April 2006 - Haskell - Haskell.org

Announcing Djinn, version 2004-12-11, a coding wizard
by Lennart Augustsson 07 Apr '11

07 Apr '11

Howdy, y'all! I've written a small program that takes a (Haskell) type and gives you back a function of that type if one exists. It's kind of fun, so I thought I'd share it. It's probably best explained with a sample session. calvin% djinn Welcome to Djinn version 2005-12-11. Type :h to get help. # Djinn is interactive if not given any arguments. # Let's see if it can find the identity function. Djinn> f ? a->a f :: a -> a f x1 = x1 # Yes, that was easy. Let's try some tuple munging. Djinn> sel ? ((a,b),(c,d)) -> (b,c) sel :: ((a, b), (c, d)) -> (b, c) sel ((_, v5), (v6, _)) = (v5, v6) # We can ask for the impossible, but then we get what we # deserve. Djinn> cast ? a->b -- cast cannot be realized. # OK, let's be bold and try some functions that are tricky to write: # return, bind, and callCC in the continuation monad Djinn> type C a = (a -> r) -> r Djinn> returnC ? a -> C a returnC :: a -> C a returnC x1 x2 = x2 x1 Djinn> bindC ? C a -> (a -> C b) -> C b bindC :: C a -> (a -> C b) -> C b bindC x1 x2 x3 = x1 (\ c15 -> x2 c15 (\ c17 -> x3 c17)) Djinn> callCC ? ((a -> C b) -> C a) -> C a callCC :: ((a -> C b) -> C a) -> C a callCC x1 x2 = x1 (\ c15 _ -> x2 c15) (\ c11 -> x2 c11) # Well, poor Djinn has a sweaty brow after deducing the code # for callCC so we had better quit. Djinn> :q Bye. To play with Djinn do a darcs get http://darcs.augustsson.net/Darcs/Djinn or get http://darcs.augustsson.net/Darcs/Djinn/Djinn.tar.gz Then just type make. (You need a Haskell 98 implementation and some libraries.) And then start djinn. For the curious, Djinn uses a decision procedure for intuitionistic propositional calculus due to Roy Dyckhoff. It's a variation of Gentzen's LJ system. This means that (in theory) Djinn will always find a function if one exists, and if one doesn't exist Djinn will terminate telling you so. This is the very first version, so expect bugs. :) Share and enjoy. -- Lennart

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Haskell-mode 2.0
by Stefan Monnier 02 Feb '09

02 Feb '09

I have recently taken over maintainership of Haskell-mode, and after making a bunch of changes, I figured it would be a good idea to make a new release. You can find this new release at: http://www-perso.iro.umontreal.ca/~monnier/elisp/ If you think it should also be found at http://www.haskell.org/haskell-mode/, then please tell John Peterson to get back to me (my email to him seem to go straight to the bitbucket. John?). This release has several changes that have all been only lightly tested, especially w.r.t compatibility with various Emacsen. See appended the NEWS file that describes some of the notewirthy changes. Stefan Changes since 1.45: * keybindings C-c <char> have been replaced by C-c C-<char> so as not to collide with minor modes. * The following modules are now automatically activated without having to add anything to haskell-mode-hook: haskell-font-lock (just turn on global-font-lock-mode). haskell-decl-scan (just bind `imenu' to some key). * In recent Emacsen, haskell-doc hooks into eldoc-mode. * haskell-hugs and haskell-ghci are superceded by inf-haskell. * Indentation rules have been improved when using layout inside parens/braces. * Symbols like -> and \ can be displayed as actual arrows and lambdas. See haskell-font-lock-symbols. * Tweaks to the font-lock settings. Among other things paren-matching with things like \(x,y) should work correctly now. * New maintainer <monnier(a)gnu.org>.

