schrijvers (Ghent University, Belgium) - Peter Thiemann (University of Freiburg, Germany) PC Members ========== - Salvador Abreu (University of Evora, Portugal) - Thorsten Altenkirch (University of Nottingham, UK) - Sebastian Brand (NICTA, Australia) - Giuseppe Castagna (CNRS Univ Paris 7, France) - Sebastian Fischer (Germany) - Marco Gavanelli (University of Ferrara, Italy) - Joxan Jaffar (National University of Singapore, Singapore) - Barry Jay (University of Sydney, Australia) - Andy King (University of Kent, UK) - Claude Kirchner (INRIA, France) - Neelakantan R. Krishnaswami (Microsoft Cambridge, UK) - Yulya Lierler (University of Kentucky, USA) - Keiko Nakata (Tallinn University of Technology, Estonia) - Peter Schneider-Kamp (University of Southern Denmark, Denmark) - Olin Shivers (Northeastern University, USA) - Paul Tarau (University of Northern Texas, USA) - Kazunori Ueda (Waseda University, Japan) - Meng Wang (Chalmers Technical University, Sweden) General Chair and Local co-Chairs ================================= - Naoyuki Tamura (Kobe University, Japan) - Mutsunori Banbara (Kobe University, Japan) - Katsutoshi Hirayama (Kobe University, Japan) Submission ========== Submissions must be unpublished and not submitted for publication elsewhere. Work that already appeared in unpublished or informally published workshops proceedings may be submitted. Submissions should fall into one of the following categories: - Regular research papers: they should describe new results and will be judged on originality, correctness, and significance. - System descriptions: they should contain a link to a working system and will be judged on originality, usefulness, and design. Submissions must be written in English and can be up to 15 pages long, though pearls are typically considerably shorter. Authors are required to use LaTeX2e and the Springer llncs class file, available at [http://www.springer.de/comp/lncs/authors.html] Regular research papers should be supported by proofs and/or experimental results. In case of lack of space, this supporting information should be made accessible otherwise (e.g., a link to a web page, or an appendix). Papers should be submitted electronically at [https://www.easychair.org/conferences/?conf=flops2012] Important Dates =============== - Submission deadline : December 9, 2011 - Author notification : February 3, 2012 - Camera-ready copy : March 2, 2012 Place and Related Events ======================== Takikawa Memorial Hall, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501 Japan. The 23rd International Conference on Rewriting Techniques and Applications (RTA 2012) and satellite workshops including WFLP 2012 will be held in the week after FLOPS at Nagoya, Japan. Some Previous FLOPS =================== - FLOPS 2010, Sendai: [http://www.kb.ecei.tohoku.ac.jp/flops2010/] - FLOPS 2008, Ise: [http://www.math.nagoya-u.ac.jp/~garrigue/FLOPS2008/] - FLOPS 2006, Fuji Susono: [http://hagi.is.s.u-tokyo.ac.jp/FLOPS2006/] Sponsors ======== - Japan Society for Software Science and Technology (JSSST) SIGPPL In Cooperation with =================== - ACM SIGPLAN - Asian Association for Foundation of Software (AAFS) - Association for Logic Programming (ALP)

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FLOPS 2012: 2nd call for papers
by Tom Schrijvers 22 Nov '11

22 Nov '11

-- prof. dr. ir. Tom Schrijvers Programming Languages Group Department of Applied Mathematics and Computer Science University of Ghent Krijgslaan 281 S9 9000 Gent Belgium Phone: +32 9 264 4805 http://users.ugent.be/~tschrijv/

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Interpreter with Cont
by oleg＠okmij.org 22 Nov '11

22 Nov '11

I would recommend Ralf Hinze's ICFP00 Pearl Deriving Backtracking Monad Transformers http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.34.4164 He starts with a monad transformer expressed as a free term algebra, and shows step-by-step how to transform it to a more efficient context-passing style. He deals with exceptions and backtracking rather than IO; the ideas are quite similar though.

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FW: [Haskell] Job Opportunity at Parallel Scientific
by Simon Peyton-Jones 22 Nov '11

22 Nov '11

I'm taking the liberty of forwarding this super-relevant advert to Haskell Cafe in case any readers read the Cafe but not the main Haskell mailing list. Simon From: haskell-bounces(a)haskell.org [mailto:haskell-bounces@haskell.org] On Behalf Of Peter Braam Sent: 21 November 2011 22:23 To: haskell Subject: [Haskell] Job Opportunity at Parallel Scientific Parallel Haskell Programmers Parallel Scientific, LLC is a Boulder, CO based early stage, but funded startup company working in the area of scalable parallelization for scientific and large data computing. We are implementing radically new software tools for the creation and optimization of parallel programs benefiting applications and leveraging modern systems architecture. We build on our mathematical knowledge, cutting edge programming languages and our understanding of systems software and hardware. We are currently working with the Haskell development team and major HPC laboratories world wide on libraries and compiler extensions for parallel programming. Parallel Scientific was founded by Dr Peter Braam in 2010. Peter formerly taught mathematics and computer science at Oxford and Carnegie Mellon. Then he contributed file systems to Linux and invented Lustre (which provides storage to 9 of the top 10 systems in the world). He ran several successful startups, and Parallel Scientific is run by an very experienced management team and board. Successful candidates can in some cases work remotely and will work in a modern virtual environment. We provide training in advanced processes for software design and implementation and domain specific knowledge. Required skills: * Very strong background in computer science or mathematics * Experience with Haskell * Knowledge of systems programming and operating systems functionality * Knowledge of system architectures, such as high performance networking, memory architectures, multi and manycore CPUs and GPGPUs * Experience with performance tuning of parallel or concurrent algorithms * Experience designing and implementing concurrent or parallel programs Experience in one or more of the following areas is desirable: * Experience with Haskell compiler technology * In depth knowledge of core Haskell libraries for parallel programming (NDP, REPA etc) * Experience in the area of middleware algorithms for data flow programming, graphs, cloud based data analytics, or sparse matrices * Domain specific knowledge in scientific programming areas related to irregular and sparse problems, e.g. data analytics using graph analysis, genomics, tightly connected numerical analysis * Experience with performance tuning for parallel applications on multi core systems (e.g. with the Intel toolkit), for GPGPU's using Cuda/OpenCL or with MPI/OpenMP on clusters of SMPs To apply, please send a resume to jobs(a)parsci.com<mailto:jobs@parsci.com>.

