November 2009 - Haskell

ANN: fdo-notify 0.1, a client for the Desktop Notifications protocol
by Max Rabkin 04 Nov '09

04 Nov '09

Haskellers, I present to you fdo-notify, a client library for FreeDesktop.org's Desktop Notifications protocol. This is the DBUS protocol served by NotifyOSD and other notifications systems, which allows a wide variety of applications to present notifications to the user in a uniform way. The library should not require knowledge of DBus or the Desktop Notifications protocol itself, at least once fully documented (there should be enough haddocumentation for basic use already). Hackage: http://hackage.haskell.org/package/fdo-notify Mercurial: http://bitbucket.org/taejo/fdo-notify/ Basic notifications and updated/replacement notifications are supported. Images are not yet supported (adding support should be easy, but which Image type? Is there a de facto standard imaging library like the Python Imaging Library?) and nor are signals. Signals allow an application to be informed when some action is taken on the notification (NotifyOSD doesn't support actions, but other implementations might). The library is released under the 3-clause BSD license, but depends on the dbus-core and dbus-client libraries which are GPLed. I hope you find this library useful. Regards, Max

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ANN: haskell-src-exts-1.3.0
by Niklas Broberg 04 Nov '09

04 Nov '09

Fellow Haskelleers, I'm pleased to announce the release of haskell-src-exts-1.3.0! * On hackage: http://hackage.haskell.org/package/haskell-src-exts * Via cabal: cabal install haskell-src-exts * Darcs repo: http://code.haskell.org/haskell-src-exts Version 1.3.0 is a new major release, following the PVP, as it contains a few backwards-incompatible changes, making the 1.2.x branch a very short parenthesis in history. There are two main new things in 1.3.0: fixity application is now handled uniformly regardless of which AST you use, simple or annotated, and the parser now supports multiple modules in the same source file. haskell-src-exts-1.3.0: ==================== * The *.Fixity modules now export the same Fixity type (incidentally the one previously used by the simple un-annotated parsing) and the same helper functions. If you've done all your Fixity handling using the helper functions (infix_, infixl_, infixr_), or if you've only used fixities for the un-annotated AST, you're safe. Only if you've manually created values of the annotated Fixity type will you need to pay attention. * A new entry point in the parser allows multiple modules to be parsed from the same source file ( parseModules[With[Mode|Comments]] ). * SpecialCon is now an instance of Pretty (don't ask me why it wasn't before). * fromParseResult now displays the filename in case of a failed parse. * A few bug fixes to the exact-printer (that not many seem to be using just yet). Please help me test and report! Grab a darcs version, put your source files in the Test/examples dir, and go cabal test (in the top dir). Any failing cases not due to CPP or literate source files (for the exact-printer), please report to the trac: http://trac.haskell.org/haskell-src-exts Cheers, /Niklas

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ANNOUNCE: feldspar-language
by Emil Axelsson 04 Nov '09

04 Nov '09

I'm happy to announce the first release of Feldspar, which is an embedded domain-specific language with associated code generator mainly targeting DSP algorithms. The language is developed in cooperation by Ericsson, Chalmers University and Eötvös Loránd University. Feldspar stands for *F*unctional *E*mbedded *L*anguage for *DSP* and *PAR*allelism. The language front-end is available on Hackage: http://hackage.haskell.org/package/feldspar-language The back-end C code generator will be uploaded and announced shortly. For more information, see: http://feldspar.sourceforge.net/ / Emil

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about verification of haskell program
by Liu Jian 03 Nov '09

03 Nov '09

Dear all, Is there any work about "model checking haskell program"? In my opinion, think the haskell as a specification language, then we can check it or transform it to other specification language (such as, promela), so can be analyzed. cheers, Liu Jian ---- email to: gjk.liu(a)gmail.com

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ANNOUNCE: control-monad-exception 0.5 with monadic call traces
by Jose Iborra 02 Nov '09