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Compilation of big, computed tables
by Stefan Karrmann 24 Oct '06

24 Oct '06

Dear all, can ghc compile huge tables into efficient code if they are constant at compile time? Two examples may clearify the question: big1 :: UArray Int Char big1 = array (0,1000) $! map (\i -> (i,toEnum i)) [0..1000] big2 = sum [0..10000]::Int -- == 50005000 == n*(n+1)/2 where n = 10000 Both values are constant at compile time. As they are given by pure functions, the compiler could evaluate them and write the *result* into the object file 'foo.o'. This would save code size and run time. I peeked into 'foo.hc' but I didn't found 0x2fb0408 nor an array {0, 1, 2, 3, ..., 1000} or similar things. The function in big2 should show that the computation of the value could be very time consuming. If the compiler does not compute it, the source file could be generated by a helper program (or template Haskell?). The function in big1 should show that the conversion of the data into an array could be run-time, code-size and heap-size consuming. (You need the list (maybe explicitly - think of 1000 fixed pseudo-random numbers) and convert it into an array.) If the compiler generates the unboxed array directly it could be rather efficient. PS: I compiled with: ghc6 -c -O2 -keep-tmp-files -keep-hc-files foo.hs Regards, -- Stefan Karrmann

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"strange" behavior of Implicit Parameters
by Eike Scholz 08 Aug '06

08 Aug '06

Hi, I have just a short question, about the semantics of Implicit parameters on GHC 6.4. Given the following code: > (???) x f > = let ?foo = 1337 > in f x > fun :: (?foo::Int,Show x) => x -> String > fun x = "x = "++(show x)++"; ?foo = "++(show ?foo) > test = let ?foo = 23 > in 42 ??? fun I would expect: test == "x = 42; ?foo = 1337" Because I thought, that it gets reduced like: let ?foo = 23 in 42 ??? fun ~> let ?foo = 23 in (let ?foo = 1337 in fun 42) ~> ... ~> "x = 42; ?foo = 1337" however I get "x = 42; ?foo = 23" in ghci. Is there a special reason, why the implicit parameter is reduced first? Could it be a bug? Reducing it my way would be very useful for combinator-libraries, since it could be used passing around state info, or simple debug text, that tells where a Runtime-error occured? an odd example: > undef = error ?errstr > (<?>) x s = let ?errstr = ?errstr++"\n"++s in x -- annotate error tags so error annotations will accumulate and it would be easy to resolve runtime errors. best regards Eike Scholz

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Non-exhaustive pattern in Socket.hsc
by Dominic Steinitz 29 Apr '06

29 Apr '06

I'm getting [root@tility pcap]# ./test test: Socket.hsc:(1434,17)-(1523,20): Non-exhaustive patterns in case The problem is caused because pcap_findalldevs is returning an address family value of 17 #define PF_PACKET 17 /* Packet family. */ #define AF_PACKET PF_PACKET and the ghc Family datatype doesn't support it :-( data Family = AF_UNSPEC | AF_UNIX | AF_INET | AF_INET6 | AF_SNA | AF_DECnet | AF_APPLETALK | AF_ROUTE | AF_X25 | AF_AX25 | AF_IPX -- Imported from Network.Socket *Main> map packFamily [AF_UNSPEC,AF_UNIX,AF_INET,AF_INET6,AF_SNA,AF_DECnet,AF_APPLETALK,AF_ROUTE,AF_X25,AF_AX25,AF_IPX] [0,1,2,10,22,12,5,16,9,3,4] I think I have two choices: 1. Amend ghc. I haven't built ghc for a long time. Would I have to build the whole of ghc? I presume I would have to because of dependencies. 2. Use Network.Alt since http://www.cs.helsinki.fi/u/ekarttun/network-alt/doc/Network.Alt.Types.html defines type Family = Int Any advice? What is the long term plan for Network anyway? Thanks, Dominic.

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FW: TV06 (Threads Verification) Workshop - New Deadlines, Student Bursaries, ...
by Simon Marlow 28 Apr '06

