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Fwd: PhD/Postdoc in programming models for heterogeneous infrastructures
by Ivan Perez 26 Oct '13

26 Oct '13

Hoi hoi, haskellers! Our friends from UPM just sent the following PhD/Postdoc offer. Goed weekend!! Ivan -- The Universidad Politécnica de Madrid (www.upm.es/internacional) have an opening at the Ph.D. or post-doctoral levels within the 3-year POLCA (Programming Large Scale Heterogeneous Infrastructures) European project. POLCA aims at developing a methodology and tools to support a programming model to efficiently exploit heterogeneous computing infrastructures (CPUs / GPUs / ASICs / FPGAs) while reducing the burden on the programmer and the need to port code between architectures. The project will build upon the design and use of high-level source code annotations ("pragmas") which describe code properties which can then be used to perform aggressive, mathematically sound, source-to-source transformations capable to adapt the code to the target architecture. We seek applicants with a strong background in some of the following fields: * Source-to-source program transformation for optimization and parallelism. * Algebra of programming. * High-level architectural and system-design languages (such as Clash or ForSyDe). * Analysis of functional and non-functional program properties. Knowledge in the following topics will be a strong plus: - Existing compiler infrastructures (LLVM / Clang / ...). - Abstract syntax. - Embedded domain specific languages. - Meta-programming. - CPUs, GPUs, ASICs or FPGAs programming. Successful applicants are expected to actively contribute to the development of the project toolset and must have an interest to carry research at the intersection between specifications, programming languages, program transformation, and parallelism. Collaboration in usual EU research project chores is also expected. All positions are initially for one year, renewable for up to three years (in total), contingent on the availability of funds. Other mutually agreed arrangements are possible. In any case, satisfactory progress will be monitored and required for renewal. The starting date is negotiable, but preference may be given to candidates able to adapt to the project starting dates. For further information, please contact Ángel Herranz (aherranz at fi.upm.es). Applying -------- Candidates are kindly asked to send an email to Ángel Herranz (aherranz at fi.upm.es) with the following content: - A PDF (max size 5Mb) or plain text file containing their Research statement. - A PDF file containing their CV (max size: 5Mb). - A list of names and contact data of persons that can provide references about you and their work. Applications must be received by November 17th, 2013 to receive full consideration. However, applications will continue to be accepted until the positions are filled. Salary ------ An internationally competitive salary will be offered, negotiated with the candidate. Selected candidates will have access to an excellent public healthcare system. Work Environment ---------------- UPM team in the POLCA project will work in close collaboration with the IMDEA Software Institute (software.imdea.org) The School of Computer Science of the UPM and the IMDEA Software Institute are located in the vibrant area of Madrid, Spain, and offer an ideal working environment where researchers can focus on developing new ideas and projects. The working language is English. UPM is Equal Opportunity Employers and strongly encourage applications from a diverse and international community. Both comply with the European Charter for Researchers.

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Trouble installing haskeline: ExitFailure 139
by David Banas 26 Oct '13

26 Oct '13

Has anyone else hit an unexplained *ExitFailure 139* when trying to install the *haskeline* package? Thanks, -db dbanas@dbanas-lap:~/prj$ cabal install -v haskeline Reading available packages... Choosing modular solver. Resolving dependencies... Extracting /home/dbanas/.cabal/packages/ hackage.haskell.org/haskeline/0.7.0.3/haskeline-0.7.0.3.tar.gz to /tmp/haskeline-0.7.0.3-16574... creating /tmp/haskeline-0.7.0.3-16574/haskeline-0.7.0.3/dist/setup creating /tmp/haskeline-0.7.0.3-16574/haskeline-0.7.0.3/dist creating /tmp/haskeline-0.7.0.3-16574/haskeline-0.7.0.3/dist/setup /usr/local/bin/ghc --make /tmp/haskeline-0.7.0.3-16574/haskeline-0.7.0.3/Setup.hs -o /tmp/haskeline-0.7.0.3-16574/haskeline-0.7.0.3/dist/setup/setup -odir /tmp/haskeline-0.7.0.3-16574/haskeline-0.7.0.3/dist/setup -hidir /tmp/haskeline-0.7.0.3-16574/haskeline-0.7.0.3/dist/setup -i -i/tmp/haskeline-0.7.0.3-16574/haskeline-0.7.0.3 -package Cabal-1.16.0 [1 of 1] Compiling Main ( /tmp/haskeline-0.7.0.3-16574/haskeline-0.7.0.3/Setup.hs, /tmp/haskeline-0.7.0.3-16574/haskeline-0.7.0.3/dist/setup/Main.o ) Linking /tmp/haskeline-0.7.0.3-16574/haskeline-0.7.0.3/dist/setup/setup ... /tmp/haskeline-0.7.0.3-16574/haskeline-0.7.0.3/dist/setup/setup configure --verbose=2 --ghc --prefix=/home/dbanas/.cabal --user --flags=terminfo --flags=-libiconv --flags=-legacy-encoding --constraint=unix ==2.6.0.1 --constraint=transformers ==0.3.0.0 --constraint=terminfo ==0.3.2.5 --constraint=filepath ==1.3.0.1 --constraint=directory ==1.2.0.1 --constraint=containers ==0.5.0.0 --constraint=bytestring ==0.10.0.2 --constraint=base ==4.6.0.1 --disable-tests --disable-benchmarks World file is already up to date. cabal: Error: some packages failed to install: haskeline-0.7.0.3 failed during the configure step. The exception was: ExitFailure 139 dbanas@dbanas-lap:~/prj$

