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ANNOUNCE: secure-sockets version 1.0
by David Anderson 06 Sep '10

06 Sep '10

Hi, I'm happy to announce the first release of secure-sockets, a library which aims to simplify the task of communicating securely between two authenticated peers. -------------------------------------------- -- What it is -------------------------------------------- The API mimicks that of Network.Socket, and introduces the additional notion of peer identity, which is distinct from the endpoint address (host and port). Connections can only be established between two peers who know and expect to be communicating with each other. Transport security is implicitly taken care of: an established Network.Secure.Connection implies that each end of the connection successfully authenticated to the other, and that they have setup strong encryption for your data. -------------------------------------------- -- What it isn't -------------------------------------------- The library leans towards the "zero configuration" end of the spectrum, and basically Just Works. This means that if you know exactly what you want and need for the cipher, authentication algorithm, key type and length, key exchange protocol, HMAC algorithm, rekeying intervals, random number source... Then secure-sockets is not for you. If on the other hand you just want to replace your current cleartext "cipher" and faith-based "authentication" code with something that gives you a good chance of being secure (see caveats in docs), without diving into the rich madness that is full blown SSL, then you might want to take a look. This library assumes that both ends of a connection are using it. The goal of secure-sockets is not to allow you to connect to any SSL-enabled server, or to speak a particular standard flavor of authentication protocol. Internally, secure-sockets uses SSL to achieve its goals, so you might get lucky if you do it just right, but that is an implementation detail. The library is designed to help you easily secure communications between two programs whose implementation you control, not between you and anything out there. -------------------------------------------- -- Links -------------------------------------------- Homepage: http://secure-hs.googlecode.com/ Hackage page: http://hackage.haskell.org/package/secure-sockets Bug tracker: http://code.google.com/p/secure-hs/issues/list Code repository: https://secure-hs.googlecode.com/hg -------------------------------------------- -- Thanks -------------------------------------------- I'd like to thank my employer, Google. Not only did they not get mad at the idea that I might want to hack on Haskell during working hours (as my "20% project"), they also made it very painless for me to open source this code when the time came. -------------------------------------------- -- Questions? -------------------------------------------- Questions, comments, suggestions and patches can be filed in the issue tracker, emailed directly to me, or thrown out on haskell-cafe. Hope you find this code useful! - Dave

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ANNOUNCE: stringsearch 0.3.1, fast searching, splitting and replacing of ByteStrings
by Daniel Fischer 02 Sep '10

02 Sep '10

Changes vs. 0.3.0: - fixed a space leak in the splitting of lazy ByteStrings Changes of the 0.3 series vs. 0.2.*: - improved performance of the searching functions - new functionality: - breaking of ByteStrings at the first occurrence of a substring - splitting a ByteString at each occurrence of a substring - replacing all occurrences of a substring with another string Where bytestring provides the same functionality (Data.ByteString.breakSubstring, Data.ByteString.findSubstrings), the implementations in stringsearch are typically much faster. By default, stringsearch uses an enhanced Boyer-Moore algorithm to locate a pattern, but it also provides other algorithms which may be better in special cases (Knuth-Morris-Pratt; DFA).

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ANN: mute-unmute-0.2.0.0
by Krzysztof Skrzętnicki 01 Sep '10

