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Undefined symbol error coming from shared, dynamic library.
by David Banas 14 Sep '11

14 Sep '11

Hi all, I'm trying to build a shared, dynamic library for use with a C program. I'm getting an `undefined symbol' error, when I try to run that C program, and was hoping that the last line in the output, below, might mean something to someone. I include the entire output of a `make rebuild' command, below, hoping that, maybe, I just have my command line options a little wrong. Thanks! -db dbanas@dbanas-eeepc:~/prj/haskell/AMIParse/trunk$ make rebuild make clean make[1]: Entering directory `/home/dbanas/prj/haskell/AMIParse/trunk' rm -f *.hi *.o *.out ami_test *.so make[1]: Leaving directory `/home/dbanas/prj/haskell/AMIParse/trunk' make all make[1]: Entering directory `/home/dbanas/prj/haskell/AMIParse/trunk' gcc -I/usr/lib/ghc-6.12.3/include/ -g -fPIC -c -o ami_test.o ami_test.c gcc -rdynamic -o ami_test ami_test.o -ldl ghc -c ApplicativeParsec.hs -cpp -package parsec-3.1.1 -package dsp -dynamic -fPIC ghc -c AMIParse.hs -cpp -package parsec-3.1.1 -package dsp -dynamic -fPIC ghc -c ExmplUsrModel.hs -cpp -package parsec-3.1.1 -package dsp -dynamic -fPIC ghc -c AMIModel.hs -cpp -package parsec-3.1.1 -package dsp -dynamic -fPIC gcc -I/usr/lib/ghc-6.12.3/include/ -g -fPIC -c -o ami_model.o ami_model.c rm -f libami.so ghc -o libami.so -shared -dynamic -package parsec-3.1.1 -package dsp AMIParse.o AMIModel.o ami_model.o AMIModel_stub.o ApplicativeParsec.o ExmplUsrModel.o make[1]: Leaving directory `/home/dbanas/prj/haskell/AMIParse/trunk' dbanas@dbanas-eeepc:~/prj/haskell/AMIParse/trunk$ ./ami_test test.ami /usr/lib/ghc-6.12.3/ghc-prim-0.2.0.0/libHSghc-prim-0.2.0.0-ghc6.12.3.so: undefined symbol: stg_newByteArrayzh

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Final CFP: PEPM12 - Workshop on Partial Evaluation and Program Manipulation
by oleg＠okmij.org 14 Sep '11