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Weird issue with ConstraintKinds
by Jacques Carette 26 Oct '13

26 Oct '13

Consider the following (minimal, for illustration purposes) code: {-# LANGUAGE ConstraintKinds #-} module Weird where class A a where class B b where class C c where data X a = X a data Y a = Y a -- works fine, but can be verbose when things multiply instance (A a, B a) => C (X a) where -- So use ConstraintKinds: type D a = (A a, B a) instance D a => C (Y a) where ===== and now I get Variable `a' occurs more often than in the instance head in the constraint: D a (Use -XUndecidableInstances to permit this) In the instance declaration for `C (Y a)' Why?? Since D is an abbreviation, why would it behave differently than when I hand expand it? [This is with GHC 7.6.3] Jacques

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ANNOUNCE: Ajhc Haskell Compiler 0.8.0.9 Release
by Kiwamu Okabe 26 Oct '13

26 Oct '13

We are happy to announce Ajhc 0.8.0.9. This version is a point release to fix some BUGs, and support Android NDK platform. You can get Ajhc using "cabal install ajhc" command. The usage is found at Ajhc's project web site http://ajhc.metasepi.org/. The source code at https://github.com/ajhc/ajhc. Welcome sending any bugs or your ideas to https://github.com/ajhc/ajhc/issues. ## Support new platforms ### Android NDK http://developer.android.com/tools/sdk/ndk/index.html The demo movie at http://www.youtube.com/watch?v=n6cepTfnFoo. The touchable cube application is written with Haskell and compiled by Ajhc. In the demo, the application is breaked by ndk-gdb debugger when running GC. You could watch the demo source code at \url{https://github.com/ajhc/demo-android-ndk}. ## Other changes * Experimental support Mac OS X to compile Ajhc and use it. * Start to run buid test for Mac OS X on Travis CI. https://travis-ci.org/ajhc/ajhc/builds/12218394 * Depend on derive package. But near future use DrIFT again. For Haskell 98 compliant. https://github.com/ajhc/ajhc/issues/47 * Fix the bugs forgetting to clear memory. Enjoy! :) - - - Metasepi team

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Horray, a ghc bug!
by Andreas Abel 25 Oct '13

25 Oct '13

You do not get them often, but here is one... [208 of 254] Compiling Agda.TypeChecking.MetaVars.Occurs ( src/full/Agda/TypeChecking/MetaVars/Occurs.hs, dist/build/Agda/TypeChecking/MetaVars/Occurs.o ) ghc: panic! (the 'impossible' happened) (GHC version 7.4.1 for x86_64-unknown-linux): compiler/rename/RnSource.lhs:429:14-81: Irrefutable pattern failed for pattern Data.Maybe.Just (inst_tyvars, _, SrcLoc.L _ cls, _) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug -- Andreas Abel <>< Du bist der geliebte Mensch. Theoretical Computer Science, University of Munich Oettingenstr. 67, D-80538 Munich, GERMANY andreas.abel(a)ifi.lmu.de http://www2.tcs.ifi.lmu.de/~abel/

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Trouble w/ ExitFailure 139 (Segmentation Fault), during Cabal installs.
by David Banas 25 Oct '13