01 Sep '10

* Hello! I'm pleased to announce a small utility program I wrote recently. Today I pushed version 0.2.0.0 of mute-unmute to Hackage, from with you can cabal-install it right now (following the usual 'update' step). What it does? It's simple: it will mute the sound when you lock your screen and unmute it back again when you unlock it. Why anyone would need such program? Well, this is a little bit more complicated. I work in "open space" kind of office. It can get quite noisy there. I often sit with headphones on, but when I walk away from my desk I put them down and lock my screen. Here comes uncomfortable moment: when I remove my headphones suddenly people around me who doesn't use their headphones now start to hear the music I listen to. And they don't always like it, so I manually mute the sound to make happy. But now, instead of doing this task by hand I have a program do it for me :-) Unfortunately this kind of programs tend to be pretty much platform specific. Current version supports the recent versions of Gnome and KDE, but needs ALSA. It's quite common setup, but if you happen to have a different one you can easily hack the code (it's very straightforward) and send me patches. Patches are always welcome. The source repo is on Github and released versions are on Hackage: Github: http://github.com/Tener/mute-unmute <http://github.com/Tener/mute-unmute#> Hackage: http://hackage.haskell.org/package/mute-unmute Example use: ~/ mute-unmute # first session, it will ask for configuration options mute-unmute: Creating config directory... mute-unmute: Mute config is missing... Mute sound card and press RETURN mute-unmute: Unmute config is missing... Unmute sound card and press RETURN mute-unmute: Session: UnixAbstract {addrPath = "/tmp/dbus-1tB1AEUcgg", addrGuid = Just "19ec85e3778816ad38a77bbf0000003f"} mute-unmute: Connected mute-unmute: Handler added: [MatchType Signal,MatchInterface "org.gnome.ScreenSaver",MatchMember "ActiveChanged",MatchPath "/org/gnome/ScreenSaver"] mute-unmute: Handler added: [MatchType Signal,MatchInterface "org.freedesktop.ScreenSaver",MatchMember "ActiveChanged",MatchPath "/ScreenSaver"] ^C ~/ mute-unmute # remembers previous options which can be changed by calling with --store switch mute-unmute: Session: UnixAbstract {addrPath = "/tmp/dbus-1tB1AEUcgg", addrGuid = Just "19ec85e3778816ad38a77bbf0000003f"} mute-unmute: Connected mute-unmute: Handler added: [MatchType Signal,MatchInterface "org.gnome.ScreenSaver",MatchMember "ActiveChanged",MatchPath "/org/gnome/ScreenSaver"] mute-unmute: Handler added: [MatchType Signal,MatchInterface "org.freedesktop.ScreenSaver",MatchMember "ActiveChanged",MatchPath "/ScreenSaver"] mute-unmute: Message {mType = Signal, mFlags = [NoReplyExpected], mSerial = 31, mPath = Just "/org/gnome/ScreenSaver", mInterface = Just "org.gnome.ScreenSaver", mMember = Just "ActiveChanged", mErrorName = Nothing, mReplySerial = Nothing, mDestination = Nothing, mSender = Just ":1.19", mBody = [Variant (True) {- b -}]} mute-unmute: Lock screen mute-unmute: Message {mType = Signal, mFlags = [NoReplyExpected], mSerial = 32, mPath = Just "/org/gnome/ScreenSaver", mInterface = Just "org.gnome.ScreenSaver", mMember = Just "ActiveChanged", mErrorName = Nothing, mReplySerial = Nothing, mDestination = Nothing, mSender = Just ":1.19", mBody = [Variant (False) {- b -}]} mute-unmute: Unlock screen ^C * You can get usage information with --help switch: *~/ mute-unmute --help *mute-unmute --store ask for mute and unmute configurations --store-mute ask for mute configuration --store-unmute ask for unmute configuration -d --daemon wait for screensaver state changes -h, -? --help show help There isn't much more I can say. I hope you find the program at least educational (as a simple example of DBus usage) if not useful. Best regards, Krzysztof Skrzętnicki

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ANN: Hayoo! 2.1
by "Timo B. Hübel" 01 Sep '10

01 Sep '10

Hi, We are pleased to announce the next major release 2.1 of Hayoo!, the Haskell API search engine with find-as-you-type and suggestions. Visit Hayoo! here: http://holumbus.fh-wedel.de/hayoo What's new? Thanks to Uwe Schmidt, we have completely revamped the indexer, which now also crawls package information from Hackage. Hence, Hayoo! now searches package names, package categories, package descriptions etc., too, and shows you some package results along with the functions found (some of you may have noticed this already, since this is live for testing purposes since a few months). For example, this will find you all packages in the category "Algorithms" that will do something with "sat": category:algorithms sat This will find you some strict datastructures (i.e. synopsis contains "strict" and category contains "data"): synopsis:strict category:data As we now have package information present in the search index, the algorithm for ranking the results has been adjusted to mainly depend on reverse package dependencies. Nevertheless, we are still trying to optimize this. The new indexer also supports incremental index updates, which made a rebuild of the whole infrastructure around it possible. This way, we are now able to provide daily index updates. Useful figures about the current index are shown below the query input field. Additionally, we have made some optimizations and performance improvements. This allowed us to leverage the restrictions on the query length and hence it is now possible to search for any single character (try searching for "s"). In the result display, the whole function description is now included and its formatting is preserved. Internally, the HTML rendering part has been completely rewritten, which hopefully allows for faster adoption of new features. Please let us know about any issues or suggestions. Especially some opinions about how to integrate the package information in the result display would be appreciated. Thanks, Timo

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Three new implementations of multi-prompt delimited control
by oleg＠okmij.org 01 Sep '10