14 Sep '11

Final Call For Papers Paper submission deadline: Mon, October 10, 2011, 23:59, GMT ACM SIGPLAN 2012 Workshop on Partial Evaluation and Program Manipulation January 23-24, 2012. Philadelphia, Pennsylvania, USA (co-located with POPL'12) http://www.program-transformation.org/PEPM12 The PEPM Symposium/Workshop series aims to bring together researchers and practitioners working in the broad area of program transformation, which spans from refactoring, partial evaluation, supercompilation, fusion and other metaprogramming to model-driven development, program analyses including termination, inductive programming, program generation and applications of machine learning and probabilistic search. PEPM focuses on techniques, supporting theory, tools, and applications of the analysis and manipulation of programs. Each technique or tool of program manipulation should have a clear, although perhaps informal, statement of desired properties, along with an argument how these properties could be achieved. Topics of interest for PEPM'12 include, but are not limited to: - Program and model manipulation techniques such as: supercompilation, partial evaluation, fusion, on-the-fly program adaptation, active libraries, program inversion, slicing, symbolic execution, refactoring, decompilation, and obfuscation. - Program analysis techniques that are used to drive program/model manipulation such as: abstract interpretation, termination checking, binding-time analysis, constraint solving, type systems, automated testing and test case generation. - Techniques that treat programs/models as data objects including metaprogramming, generative programming, embedded domain-specific languages, program synthesis by sketching and inductive programming, staged computation, and model-driven program generation and transformation. - Application of the above techniques including case studies of program manipulation in real-world (industrial, open-source) projects and software development processes, descriptions of robust tools capable of effectively handling realistic applications, benchmarking. Examples of application domains include legacy program understanding and transformation, DSL implementations, visual languages and end-user programming, scientific computing, middleware frameworks and infrastructure needed for distributed and web-based applications, resource-limited computation, and security. To maintain the dynamic and interactive nature of PEPM, we will continue the category of `short papers' for tool demonstrations and for presentations of exciting if not fully polished research, and of interesting academic, industrial and open-source applications that are new or unfamiliar. Student attendants with accepted papers can apply for a SIGPLAN PAC grant to help cover travel expenses and other support. All accepted papers, short papers included, will appear in formal proceedings published by ACM Press and will be included in the ACM Digital Library. Selected papers may later on be invited for a journal special issue dedicated to PEPM'12. Submission Categories and Guidelines Authors are strongly encouraged to consult the advice for authoring research papers and tool papers before submitting. The PC Chairs welcome any inquiries about the authoring advice. Regular research papers must not exceed 10 pages in ACM Proceedings style. Short papers are up to 4 pages in ACM Proceedings style. Authors of tool demonstration proposals are expected to present a live demonstration of the described tool at the workshop (tool papers should include an additional appendix of up to 6 extra pages giving the outline, screenshots, examples, etc. to indicate the content of the proposed live demo at the workshop). Important Dates - Paper submission: Mon, October 10, 2011, 23:59, GMT - Author notification: Tue, November 8, 2011 - Workshop: Mon-Tue, January 23-24, 2012 Invited Speakers - Markus Pueschel (ETH Zurich, Switzerland) - Martin Berger (University of Sussex, UK) Program Chairs - Oleg Kiselyov (Monterey, CA, USA) - Simon Thompson (University of Kent, UK) Program Committee Members - Emilie Balland (INRIA, France) - Ewen Denney (NASA Ames Research Center, USA) - Martin Erwig (Oregon State University, USA) - Sebastian Fischer (National Institute of Informatics, Japan) - Lidia Fuentes (Universidad de Malaga, Spain) - John Gallagher (Roskilde University, Denmark and IMDEA Software, Spain) - Dave Herman (Mozilla Research, USA) - Stefan Holdermans (Vector Fabrics, the Netherlands) - Christian Kaestner (University of Marburg, Germany) - Emanuel Kitzelmann (International Computer Science Institute, USA) - Andrei Klimov (Keldysh Institute of Applied Mathematics, Russian Academy of Sciences) - Shin-Cheng Mu (Academia Sinica, Taiwan) - Alberto Pardo (Universidad de la Repu'blica, Uruguay) - Kostis Sagonas (Uppsala University, Sweden and National Technical University of Athens, Greece) - Anthony M. Sloane (Macquarie University, Australia) - Armando Solar-Lezama (MIT, USA) - Aaron Stump (The University of Iowa, USA) - Kohei Suenaga (University of Kyoto, Japan) - Eric Van Wyk (University of Minnesota, USA) - Kwangkeun Yi (Seoul National University, Korea)

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Haskell 101 on classes .... duh ..... :^)
by Vasili I. Galchin 14 Sep '11

14 Sep '11

Hello, I am trying to model multigraphs ....but getting errors with ghci and can't figure out why.... I have a serious blind spot .... {-# LANGUAGE MultiParamTypeClasses, FunctionalDependencies #-} module Bonzo where class Graph arrow node where source :: arrow -> node target :: arrow -> node data Arrow = Arrow (Int, Int) instance Graph Arrow Int where source Arrow = fst Arrow target Arrow = snd Arrow ~ ~ {-# LANGUAGE MultiParamTypeClasses, FunctionalDependencies #-} module Bonzo where class Graph arrow node where source :: arrow -> node target :: arrow -> node data Arrow = Arrow (Int, Int) instance Graph Arrow Int where source Arrow = fst Arrow target Arrow = snd Arrow ~ ~ ghci> :load junk1.hs [1 of 1] Compiling Bonzo ( junk1.hs, interpreted ) junk1.hs:19:12: Constructor `Arrow' should have 1 argument, but has been given 0 In the pattern: Arrow In the definition of `source': source Arrow = fst Arrow In the instance declaration for `Graph Arrow Int' junk1.hs:21:12: Constructor `Arrow' should have 1 argument, but has been given 0 In the pattern: Arrow In the definition of `target': target Arrow = snd Arrow In the instance declaration for `Graph Arrow Int' Regards, Vasili