25 Oct '13

Hi all, Prolog: I have installed GHC v7.6.3, from source, on Ubuntu 13.0.4. I think I've made my GHC v7.6.3 installation unstable, because I'm having lots of trouble with "ExitFailure 139"s when cabal installing. And I'm wondering if this is a pertinent clue: dbanas@dbanas-lap:~/prj/plush$ cabal unpack lifted-base Unpacking to lifted-base-0.2.1.0/ dbanas@dbanas-lap:~/prj/plush$ pushd lifted-base-0.2.1.0/ ~/prj/plush/lifted-base-0.2.1.0 ~/prj/plush ~ dbanas@dbanas-lap:~/prj/plush/lifted-base-0.2.1.0$ ghc --make Setup.hs [1 of 1] Compiling Main ( Setup.hs, Setup.o ) Linking Setup ... dbanas@dbanas-lap:~/prj/plush/lifted-base-0.2.1.0$ ./Setup configure Segmentation fault (core dumped) dbanas@dbanas-lap:~/prj/plush/lifted-base-0.2.1.0$ head Setup.hs #! /usr/bin/env runhaskell {-# LANGUAGE NoImplicitPrelude, UnicodeSyntax #-} module Main (main) where ------------------------------------------------------------------------------- -- Imports ------------------------------------------------------------------------------- dbanas@dbanas-lap:~/prj/plush/lifted-base-0.2.1.0$ chmod 755 Setup.hs dbanas@dbanas-lap:~/prj/plush/lifted-base-0.2.1.0$ ./Setup.hs configure Configuring lifted-base-0.2.1.0... Setup.hs: At least the following dependencies are missing: base-unicode-symbols >=0.1.1 && <0.3, monad-control ==0.3.*, transformers-base ==0.4.* dbanas@dbanas-lap:~/prj/plush/lifted-base-0.2.1.0$ What I'm attempting to call attention too, with the above excerpt, is this: *If I compile and run "Setup configure" I get a core dump, but if I just run "Setup.hs configure" (taking advantage of the fact that Setup.hs begins with a shebang line) it works fine.* Is this a clue as to how I've horked up my ghc installation? Thanks! -db

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to make a statically known sized non-empty list
by Markus Läll 25 Oct '13

25 Oct '13

Hi haskell-cafe, so for fun and profit I was trying to make a non-empty list data type, where the size of the non-empty prefix would be known for the type-system with the following code, but it fails with an error "No instance for (Functor (NonEmpty * a)) ..." for the last line. To me it seems that all should be known, but something must be missing.. data Nat = Zero | Succ Nat data family NonEmpty (n :: Nat) a data instance NonEmpty Zero a = Tail [a] data instance NonEmpty (Succ n) a = Head a (NonEmpty n a) instance Functor (NonEmpty Zero) where fmap f (Tail xs) = Tail (fmap f xs) instance Functor (NonEmpty (Succ a)) where fmap f (Head x xs) = Head (f x) (fmap f xs) -- Markus Läll

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Haskell Weekly News: Issue 284
by Daniel Santa Cruz 25 Oct '13