01 Sep '10

The monadic framework for delimited continuations described in the paper by Dybvig, Peyton Jones and Sabry (JFP 2007) has found many applications, for example, fair backtracking search, final zippers, direct-style web programming, direct-style code generation, and probabilistic programming. The extensive experience suggested improvements in efficiency and, mainly, programmer's convenience. The three new libraries are novel implementations of the enhanced framework. Prompts, for instance, can now be bound to top-level identifiers and do not have to be passed around explicitly or through the extra Reader monad. The new libraries benefited from the experience of implementing delimited control on several platforms. All three libraries provide monad transformers, with basic operations to capture and reinstall delimited continuations: pushPrompt, shift, shift0, control, takeSubCont/pushSubCont. All three libraries support multiple, typed prompts. All three libraries are quite distinct from the original implementation in Dybvig, Peyton Jones, Sabry's paper. For instance, none of the new libraries use unsafeCoerce. All three implementations are derived from the specification of delimited control: from the reduction semantics or from the definitional interpreter. The new libraries differ in -- performance -- ease of understanding -- constraints on the base monad or the prompt types -- flavors of prompts and support for global prompts The libraries are named CCRef, CCExc and CCCxe. The complete code of the libraries along with the regression test suite are publicly available at http://okmij.org/ftp/continuations/CCmonad/ The directory includes sample code (Generator1.hs and Generator2.hs), implementing generators like those of Python. A more extensive example is the porting of the LogicT library (of fair backtracking monad transformers), from the old CC implementation to CCExc/CCCxe: http://okmij.org/ftp/Haskell/LogicT.tar.gz One of the sample applications of LogicT, of a computer playing 5x5 tic-tac-toe against itself, was used as a macro-benchmark of the libraries. The end of the file TicTacToe.hs summarizes the results. The new libraries are faster (so the reader who may wish to play will have less time to think). The library CCRef is closest to the interface of Dybvig, Peyton Jones and Sabry. CCRef is derived from the definitional interpreter using the implementation techniques described and justified in the FLOPS 2010 paper. The monad transformer CC implemented by CCRef requires the base monad to support reference cells. In other words, the base monad must be a member of the type class Mutable: that is, must be IO, ST, STM or their transformer. CCRef adds to the original interface the frequently used function abortP as a primitive. As one may notice from their names, the libraries CCExc and CCCxe are closely related. CCCxe is derived as a CPS version of CCExc. CCCxe is sometimes more efficient; it is always less perspicuous. Both libraries provide the identical interface and are interchangeable. It seems that CCExc is faster at delimited control but imposes more overhead on the conventional code; CCCxe is dual. It pays to use CCCxe in code with long stretches of determinism punctuated by fits and restarts. We now explain new features of CCExc. It is the most direct implementation of the bubble-up (bottom-up) reduction semantics of multi-prompt delimited control, described on PDF page 57 of http://okmij.org/ftp/gengo/CAG-talk.pdf Unlike all other implementations of delimited control in Haskell, CCExc is _not_ based on the continuation monad. Rather, the monad of CCExc is an extension of the Error monad: a monad for restartable exceptions. CCExc offers not one monad transformer but a family (CC p), parameterized by the prompt flavor p. The library defines several prompt flavors; the users are welcome to define their own. Prompt flavors are inherently like exception flavors (the FLOPS 2010 paper even calls prompts `exception types' or `exception envelopes'). Control.Exception defines singular global exceptions such as BlockedOnDeadMVar. There are global exceptions like ErrorCall, parameterized by the error string. There are closed global variants, such as ArithException, with the fixed number of alternatives. There are also open variants, SomeException, with any number of potential alternatives. Users may define their own exception types, whose visibility may be restricted to a module or a package. Finally, one may even generate distinct expression types dynamically, although that is seldom needed. The libraries CCExc and CCCxe support all these flavors. On one end is the prompt flavor (PS w). There is only one prompt of that flavor, which is globally defined and does not have to be passed around. The monad transformer (CC (PS w)) then is the monad transformer for regular, single-prompt delimited continuations, for the answer-type w. Danvy/Filinski test, which looks in Scheme as > (display (+ 10 (reset (+ 2 (shift k (+ 100 (k (k 3)))))))) appears as follows in Haskell: > test5 = (print =<<) . runCC $ > incr 10 . pushPrompt ps $ > incr 2 . shiftP ps $ \sk -> incr 100 $ sk =<< (sk 3) where > incr :: Monad m => Int -> m Int -> m Int > incr n = ((return . (n +)) =<<) [A reader might wish to try to predict the result of test5.] The global identifier ps is defined in CCExc. One should read the operator (=<<), the flipped bind, as a ``call-by-value application'', akin to the application in CBV languages such as Scheme. That is, "f =<< e" is the application that first evaluates the argument e, performing its effects. The value is passed to f, which is evaluated in turn. The application "sk 3" is an optimized version of "sk =<< (return 3)". The appearance of print tells us that test5 is the IO computation. If we rather had the result of test5 as a pure value (an integer), we merely need to pass the result of the runCC expression to runST. The file Generator1.hs shows one example of using PS; the file SRReifT.hs of the LogicT is a larger example. The file Generator2.hs demonstrates why we may need more than one prompt (perhaps with different types). The library offers several flavors of multiple prompts: closed unions (P2) and open unions (PP, PM, PD). The open unions are like SomeException. The prompt flavor PD carries an extra integer identifier to further distinguish prompts of the same type. It becomes possible therefore to dynamically generate an arbitrary number of PD prompts, which was required in Dybvig, Peyton Jones and Sabry's framework. We close by juxtaposing the Python code that uses generators to traverse a binary tree in-order >>> def inorder(t): ... if t: ... for x in inorder(t.left): ... yield x ... yield t.label ... for x in inorder(t.right): ... yield x with the corresponding Haskell code (excerpted from Generator1.hs) > in_order :: (Monad m) => Tree -> CC (P m Label) m () > in_order Leaf = return () > in_order (Node label left right) = do > in_order left > yield label > in_order right In Python, 'yield' is a keyword and generators are built-in. In Haskell, yield is a regular, small, user-defined function, and generators are programmed-in.

