September 2006 - Haskell

Second CFP: Partial Evaluation and Program Manipulation (PEPM'07)
by Eelco Visser 12 Sep '06

12 Sep '06

---------------------------------------------------------------------- Second Call For Papers ACM SIGPLAN 2007 Workshop on PARTIAL EVALUATION AND PROGRAM MANIPULATION (PEPM'07) Nice, France January 15-16, 2007 (Co-located with POPL 2007) http://www.program-transformation.org/PEPM07 ---------------------------------------------------------------------- The PEPM Symposium/Workshop series aims to bring together researchers and practitioners working in the areas of program manipulation, partial evaluation, and program generation. PEPM focuses on techniques, theory, tools, and applications of analysis and manipulation of programs. The 2007 PEPM workshop will be based on a broad interpretation of semantics-based program manipulation and continue last year's successful effort to expand the scope of PEPM significantly beyond the traditionally covered areas of partial evaluation and specialization and include practical applications of program transformations such as refactoring tools, and practical implementation techniques such as rule- based transformation systems. In addition, the scope of PEPM covers manipulation and transformations of program and system representations such as structural and semantic models that occur in the context of model-driven development. In order to reach out to practitioners, a separate category of tool demonstration papers will be solicited. ---------------------------------------------------------------------- Topics of interest for PEPM'07 include, but are not limited to: + Program and model manipulation techniques such as transformations driven by rules, patterns, or analyses, partial evaluation, specialization, slicing, symbolic execution, refactoring, aspect weaving, decompilation, and obfuscation. + Program analysis techniques that are used to drive program/model manipulation such as abstract interpretation, static analysis, binding-time analysis, dynamic analysis, constraint solving, and type systems. + Analysis and transformation for programs/models with advanced features such as objects, generics, ownership types, aspects, reflection, XML type systems, component frameworks, and middleware. + Techniques that treat programs/models as data objects including meta-programming, generative programming, staged computation, and model-driven program generation and transformation. + Application of the above techniques including experimental studies, engineering needed for scalability, and benchmarking. Examples of application domains include legacy program understanding and transformation, domain-specific language implementations, scientific computing, middleware frameworks and infrastructure needed for distributed and web-based applications, resource-limited computation, and security. We especially encourage papers that break new ground including descriptions of how program/model manipulation tools can be integrated into realistic software development processes, descriptions of robust tools capable of effectively handling realistic applications, and new areas of application such as rapidly evolving systems, distributed and web-based programming including middleware manipulation, model-driven development, and on-the-fly program adaptation driven by run-time or statistical analysis. ---------------------------------------------------------------------- Submission Categories and Guidelines Regular research papers must not exceed 10 pages in ACM Proceedings style. Tool demonstration papers must not exceed 4 pages in ACM Proceedings style, and authors will be expected to present a live demonstration of the described tool at the workshop. Suggested topics, evaluation criteria, and writing guidelines for both research tool demonstration papers will be made available on the PEPM'07 web site. Papers should be submitted electronically via the workshop web site. The workshop proceedings will be published in the ACM Digital Library and selected papers will be invited for a journal special issue dedicated to PEPM'07. ---------------------------------------------------------------------- Important Dates + Abstracts due: October 18, 2006 + Submission: October 20, 2006 + Notification: December 1, 2006 + Camera-ready: December 18, 2006 + Workshop: January 15-16, 2007 ----------------------------------------------------------------------- Program Chairs * G. Ramalingam (Microsoft Research, Bangalore) * Eelco Visser (Delft University of Technology, The Netherlands) Program Committee Members * Ras Bodik (University of California, Berkeley, USA) * Albert Cohen (INRIA, France) * Jim Cordy (Queen's University, Canada) * Martin Erwig (Oregon State University, USA) * Bernd Fischer (University of Southampton, UK) * John Hatcliff (Kansas State University, USA) * Jan Heering (CWI, The Netherlands) * Dan Grossman (University of Washington, USA) * Annie Liu (State University of New York at Stony Brook, USA) * Jacques Noyé (École des Mines de Nantes/INRIA, France) * German Puebla (Technical University of Madrid, Spain) * Peter Sestoft (Royal Veterinary and Agricultural University, Denmark) * Yannis Smaragdakis (Georgia Tech, Atlanta, USA) * Walid Taha (Rice University, Houston, USA) -----------------------------------------------------------------------

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Pajama & Eros; collaborators sought
by Conal Elliott 11 Sep '06