02 Nov '09

Folks, I'm happy to announce a new release of control-monad-exception with monadic call traces, available in Hackage. Grab it now while it is still online! Monadic stack traces are described in detail in a blog post [1]. In short, what this means for your code is the ability to generate errors like this: 500 Internal Server Error The CGI server failed with the following error: DeleteException (BmPK 2009-10-26 19:39:51.031297 UTC "Testing RPO") in deleteBenchmarkFromPK, NarradarBenchmarkDB(src/ NarradarBenchmarkDB.hs): (186, 44) deleteBenchmarkFromPK, NarradarBenchmarkDB(src/ NarradarBenchmarkDB.hs): (186, 25) deleteBenchmarkFromPK, NarradarBenchmarkDB(src/ NarradarBenchmarkDB.hs): (184, 17) deleteBenchmarkFromPK, NarradarBenchmarkDB(src/ NarradarBenchmarkDB.hs): (180, 90) deleteTests, NarradarBenchmarkCGI(src/NarradarBenchmarkCGI.hs): (108, 3) deleteTests, NarradarBenchmarkCGI(src/NarradarBenchmarkCGI.hs): (106, 20) cgiMain, NarradarBenchmarkCGI(src/NarradarBenchmarkCGI.hs): (52, 33) cgiMain, NarradarBenchmarkCGI(src/NarradarBenchmarkCGI.hs): (52, 30) cgiMain, NarradarBenchmarkCGI(src/NarradarBenchmarkCGI.hs): (50, 9) cgiMain, NarradarBenchmarkCGI(src/NarradarBenchmarkCGI.hs): (46, 11) Currently a preprocessor is used to insert the source location information in the right places. The preprocessor is invoked by including the following pragma at the top of your Haskell source files: {-# OPTIONS_GHC -F -pgmF MonadLoc #-} In addition, you need to be in a monad which implements the Monadloc interface, currently the EMT monad from control-monad-exception being the only one, although it is trivial to enhance any error monad to implement this interface. In addition, support for monadic stack traces could be built into GHC and: 1. No preprocessor would be needed. 2. Eventually the IO monad could be enhanced to provide stack traces like this. Enjoy your monadic call traces ! Pepe Iborra [1] - http://pepeiborra.posterous.com/monadic-stack-traces-that-make-a-lot-of-sen…

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two PhD positions in static analysis, Technical University Munich, Germany
by Axel Simon 02 Nov '09

02 Nov '09

Dear all, The chair II for computer science at the Technical University Munich is offering two PhD positions in the area of program analysis. The first position ("low-level analysis") is centered around defining an implementing an analysis of x86 assembler code and, in particular, of concurrency constructs. The second position ("high-level analysis") is geared towards the analysis of data structures (aka shape analysis) using numeric invariants. The intention is to extend an existing analyzer that performs a forward-reachability analysis with the aim to prove the absence of memory management errors and other defects in legacy C software. This analyzer is written in Haskell. first position: low-level analysis ---------------------------------- Most program analysis tools operate on the source code, usually C, since information on variable types, data structures and basic blocks is not available in the executable. One problem with this approach is the definition of the exact semantics of C source code as many constructs commonly found in hand-written programs are ``implementation-dependent'' or even ``undefined'' according to the C standard. These uncertainties are exacerbated when analyzing programs that make use of concurrency constructs. The goal is therefore to directly analyze the resulting x86 machine code and to reconstruct the control flow graph and data structures on-the-fly. The analysis of concurrent programs moreover requires that (abstract) states are propagated between different threads. The challenge here lies in storing a minimum number of abstract states (to reduce the memory requirements) and to get away with a minimum amount of propagation between threads. ------------------------------------- second position: high-level analysis ----------------------------------- One recurring challenge in analysing programs is the precise summarization of data structures. This so-called shape analysis commonly uses logic formulae (e.g. separation logic) to describe a data structure contained in a memory region. In this approach, a predicate must be present that describes the invariant (e.g. "list(p)" might mean that p points to a memory region containing a singly-linked list). If no predicate is available that matches the data structure that is being built by a program, the logic formula must be discarded in order to ensure termination, thereby discarding both, the shape of a memory region and the information on how it is connected to other memory regions. The goal of this position is to find novel abstractions that infer the shape of a memory region and its connection to other memory regions separately. The connection to other memory regions are then annotated with numeric variables that denote how many memory regions are reachable via the connection. The values of these variables is then tracked separately, allowing a more graceful loss of precision. am only the numeric information needs to be relaxed since number of different shapes is fixed by the structure of the program. ------------------------------------- Both positions are fully funded for 4 years and do not come with any teaching duties. The PhD students may start as soon as January 1, 2010. The salary is TVL E13 (about 2900 EUR/1650 EUR per month). The positions are part of the Emmy Noether Programme "Verifying Legacy C Programs using Numeric Domains" which is headed by Axel Simon. This project, in turn, is located within the chair of Helmut Seidl. The PhD students will be supervised by Axel Simon. What you should provide: - Master (or equivalent) degree in Computer Science or Maths - good programming skills - an interest in compiler construction, program optimization and the like - not afraid of discrete maths, lattices etc. - good writing skills in English and Haskell - an electronic application including detailed CV by December 1 (later applications may not be considered) Contact: Please send applications and any enquiries to: Axel.Simon(a)ens.fr

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