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Question about type families
by Grigory Sarnitskiy 13 Sep '11

13 Sep '11

Is there a way to make the following code working? {-# LANGUAGE TypeFamilies #-} data family Foo a data instance (Num a) => Foo a = A a deriving Show data instance (Fractional a) => Foo a = B a deriving Show I want to have different constructors for 'Foo a' depending on a class of 'a'. Note also, that in the example above I also meant constructor A to be available for (Fractional a) => Foo, since in that case 'a' has Num too. How can I achieve it, maybe not with TypeFamilies? Current error is Conflicting family instance declarations: data instance Foo a -- Defined at 1.hs:7:33-35 data instance Foo a -- Defined at 1.hs:5:33-35

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Can't resolve class dependences (making Boolean class)
by Grigory Sarnitskiy 13 Sep '11

13 Sep '11

Hello! I'm trying to have a class for booleans called Boolean (the methods are not complete): class MyEq a where (===) :: (Boolean b) => a -> a -> b class (MyEq a) => Boolean a where (/\) :: a -> a -> a instance MyEq Bool where x === y = x==y instance Boolean Bool where (/\) = (&&) However, to make Bool an instance of Boolean I need to make it an instance of MyEq first, which I can't, because to define === I need Bool to be in Boolean. Indeed the code above give the error: Could not deduce (b ~ Bool) from the context (Boolean b) bound by the type signature for === :: Boolean b => Bool -> Bool -> b at 1.hs:8:5-18 `b' is a rigid type variable bound by the type signature for === :: Boolean b => Bool -> Bool -> b at 1.hs:8:5 In the expression: x == y In an equation for `===': x === y = x == y In the instance declaration for `MyEq Bool' Failed, modules loaded: none. How can I overcome the issue?

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extending and reusing cmdargs option specs ?
by Simon Michael 13 Sep '11

13 Sep '11

Hi Neil, I just spent a day converting hledger from getopt to cmdargs. cmdargs feels more high level and featureful and nicer. And yet... I haven't reduced the line count that much - nothing like your HLint 3:1 ratio. And, I may have made things worse for myself in the reuse/avoiding boilerplate department: I'm not sure how to reuse a cmdargs options data structure, extending it with a few more options. Using getopt I was able to do this without repeating myself (as long as I defined the full set of Opt constructors in one place.) I've looked at the more advanced cmdargs api, but don't see a way yet - would you have any ideas ? I want this because I have multiple executables (hledger, hledger-vty, hledger-web etc.) which should share most (but not all) options. Also, I'd like to move a generic subset of report options, without the ui- specific ones, into hledger-lib for use by all apps. Also, the hledger executable has multiple commands, so I'd like to define a mode for each, but not have to redeclare all the same options for each mode - I didn't see how to do that. As always, thanks a lot for cmdargs! -Simon

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Can't link OpenCL on Windows
by Jason Dagit 13 Sep '11

13 Sep '11

Hello, I'm trying to get the OpenCLRaw bindings to a point where I can use them on windows. I've forked the the OpenCLRaw repo on github so I can make modifications as needed. My branch is here: https://github.com/dagit/OpenCLRaw I've been mostly working out of my "FunPtr" branch. The issue I'm having is this: I installed AMD's OpenCL SDK, converted their Visual Studio specific .lib file to a file that gcc can handle (.a file), but ghc can't seem to link with it. I get undefined symbols for everything I use in the OpenCL API. I was able to build a "trivial" C program and link it using the .a file that I generated and gcc from mingw (not from the Haskell install). I'm using the latest windows release of the Haskell platform. These are the steps I used for generating the .a file: http://forums.amd.com/forum/messageview.cfm?catid=390&threadid=138890 I used the commands in the example script (e.g., gendef and dlltool). I've tried to use 32bit everything as much as possible, as I know that GHC will want everything to be 32bit, so I don't think it's a 32bit vs. 64bit issue. Does anyone know if there is something different about invoking gcc under ghc instead of the gcc that I get from mingw? I've also played with the ghc command line (I used cabal-dev --verbose=3 to inspect the command line) and I'm still unable to massage it into a working state. Any help would be appreciated! Thanks, Jason