11 Sep '06

I'm looking for collaborators on two projects, as described below. The first project is Pajama, which is a re-implementation of the Pan language and optimizing compiler for image synthesis and manipulation ( http://conal.net/Pan) The Pajama home page is http://conal.net/Pajama, and a new wiki is at http://pajama.conal.net. Pan's use was very limited, because it generated C++ code, ran only on Windows, and depended on Microsoft Visual C++ and a long-obsolete GUI library. In contrast, Pajama generates Java code and therefore runs on several platforms. Pajama-compiled effects don't run quite as fast as Pan-compiled ones, but I believe they run much faster than other functional image implementations. Besides these implementation issues, Pajama also provides a richer approach to spatial interaction and a more general notion of spatial transformation. The second project is Eros and is described in a draft paper ( http://conal.net/papers/Eros) Eros is a prototype system for end-user construction of parameterized computational content. In other words, it is a way to create programs but with the feel of interacting with the running programs. The central idea is that of tangible values, which are values (often functions) combined with user interfaces. I'd particularly love help getting this system to a genuinely user-friendly state and perhaps connect it with Pajama's code generator, to produce web content. If you're interested/curious in Pan or Pajama or other collaborations, please email me and/or grab me next week at HW or ICFP. Questions & comments also welcome. Cheers, - Conal

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ANN: Haskell98 termination analyzer (AProVE)
by Stephan Swiderski 11 Sep '06

11 Sep '06

Dear all, we are pleased to announce the integration of an automatic Haskell98 termination analyzer in the termination tool AProVE [1]. Our tool accepts full Haskell as specified in the Haskell 98 Report and is available through our web interface [2]. USE Our tool checks termination of given start terms w.r.t. a Haskell program. A start term is a Haskell term accepted by the command line of Haskell interpreters like GHCi or Hugs. Moreover, start terms may contain free variables representing arbitrary terminating terms. EXAMPLE For example the start term "take x (repeat y)" can be proved terminating (where "take" and "repeat" are defined in the Haskell prelude). On the other hand, the start term "repeat y" does not terminate, because the function "repeat" generates the infinite list of "y"s. For more details on our approach see [3]. EXPERIMENTS We evaluated our tool on standard libraries (Prelude, List, ...) of the Hugs implementation. In this setting we could show the termination of almost 80 percent of 1281 start terms resulting from these libraries. More details on the evaluation can be found in [4]. FEEDBACK We would be grateful for comments and suggestions on our tool or on our approach. Please send them to: aprove(a)i2.informatik.rwth-aachen.de Stephan Swiderski, Jürgen Giesl, Peter Schneider-Kamp, René Thiemann [1] AProVE home page: http://aprove.informatik.rwth-aachen.de [2] web interface: http://aprove.informatik.rwth-aachen.de/index.asp?subform=termination_proof… [3] RTA06 paper: http://aprove.informatik.rwth-aachen.de/eval/Haskell/RTA06-distribute.ps [4] experimental evaluation: http://aprove.informatik.rwth-aachen.de/eval/Haskell/

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parallel programming support
by Niall Dalton 11 Sep '06

11 Sep '06

Hi, Its been a long time since I attempted cluster programming with Haskell. Browsing around the older and research projects suggests that they are not currently usable with recent GHC (6.5+) - be that gph or existing mpi bindings. Is anyone actively using Haskell for cluster programming and could recommend any particular set of tools? GHC's smp support within a node and binding to mpi between nodes seems the most practical way forward. Thanks, niall

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putStr is not evaluated in the correct order
by Andreas S 10 Sep '06

10 Sep '06

Hello, i've got a newbie question to ask. I'd like to ask for user input in the same line as the prompt. I found this example on the web main = do putStr "Who are you? " name <- getLine putStrLn ("Hello, " ++ name) This works find in ghci, but the compiled code (ghc 6.4.2) executes getLine first before executing putStr. Instead of: Who are you? myself Hello, myself I got: myself Who are you? Hello, myself I'm new with haskell, so I can't be too sure about this, but it seems from putStr implementation in Prelude, putStr should be executed first. Why are they different? And if they are suppose to be different, then how to put prompt and input on the same line for the compiled code? Thank you in advance -andre

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Proposal: unification of style of function/data/type/class definitions
by Bulat Ziganshin 10 Sep '06