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ST not strict enough?
by Jason Dusek 22 Nov '11

22 Nov '11

Hi All, I'm having some trouble with memory usage in rebuilding a ByteString with some sequences escaped. I thought I'd try vectors. However, it seems that even a relatively simple function, one that places all the bytes of a ByteString in to a vector, uses a great deal of memory. I've pulled this function out into a mini-module for testing: https://github.com/solidsnack/arx/blob/ST/Rebuild.hs#L37 On a one megabyte input, it peaks at ~38M of memory: :; dd if=/dev/zero bs=1M count=1 | ./rebuildprof +RTS -s ... 38,724,208 bytes maximum residency (5 sample(s)) 1,983,720 bytes maximum slop 76 MB total memory in use (0 MB lost due to fragmentation) ... %GC time 61.3% (61.5% elapsed) A heap profile by type, with -hy, shows a linear rise in ST items -- up to ~26M -- and then a linear decrease. It would stand to reason that, with sufficient strictness, the memory allocated to ST would stay constant and small. Should I be annotating my functions with strictness, for the vector reference, for example? Should I be using STUArrays, instead? -- Jason Dusek () ascii ribbon campaign - against html e-mail /\ www.asciiribbon.org - against proprietary attachments

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Job Opportunity at Parallel Scientific
by Peter Braam 21 Nov '11

21 Nov '11

Parallel Haskell Programmers Parallel Scientific, LLC is a Boulder, CO based early stage, but funded startup company working in the area of scalable parallelization for scientific and large data computing. We are implementing radically new software tools for the creation and optimization of parallel programs benefiting applications and leveraging modern systems architecture. We build on our mathematical knowledge, cutting edge programming languages and our understanding of systems software and hardware. We are currently working with the Haskell development team and major HPC laboratories world wide on libraries and compiler extensions for parallel programming. Parallel Scientific was founded by Peter Braam in 2010. Peter formerly taught mathematics and computer science at Oxford and Carnegie Mellon. Then he contributed file systems to Linux and invented Lustre (which provides storage to 9 of the top 10 systems in the world). He ran several successful startups, and Parallel Scientific is run by an very experienced management team and board. Successful candidates can in some cases work remotely and will work in a modern virtual environment. We provide training in advanced processes for software design and implementation and domain specific knowledge. Required skills: - Very strong background in computer science or mathematics - Experience with Haskell - Knowledge of systems programming and operating systems functionality - Knowledge of system architectures, such as high performance networking, memory architectures, multi and manycore CPUs and GPGPUs - Experience with performance tuning of parallel or concurrent algorithms - Experience designing and implementing concurrent or parallel programs Experience in one or more of the following areas is desirable: - Experience with Haskell compiler technology - In depth knowledge of core Haskell libraries for parallel programming (NDP, REPA etc) - Experience in the area of middleware algorithms for data flow programming, graphs, cloud based data analytics, or sparse matrices - Domain specific knowledge in scientific programming areas related to irregular and sparse problems, e.g. data analytics using graph analysis, genomics, tightly connected numerical analysis - Experience with performance tuning for parallel applications on multi core systems (e.g. with the Intel toolkit), for GPGPU's using Cuda/OpenCL or with MPI/OpenMP on clusters of SMPs To apply, please send a resume to jobs(a)parsci.com.

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Interpreter with Cont
by Tim Baumgartner 21 Nov '11

21 Nov '11

Hi all, I wrote a simple interpreter that can be run in the console: data Interaction a b = Exit b | Output b (Interaction a b) | Input (a -> Interaction a b) runConsole :: Interaction String String -> IO () runConsole (Exit b) = putStrLn $ "Finished. Result: " ++ b runConsole (Output s cont) = putStrLn s >> runConsole cont runConsole (Input f) = putStr "> " >> getLine >>= runConsole . f interpreter :: Int -> Interaction String String interpreter i = interaction where interaction = Input input input "exit" = Exit (show i) input "inc" = Output "ok" $ interpreter (i+1) input "show" = Output (show i) interaction input "hello"= Output "Hello World!" interaction input s = Output ("Whas's '" ++ s ++ "' ?") interaction main = runConsole . Output "Known commands: show, inc, hello, exit" $ interpreter 5 I have not yet gained a good understanding of the continuation monad, but I wonder if it could be used here. What would a clean solution look like? Perhaps there are other things that need to be changed as well? Regards, Tim

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Superset of Haddock and Markdown
by Johan Tibell 21 Nov '11

21 Nov '11

Hi all, I spent some time today documenting a library and the experience left me wanting a better markup language. In particular, Haddock lacks: * markup for bold text: bold text works better than italics for emphasis on computer monitors. * hyperlinks with anchor texts: having the actual URL rendered inline with text hurts readability. Could Haddock markup be extended to also include some Markdown features? The new features could be hidden behind a flag so old documentation doesn't get unwanted markup (e.g. if it uses *...* to not mean bold). P.S. This good make a good weekend hack that shouldn't be too difficult. -- Johan

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