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ANNOUNCE: iteratee-compress 0.1
by Maciej Piechotka 31 Aug '10

31 Aug '10

Iteratee-compress provides compressing and decompressing enumerators. Currently only gzip is provided but at least bzip is planned. Additionally more fine-control over stream (i.e. flushing) is planned. ---- Library currently depends on zlib haskell library only for sharing parameters data. However no zlib function is called (the needed functions are not exported) and the symbols it uses from necessity are deprecated. Would it be better to copy the parameters from zlib and drop the dependency? Please note also that the library do not bundle zlib (C) as zlib (Haskell) do.

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ANNOUNCE: Industrial Haskell Group round 2
by Ian Lynagh 31 Aug '10

31 Aug '10

Hi all, The Industrial Haskell Group is now in the process of beginning the second round of the collaborative development scheme. If your company is interested in becoming a member of the IHG, please get in contact with us during the next month at info(a)industry.haskell.org To get an idea of what the IHG does and how it works, please see the website: http://industry.haskell.org/status and feel free to drop us an e-mail if you have any questions. -- Ian Lynagh, Haskell Consultant Well-Typed LLP, http://www.well-typed.com/

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HLPP 2010 Call for participation
by Frederic Loulergue 28 Aug '10

28 Aug '10

Fourth International Workshop on High-level Parallel Programming and Applications (HLPP 2010) Baltimore, Maryland, September 25, 2010 Affiliated to ICFP 2010 http://www.icfpconference.org/icfp2010 Sponsored by ACM SIGPLAN Aims and Scope As processor and system manufacturers adjust their roadmaps towards increasing levels of both inter and intra-chip parallelism, so the urgency of reorienting the mainstream software industry towards these architectures grows. At present, popular parallel and distributed programming methodologies are dominated by low-level techniques such as send/receive message passing, or equivalently unstructured shared memory mechanisms. Higher-level, structured approaches offer many possible advantages and have a key role to play in the scalable exploitation of ubiquitous parallelism. This workshop provides a forum for discussion and research about such high-level approaches to parallel programming. Workshop Program 08:00-08:45: Continental Breakfast 09:00-10:00: Invited Talk Zhenjiang Hu (National Institute of Informatics) Calculational Parallel Programming 10:00-10:30: Break 10:30-12:00: Session "Skeletal Parallelism" Johan Enmyren and Christoph Kessler SkePU: A Multi-Backend Skeleton Programming Library for Multi-GPU Systems Kiminori Matsuzaki and Kento Emoto Lessons from Implementing the BiCGStab Method with SkeTo Library Oleg Lobachev and Rita Loogen Estimating Parallel Performance, A Skeleton-Based Approach 12:00-12:30: Session "Verification of High-Level Parallel Programs" Frédéric Gava and Jean Fortin BSP-Why: an intermediate language for deductive verification of BSP programs 12:30-02:00: Lunch 02:00-03:00: Invited Talk Phil Trinder (Heriot-Watt University) SymGrid-Par: A Standard Skeleton-Based Framework for Computational Algebra Systems 03:00-03:30: Break 03:30-04:30: Session "Bulk Synchronous Parallelism" Md. Mostofa Ali Patwary, Rob H. Bisseling and Fredrik Manne Parallel Greedy Graph Matching using an Edge Partitioning Approach Joel Falcou, Khaled Hammidouche and Daniel Etiemble Hybrid Bulk Synchronous Parallelism Library for Clustered SMP Architectures 04:30-05:00: Break Programme Committee Anne Benoit (ENS Lyon, France) Murray Cole (University of Edinburgh, UK) Alexandros Gerbessiotis (New Jersey Institute of Technology, USA) Christoph Kessler (Linköpings Universitet, Sweden) Herbert Kuchen (University of Muenster, Germany) Rita Loogen (University of Marburg, Germany) Frédéric Loulergue (University of Orléans, France), chair Kiminori Matsuzaki (Kochi University of Technology, Japan) Samuel Midkiff (Purdue University, USA) Susanna Pelagatti (University of Pisa, Italy) Sukyoung Ryu (Korea Advanced Institute of Science and Technology, Korea) Kazunori Ueda (Waseda University, Japan) ----- Fin du message transféré -----