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Haskell Platform Older Releases for Linux
by Luis Cabellos 12 Sep '11

12 Sep '11

Hi, I search the Haskell Platform webpage for older releases, I found it but maybe it's worth to put a table of older releases as tar.gz file with their ghc dependency, like (versions totally make up): HP 2011.2.0.0 source, March 2011. -> ghc 13.1 HP 2010.2.0.0 source, July 2010. -> ghc 3.14 HP 2010.1.0.0 source, March 2010. -> ghc 616 HP 2009.2.0.2 source, July 2009. -> ghc 1 HP 2009.2.0.1 source, June 2009. -> ghc 0 HP 2009.2.0 source, May 2009. -> ghc -1 Thanks, Luis

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Package descriptions on hackage
by Joachim Breitner 12 Sep '11

12 Sep '11

Dear hackage package authors, this is a short message from your distribution package creators: Please, if possible, write good, not too short descriptions, and also keep them up to date. Of course, users browsing hackage will benefit as well. Keep in mind that the users do not know what other packages this relates to. So if the package is part of a larger set of corresponding packages, include a general blob and then explain this particular packages. This is especially true for packages that contain the base types for a suite of packages. Also think about all the possible keywords that someone might enter in a search engine when looking for something like your package, and ideally explain how your library relates to these keywords so that the user can estimate whether it useful for him even before reading the API. Here a few negative examples, not to expose particular authors, but selected because they were the most resent that the Debian Haskell Team had packaged. ========= The http-enumerator package This package uses attoparsec for parsing the actual contents of the HTTP connection. The only gotcha is the withHttpEnumerator function, otherwise should do exactly what you expect. (A list of supported features would be great, maybe a short note what enumerator means. Also, the second sentence is incomprehensible to me and the latest version does not contain a withHttpEnumerator function any more) ========= The representable-functors package Representable functors (Clearly not helpful. Here is what Iulian came up for for the Debian package, from the individual module documentation, but I still think the author could do better This package provides a generalized Store comonad, parameterized by a Representable functor (the representation of that functor serves as the index of the store) and a generalized State monad, parameterized by a Representable functor (the representation of that functor serves as the state). Representable functors on Hask all monads, being isomorphic to a reader monad. Representable contravariant endofunctors over the category of Haskell types are isomorphic to (_ -> r) and resemble mappings to a fixed range. Representable endofunctors over the category of Haskell types are isomorphic to the reader monad and so inherit a very large number of properties for free.) ========= The data-lens package Haskell 98 Lenses (Also not helpful. And probably a very useful package! Iulian wrote „A lense is a composable notion of a purely functional field accessor.“ which is still quite short, but explains the use of the package much better) ========= The algebra package Constructive abstract algebra (Seems to be the “main” package of a series of packages. Yet another reason for having a good description. Here a suggestion, again by Iulian: “This package provides algebraic structures, such as groups, fields, rings, modules. It also provides bands, also known as idempotent semigroups (band is a semigroup where every element is equal to its own square), coalgebras, semirings (rigs), idempotent semirings, also known as dioids.“) ========= I know that most people have better things to do than to write API documentation, so it is not unexpected that, after having written the API documentation after all, they don’t spend too much time on the description. But think about it: It is the first thing possible users are going to see from your package. So if you want to attract users, do take your time to write a comprehensive and comprehensible description. Thanks, Joachim -- Joachim "nomeata" Breitner mail(a)joachim-breitner.de | nomeata(a)debian.org | GPG: 0x4743206C xmpp: nomeata(a)joachim-breitner.de | http://www.joachim-breitner.de/

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TypeOperators and Unicode
by Grigory Sarnitskiy 12 Sep '11

12 Sep '11

I want to have Unicode symbols for type operator: {-# LANGUAGE TypeOperators #-} data a ── b = Foo a b But it doesn't work. Any suggestions?

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