10 Sep '06

Hello haskell, we can consider functions as value-to-value mappings, 'type' definitions as type-to-type mappings, 'data' and 'class' as type-to-value mappings but their syntax are different. functions has the most convenient syntax: f patterns_for_parameters | guards = result we can improve readability of various declarations by using the same scheme: class Monad m | Functor m, Monoid m where ... instance Monad (WriterT m) | Monad m where ... data EncodedStream m h | Monad m, Stream m h = ... sequence :: [m a] -> m [a] | Monad m By moving "guards" to the right side we will get more readable definitions where most important information (type/class name and shape of parameters) are written first and less important after Even more unification can be applied to GADT-style definitions and definitions of type/data families. The following is a well-known GADT example rewritten in "functional" style: data Expr t = If (Expr Bool) (Expr t) (Expr t) Expr Int = Lit Int Expr Bool | Eq t = Eq (Expr t) (Expr t) And next is the example of type function which selects optimal array representation depending on type of its elements: type Arr Bool = BitVector Arr u | Unboxed u = UArray u Arr (a,b) = (Arr a, Arr b) Arr a = Array a where Unboxed is a class whose instances are unboxable types. We can also allow to use as guards partial type functions, i.e. functions that defined only for subset of type parameters: type SeqElem [a] = a SeqElem (Sequence a) = a SeqElem (Array a) = a data Collection c | SeqElem c = Coll c In general, any type-level computation can use: * in patterns - any type constructors declared in 'data' statements and their saturated synonyms * in guards - classes (and partial type functions) * at the right side - any type constructors and type functions declared with data/type statements, including associated types/type synonyms Please note that ordinal functions dispatch (via pattern-matching) on the data constructors which appear at the right side of 'data' definitions while type-level computations dispatch (again via pattern-matching) on type constructors which appears on left side of the same 'data' definitions ps: although this idea seems more appropriate for haskell' committee, i propose to use it just now, starting from implementation of different syntax for GADTs -- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com

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How to generate a dll?
by Andreas Marth 09 Sep '06

09 Sep '06

Hallo! I want to make my Haskell program usable from Visual Basic. What is the way to go? (I tried the way the user guide for ghc 6.4.2 describes but the resulting dll was not stable.) While I don't have any clues about language interoperation I guess it is a task that is done many times before. So I would appreciate any pointers. Thanks for any help, Andreas

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H/Direct (HaskellDirect) still maintained?
by Andreas Marth 08 Sep '06

08 Sep '06

Hallo! Does anybody know if H/Direct (also known as HaskellDirect) is still maintained? I tried to get it working but although the homepage states "The sources compiles out of the box with recent versions of GHC, such as ghc-6.2." I could not compile it on windows. Can anyone give me some hints how to get it to compile? Or any other advice? Thanks, Andreas PS: For what I acomplished and where I am stuck: First task is do "make boot" I got MSYS (mingw) so I could do make I got happy so make could use happy I added "C:\ghc\ghc-6.4" and "C:\ghc\ghc-6.4\gcc-lib" to my PATH (in addition to "C:\ghc\ghc-6.4" of course) to let make find perl and gcc I get the error: gcc -c mkNativeInfo.c -o mkNativeInfo.o mkNativeInfo.c:6:19: no include path in which to find stdio.h make [1]: *** [mkNativeInfo.o] Error 1 make: *** Error 1 so I added "C:\ghc\ghc-6.4\include\mingw" where stdio.h is situated but got no further. So here I am stuck. Any hints?

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How do I get a recent cabal for Windows?
by Andreas Marth 08 Sep '06

08 Sep '06

Hallo! I just tried to install cabal-1.1.4 under Windows (Windows 2000 Professional). I downloaded the tar from the cabal page (www.haskell.org/cabal/download.html) unpacked it in a directory did "runghc Setup.lhs configure" (It didn't find haddock, happy, alex and ccphs but didn't complain), did "runghc Setup.lhs build" (It skipped a lot of Distribution.[...] but created dist\build\libHSCabal-1.1.4.a) so I went on and did runghc "Setup.lhs install". And it build "C:\Programme\Cabal\Cabal-1.1.4/HSCabal-1.1.4.o", saved the old package config file and wrote the new one. So everything seemed fine. Unfortunatley I get a ghc crash when I try to use the new Cabal with any Setup.lhs. So does anybody know why and what to do about it? Thanks, Andreas

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xml-rpc in hugs
by David Tolpin 08 Sep '06

08 Sep '06

Hi, I'm trying to use xmlrpc module with hugs. The problems are not really related to this particulare module, so the question is here. A module generated from the DTD for XML-RPC by HaXml contains import in the following form: import Prelude (all, maybe, (++)) or something like that to avoid name conflicts with types of the same name defined in the module. In Hugs it leads to (:) not being imported into the module. Is there a way to import just (:) from the Prelude? Is there a way to import all but some symbols from some module? Is (:) a data constructor? David

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