25 Oct '13

Welcome to issue 284 of the HWN, an issue covering crowd-sourced bits of information about Haskell from around the web. This issue covers the week of October 13 to 19, 2013. Quotes of the Week * Polarina: Once you get something with [lens] to work correctly, all other Haskell code looks like C++ in comparison. Top Reddit Stories * The GHC October status report - a nice summary of what to expect from 7.8 Domain: ghc.haskell.org, Score: 106, Comments: 51 On Reddit: [1] http://goo.gl/ZOYHI7 Original: [2] http://goo.gl/1PM4s7 * Haskell for all: An all-atom protein search engine powered by Haskell Domain: haskellforall.com, Score: 84, Comments: 51 On Reddit: [3] http://goo.gl/TwntnD Original: [4] http://goo.gl/4WbmZp * FSF - Recognizing an inspiring woman for Ada Lovelace Day: Haskell/Perl hacker Audrey Tang Domain: fsf.org, Score: 82, Comments: 15 On Reddit: [5] http://goo.gl/XbrLS7 Original: [6] http://goo.gl/zGTnbL * Automatic SIMD Vectorization for Haskell and ICFP 2013 Domain: dorchard.wordpress.com, Score: 50, Comments: 3 On Reddit: [7] http://goo.gl/ikP8nw Original: [8] http://goo.gl/kYCQyW * A Little Lens Starter Tutorial - School of Haskell Domain: fpcomplete.com, Score: 49, Comments: 43 On Reddit: [9] http://goo.gl/RQjC2m Original: [10] http://goo.gl/LA7fUo * Abstractions for the Functional Roboticist with Anthony Cowley at NY Haskell Domain: vimeo.com, Score: 43, Comments: 13 On Reddit: [11] http://goo.gl/f4j0CP Original: [12] http://goo.gl/pSZBNR * The "magic" of "join (,)" Domain: self.haskell, Score: 42, Comments: 18 On Reddit: [13] http://goo.gl/oVjtNL Original: [14] http://goo.gl/oVjtNL * A Taste of Agda with Francesco Mazzoli at NY Haskell Domain: vimeo.com, Score: 41, Comments: 15 On Reddit: [15] http://goo.gl/anu7xJ Original: [16] http://goo.gl/vIfDNM * [Demo movie] Ajhc Haskell compiler can create Haskell Apps running on Android NDK! Domain: youtube.com, Score: 36, Comments: 22 On Reddit: [17] http://goo.gl/HM4AJ3 Original: [18] http://goo.gl/j1Gmqi * Open question: help me design a new encoding API for aeson Domain: serpentine.com, Score: 31, Comments: 30 On Reddit: [19] http://goo.gl/CE6Q0I Original: [20] http://goo.gl/ikdO5O * Made some Haskell Wallpapers, thought I'd share Domain: imgur.com, Score: 30, Comments: 27 On Reddit: [21] http://goo.gl/A1LILP Original: [22] http://goo.gl/c054gN * How to use Travis-CI with multiple GHC versions Domain: github.com, Score: 30, Comments: 6 On Reddit: [23] http://goo.gl/hsH9a7 Original: [24] http://goo.gl/K2Eja5 * A Gentle Introduction to Parsec Domain: blog.barrucadu.co.uk, Score: 29, Comments: 1 On Reddit: [25] http://goo.gl/GHUil8 Original: [26] http://goo.gl/21xyq2 * Haskell.org committee is looking for self-nominations Domain: haskell.org, Score: 28, Comments: 2 On Reddit: [27] http://goo.gl/B3pc80 Original: [28] http://goo.gl/19dZX4 * Backpropogation, Steepest Descent, and Automatic Differentiation Domain: idontgetoutmuch.wordpress.com, Score: 23, Comments: 22 On Reddit: [29] http://goo.gl/izxqMg Original: [30] http://goo.gl/F2fjNk * Anonymous records. A solution to the problems of record-system. Domain: gist.github.com, Score: 22, Comments: 24 On Reddit: [31] http://goo.gl/CjdbT3 Original: [32] http://goo.gl/UY5OqT Top StackOverflow Questions * Is there a canonical haskell type for “One or Both”? votes: 15, answers: 3 Read on SO: [33] http://goo.gl/yn8MkJ * Show progress of Haskell program votes: 14, answers: 4 Read on SO: [34] http://goo.gl/IEegAQ * Does Data.ByteString.readFile block all threads? votes: 13, answers: 3 Read on SO: [35] http://goo.gl/5X805o * Am I abusing unsafePerformIO? votes: 11, answers: 3 Read on SO: [36] http://goo.gl/SnfOcK * GHCJS: How do I import a high order javascript function using FFI? votes: 10, answers: 1 Read on SO: [37] http://goo.gl/fCbPE2 * Simulating a spring/damper system in Yampa votes: 9, answers: 1 Read on SO: [38] http://goo.gl/zQ50Ao Until next time, [39]+Daniel Santa Cruz References 1. http://ghc.haskell.org/trac/ghc/wiki/Status/Oct13 2. http://www.reddit.com/r/haskell/comments/1opw22/the_ghc_october_status_repo… 3. http://www.haskellforall.com/2013/10/an-all-atom-protein-search-engine.html 4. http://www.reddit.com/r/haskell/comments/1oc5g5/haskell_for_all_an_allatom_… 5. https://www.fsf.org/blogs/community/recognizing-an-inspiring-woman-for-ada-… 6. http://www.reddit.com/r/haskell/comments/1oj2u4/fsf_recognizing_an_inspirin… 7. http://dorchard.wordpress.com/2013/10/14/automatic-simd-vectorization-for-h… 8. http://www.reddit.com/r/haskell/comments/1og58l/automatic_simd_vectorizatio… 9. https://www.fpcomplete.com/user/tel/a-little-lens-starter-tutorial 10. http://www.reddit.com/r/haskell/comments/1obpxb/a_little_lens_starter_tutor… 11. http://vimeo.com/rickasaurus/haskell-robots 12. http://www.reddit.com/r/haskell/comments/1oo2at/abstractions_for_the_functi… 13. http://www.reddit.com/r/haskell/comments/1olk04/the_magic_of_join/ 14. http://www.reddit.com/r/haskell/comments/1olk04/the_magic_of_join/ 15. https://vimeo.com/77168227 16. http://www.reddit.com/r/haskell/comments/1oq0dt/a_taste_of_agda_with_france… 17. http://www.youtube.com/watch?v=n6cepTfnFoo 18. http://www.reddit.com/r/haskell/comments/1oq22l/demo_movie_ajhc_haskell_com… 19. http://www.serpentine.com/blog/2013/10/14/open-question-help-me-design-a-ne… 20. http://www.reddit.com/r/haskell/comments/1ohe9m/open_question_help_me_desig… 21. http://imgur.com/a/DRdNi 22. http://www.reddit.com/r/haskell/comments/1om4ie/made_some_haskell_wallpaper… 23. https://github.com/hvr/multi-ghc-travis 24. http://www.reddit.com/r/haskell/comments/1os3f6/how_to_use_travisci_with_mu… 25. http://blog.barrucadu.co.uk/2013/05/27/a-gentle-introduction-to-parsec/ 26. http://www.reddit.com/r/haskell/comments/1ojsi4/a_gentle_introduction_to_pa… 27. http://www.haskell.org/pipermail/haskell-cafe/2013-October/110997.html 28. http://www.reddit.com/r/haskell/comments/1onnab/haskellorg_committee_is_loo… 29. http://idontgetoutmuch.wordpress.com/2013/10/13/backpropogation-is-just-ste… 30. http://www.reddit.com/r/haskell/comments/1odmk1/backpropogation_steepest_de… 31. https://gist.github.com/nikita-volkov/6977841 32. http://www.reddit.com/r/haskell/comments/1oicmu/anonymous_records_a_solutio… 33. http://stackoverflow.com/questions/19413438/is-there-a-canonical-haskell-ty… 34. http://stackoverflow.com/questions/19343695/show-progress-of-haskell-program 35. http://stackoverflow.com/questions/19347907/does-data-bytestring-readfile-b… 36. http://stackoverflow.com/questions/19371636/am-i-abusing-unsafeperformio 37. http://stackoverflow.com/questions/19415306/ghcjs-how-do-i-import-a-high-or… 38. http://stackoverflow.com/questions/19461227/simulating-a-spring-damper-syst… 39. https://plus.google.com/105107667630152149014/about