28 Apr '06

Posting on behalf of Ganesh [ganesh(a)cs.utah.edu] INTERNATIONAL WORKSHOP on MULTITHREADING in HARDWARE and SOFTWARE (TV06) Sponsored by Microsoft (bursaries for 6 student papers - see URL) August 21-22, 2006, Seattle, WA (after CAV 2006; part of FLoC 2006) NEW DEADLINES: Submissions: May 15; Acceptance: June 20; Final version: July 20 INVITED SPEAKERS: Maurice Herlihy (Brown), Vijay Saraswat (IBM T.J. Watson Res. Ctr.), Nir Shavit (Sun) URL : http://www.cs.utah.edu/tv06/ (info on submissions, bursaries) TOPICS: * Analysis, testing, and verification techniques for concurrent systems * Experience building reliable and high-performance multithreaded systems * Verification case studies and experience reports * Language design and formal semantics pertaining to threading * Logics and models of concurrency, including transaction memories * Model checking (dealing with library calls, weak consistency models, etc.) * Shared memory consistency models (language, hardware, library levels) * Runtime verification for multithreaded programs and systems * Threading based solutions (hardware/software) in multi-core systems and chips * Designing formally well-specified high-performance thread libraries * Understanding threading issues in specific areas such as high-performance computing (e.g., OpenMP), general purpose libraries (e.g., PThreads), and languages (e.g., C#, Java) PROGRAM COMMITTEE: Arvind, MIT CSAIL Hans Boehm, HP Ching Tsun Chou, Intel Byron Cook, Microsoft Research Cambridge Robert P. Cook, Georgia Southern University Cormac Flanagan, UC Santa Cruz Robert M. Kirby, University of Utah Timothy G. Mattson, Intel Shaz Qadeer, Microsoft Research John Regehr, University of Utah Scott Stoller, SUNY at Stony Brook Yue Yang, Microsoft CONTACT INFO: http://www.cs.utah.edu/tv06/ -- tv06(a)cs.utah.edu ORGANIZERS: Ganesh Gopalakrishnan (Univ of Utah) and John O'Leary (Intel) --

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(2nd CFP) Workshop on Logic-based Methods in Programming Environments
by Wim Vanhoof 27 Apr '06

27 Apr '06

[Apologies for multiple postings] ----------------------------------------------------------- WLPE' 06 - 2nd CALL FOR PAPERS Workshop on Logic-based Methods in Programming Environments (satellite workshop of ICLP’06) August 16, 2006 Seattle (Washington), USA http://lml.ls.fi.upm.es/~susana/Conferences/WLPE06/ ----------------------------------------------------------- Aim and Scope ------------- The 16th Workshop on Logic-based methods in Programming Environments will take place in Seattle (Washington), USA, as a satellite workshop of ICLP'06, the 22th International Conference on Logic Programming. This workshop will continue the series of successful international workshops on logic programming environments held in Ohio, USA (1989), Eilat, Israel (1990), Paris, France (1991), Washington, USA (1992), Vancouver, Canada (1993), Santa Margherita Ligure, Italy (1994), Portland, USA (1995), Leuven, Belgium and Port Jefferson, USA (1997), Las Cruces, USA (1999), Paphos, Cyprus (2001), Copenhagen, Denmark (2002), Mumbai, India (2003), Saint Malo, France (2004) and Sitges, Spain (2005). The workshop aims at providing an informal meeting for the researchers working on logic-based tools for development and analysis of programs. This year we want to emphasize two aspects: on one hand we want to discuss the presentation, pragmatics and experiences of such tools; on the other one, we want to shift the traditional focus on environment tools for logic programming to logic-based environmental tools for programming in general. Specific topic areas relevant to the workshop include, but are not limited to: * tools for debugging and testing * tools for static and dynamic analysis * systems for program verification and validation * code generation from specifications * termination and non-termination analyzers * reasoners on occurs-check freeness and determinacy * profilers and performance analyzers * systems for types and modes analyzes * module systems * optimization tools. In addition to papers describing more conceptual work on environmental tools, we solicit papers describing the implementation of and experimentation with such tools. Submission guidelines --------------------- Length of papers can range from 2 to 17 pages, preferably in LNCS format. Authors are requested to submit their paper using the submission webpage at http://vampire.cs.man.ac.uk/WLPE-06/ Alternatively, authors can send a copy of their paper (in pdf or ps format) to the workshop coordinator (wva(a)info.fundp.ac.be) An informal proceedings will be published as a technical report of the University of Namur and distributed at the workshop. After the workshop, the proceedings will be publicly available on-line in the Computing Research Repository (CoRR). Important dates --------------- Submission: May 15, 2006 Notification: June 15, 2006 Camera-ready: July 10, 2006 Workshop: August 16, 2006 Workshop organizers ------------------- Susana Muñoz-Hernández (Universidad Politécnica de Madrid, Spain) Wim Vanhoof (coordinator) (Univeristy of Namur, Belgium) Program Committee ----------------- María Alpuente (Universidad Politécnica de Valencia, Spain) Mireille Ducassé (INSA/IRISA, Rennes, France) John Gallager (Roskilde University, Denmark) María García de la Banda (Monash University, Australia) José Manuel Gómez-Pérez (ISOCO Madrid, Spain) Gopal Gupta (University of Texas at Dallas, U.S.A) Moreno Falaschi (Università di Udine, Italy) Pat Hill (University of Leeds, U.K.) Michael Leuschel (Heinrich-Heine-Universitat Düsseldorf, Germany) Fred Mesnard (Université de La Réunion, France) Susana Muñoz-Hernández (Universidad Politécnica de Madrid, Spain) Kostis Sagonas (Uppsala University, Sweden) Alexander Serebrenik (Technische Universiteit Eindhoven, The Netherlands) Zoltan Somogyi (University of Melbourne, Australia) Wim Vanhoof (University of Namur, Belgium)