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ANNOUNCE: ListLike-1.0.2
by John Lato 27 Aug '10

27 Aug '10

Hello, I am pleased to announce that, with the permission of John Goerzon, I will be maintaining the ListLike package. John Goerzon has made many significant contributions to Haskell projects and the community, and I hope that I will be able to keep this package available to the high standard of his work. John Lato

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MSFP - early registration: 30 August
by Venanzio Capretta 27 Aug '10

27 Aug '10

Early registration for MSFP closes on 30 August. To register, please use the ICFP registration page: https://regmaster3.com/2010conf/ICFP10/register.php Third Workshop on MATHEMATICALLY STRUCTURED FUNCTIONAL PROGRAMMING 25 September 2010, Baltimore, Maryland, USA A satellite workshop of ICFP 2010 PRESENTATION The workshop on Mathematically Structured Functional Programming is devoted to the derivation of functionality from structure. It is a celebration of the direct impact of Theoretical Computer Science on programs as we write them today. Modern programming languages, and in particular functional languages, support the direct expression of mathematical structures, equipping programmers with tools of remarkable power and abstraction. Monadic programming in Haskell is the paradigmatic example, but there are many more mathematical insights manifest in programs and in programming language design: Freyd-categories in reactive programming, symbolic differentiation yielding context structures, and comonadic presentations of dataflow, to name but three. This workshop is a forum for researchers who seek to reflect mathematical phenomena in data and control. The first MSFP workshop was held in Kuressaare, Estonia, in July 2006. Selected papers were published as a special issue of the Journal of Functional Programming (volume 19, issue 3-4). The second MSFP workshop was held in Reykjavik, Iceland as part of ICALP 2008. PROGRAM 9:00 - 10:00 Invited talk: Amy Felty, "Hybrid: Reasoning with Higher-Order Abstract Syntax in Coq and Isabelle" 10:00 - 10:30 break 10:30 - 11:00 Chantal Keller and Thorsten Altenkirch, "Normalization by hereditary substitutions" 11:00 - 11:30 Paul Tarau, "Hereditarily finite representations of natural numbers and self delimiting codes" 11:30 - 12:30 Tutorial: Adam Chlipala, "Foundational Program Verification in Coq with Automated Proofs" 12:30 - 2:00 lunch break 2:00 - 3:00 Invited talk: Martín Escardó, "What Tic-Tac-Toe, the Tychonoff Theorem, and the Double-Negation Shift have in common" 3:00 - 3:30 break 3:30 - 4:00 Kazuyuki Asada, "Arrows are Strong Monads" 4:00 - 4:30 Adam Gundry, Conor McBride and James McKinna, "Type inference in context" 4:30 - 5:00 break 5:00 - 6:00 Tutorial: Peter Morris, "Epigram Prime: A Demonstration" Workshop homepage: http://cs.ioc.ee/msfp/msfp2010/ Registration link: https://regmaster3.com/2010conf/ICFP10/register.php Local arrangements: http://www.icfpconference.org/icfp2010/local.html

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