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mavericks + xcode 5 quick fix directions
by Carter Schonwald 24 Oct '13

24 Oct '13

Hey Everyone, I've synthesized some quick fix directions that let you use a preexisting GHC install despite the Mavericks upgrade https://gist.github.com/cartazio/7131371 please share with folks who are struggling with mavericks upgrade breaking everything :) thanks! -Carter

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Re: [Haskell-cafe] Why do I need UndecidableInstances?
by adam vogt 24 Oct '13

24 Oct '13

On Thu, Oct 24, 2013 at 11:23 AM, Stijn van Drongelen <rhymoid(a)gmail.com> wrote: > Hi, > > As far as I know, you're referring to the Paterson Conditions. Condition 'b' > kind of corresponds to "at least one of the types is shrinking", while > condition 'a' corresponds to "all the other are not growing", so the rules > are already formulated in the way you suggest. The Paterson Conditions are > also not the issue here; the Coverage Condition is. > >> The equivalent code using type families doesn't need >> undecidable instances in my ghc-7.6.2. > > > This is because (I think) type family instances are not subject to the > Coverage Condition. In principle, type families are to type classes as > functions are to relations. Functional dependencies may be used to make type > classes more 'function-like'. I guess(!) the Coverage Condition is trying to > capture this notion. > > I don't know why it's formulated in this way, because in Alejandro's > example, the classes really look 'function-like'. > > Kind regards, > > Stijn van Drongelen Hi Stijn, Thanks for clarifying the issue. There is an example of why the coverage condition is needed on line 512 of (github doesn't handle line numbers in lhs correctly unfortunately): https://github.com/ghc/ghc/blob/9a04e1c7257f93f0c1cadc56a5e2a177574f6871/co… It doesn't seem possible to write a type for that function with just a type family; you need a class Mul to get into an infinite loop while looking for instances. So it seems appropriate that the coverage condition does not apply to type families. Regards, Adam

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