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GPCE 2006 Deadline Extension
by Emir Pasalic 26 Apr '06

26 Apr '06

Apologies for repeated posts. The GPCE 2006 deadline for technical paper submission has been extended to May 14. GPCE provides a venue for researchers and practitioners interested in foundational techniques for enhancing the productivity, quality and time-to-marked in software development that stems from deploying standard componentry and automating program generation. In addition to exploring cutting-edge techniques for developing generative component-based software, our goal is to foster further cross- fertilization between software engineering research community and the programming languages community. Changes: - There will be no pre-submission - Submission deadline: May 14, 2006, 23:59 Apia time (previously May 5) - Notification: June 28, 2005 For more information, check: http://www.program-transformation.org/GPCE06/

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[ANN] Hazakura - search-based MUA written in Haskell
by Jun Mukai 26 Apr '06

26 Apr '06

Dear all, I am pleased to announce the first release of hazakura, a search-based mail client. web page (to build): http://www.city5.org/hazakura/ source code: http://www.city5.org/haskellprog/hazakura/ You can get the source code using darcs as follows. darcs get http://www.city5.org/haskellprog/hazakura/ Although hazakura is written in Haskell, it uses Hyper Estraier as the search-engine, and QDBM as storage. So, you must install these libraries and their bindings. QDBM: http://qdbm.sourceforge.net/ binding: http://www.city5.org/haskellprog/qdbm/ Hyper Estraier: http://hyperestraier.sourceforge.net/ binding: http://www.city5.org/haskellprog/hstraier/ And also, you must install the following libraries: * wxWidgets and wxHaskell * Crypto The current status of hazakura is experimental. It lacks many fundamental functionalities and will have many bugs. But, it works (i.e. it can send, receive, search, and display mails). Any comments are welcome. Thanks, -- Jun Mukai mukai(a)jmuk.org

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speed of Binary serialization libraries
by Bulat Ziganshin 26 Apr '06

26 Apr '06

Hello haskell, i have performed a small test of serialization libraries speed, more to compare GHC's solution with my own. Tests was runned on 1GHz Duron. Each test reads or writes 100 mb of data splitted to 10 kb chunks - arrays or lists. Results are: GHC Binary (memory): Writing UArray: 21.652 secs Reading UArray: 17.064 secs Writing list: 21.231 secs Reading list: 22.562 secs GHC Binary (file): Writing UArray: 198.835 secs Reading UArray: 99.463 secs Writing list: 195.812 secs Reading list: 129.707 secs Other reincarnations of this module (jhc Binary, NewBinary) are slightly slower. Results of my own lib: AltBinary (memory, without bounds checking): Writing UArray: 1.933 secs Reading UArray: 1.683 secs Writing list: 1.832 secs Reading list: 2.744 secs AltBinary (memory): Writing UArray: 4.847 secs Reading UArray: 6.930 secs Writing list: 4.246 secs Reading list: 8.232 secs AltBinary (file): Writing UArray: 12.368 secs Reading UArray: 8.312 secs Writing list: 9.814 secs Reading list: 9.744 secs Testbed is included. -- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com

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