- Haskell-Cafe - Haskell.org

Diagnose stack space overflow
by Logo Logo 08 Jul '11

08 Jul '11

Hi, For the following error: Stack space overflow: current size 8388608 bytes. Use `+RTS -Ksize -RTS' to increase it. I want to find out the culprit function and rewrite it tail-recursively. Is there a way to find out which function is causing this error other than reviewing the code manually? Thanks, Loganathan

7 6

ANNOUNCE: hacphi satellite in berlin july 29-31
by Matthias Fischmann 08 Jul '11

08 Jul '11

yet another hackathon: in case you wanted to join the philadelphia haskell hackathon but decided it's too far away (or in case you happen to be anywhere near and think this is a great opportunity), please join us in berlin: http://haskell.org/haskellwiki/Hac_%CF%86#Berlin_satellite admission is free. we have limited seats, so don't wait too long! hope to see you there, cheers, matthias

1 0

Re: [Haskell-cafe] Diagnose stack space overflow
by John Lato 08 Jul '11

08 Jul '11

> From: Logo Logo <saraslogo(a)gmail.com> > > Hi, > > For the following error: > > Stack space overflow: current size 8388608 bytes. > Use `+RTS -Ksize -RTS' to increase it. > > I want to find out the culprit function and rewrite it tail-recursively. Is > there a way to find out which function is causing this error other > than reviewing the code manually? > I'd like to point out that a stack-space overflow in Haskell isn't quite the same thing as in other functional languages. In particular, it's possible for tail-recursive functions to overflow the stack because of laziness. Consider this tail-recursive sum function: > trSum :: [Int] -> Int > trSum l = go 0 l > where > go acc [] = acc > go acc (x:xs) = go (acc+x) xs It's tail-recursive. But if you enter this in ghci and run it, you'll find that it uses increasing stack space, and will likely cause a stack overflow for large enough inputs. The problem is that the accumulator 'acc' isn't strict and builds up a thunk of the form: 0+n1+n2+...+nn The solution is to add strictness. For this example, a '!' on the accumulator will do. GHC will sometimes spot cases where extra strictness is helpful (it'll figure this one out when compiled with -O), but it often needs help. I'd recommend Edward Yang's series of blog posts about debugging, space leaks, and the Haskell heap. One useful article is http://blog.ezyang.com/2011/05/anatomy-of-a-thunk-leak/ , but you may want to start at the beginning of the heap series. John L.

2 1

Re: [Haskell-cafe] NLP libraries and tools?
by wren ng thornton 08 Jul '11

08 Jul '11

On 7/7/11 3:38 AM, Aleksandar Dimitrov wrote: > On Wed, Jul 06, 2011 at 07:27:10PM -0700, wren ng thornton wrote: >> I definitely agree with the iteratees comment, but I'm curious about the >> leaks you mention. I haven't run into leakiness issues (that I'm aware of) >> in my use of ByteStrings for NLP. > > The issue is this: strict ByteStrings retain pointers to the original chunk. The > chunk is probably bigger than you'd want to keep in memory, if you, say, wanted > to just keep one or two words. In my case, the chunk was some 65K (that was my > Iteratee chunk size.) Oh, that issue. Yeah, I maintain an intern table and make sure that the copy in the table is a trimmed copy instead of keeping the whole string alive. I guess I should factor that part of my tagger out into a separate package :) I didn't know if you meant there was a technical issue, e.g. something about the fact that ByteStrings uses pinned memory (whereas Text doesn't IIRC). -- Live well, ~wren

1 0

NVIDIA's CUDA and Haskell
by Vasili I. Galchin 08 Jul '11

08 Jul '11

Hi, NVIDIA's CUDA library seems to be really hot in the massively parallel world: http://www.nvidia.com/object/cuda_home_new.html. I realize that given CUDA seems to be implemented in an extension of ANSI C that it is pervaded by statefulness. However, is there any effort to build "a bridge" between Haskell and CUDA, foreign language bindings or maybe better yet a monad to encapsulate state?? Kind regards, Vasili

4 6

Jenkins/Hudson support for GHC warnings?
by Bryan O'Sullivan 07 Jul '11

07 Jul '11

Hi, folks - I know there are quite a few Haskell projects using the Jenkins (formerly Hudson) continuous build system, and I wonder if anyone has figured out how to get it reliably collecting errors and warnings from GHC. The standard warnings plugin<https://wiki.jenkins-ci.org/display/JENKINS/Warnings+Plugin>does a bad job - it tends to identify random (sometimes even empty) bits of build output as warnings. If you've configured it to behave better with GHC / hpc / QuickCheck / cabal-install, you'd be doing us a great service by sharing your tricks! Thanks, Bryan.

1 0

how to change a process name
by Kazu Yamamoto 07 Jul '11

07 Jul '11

Hello, I would like to know how to change a process name in Haskell. When we are programming in C, we can change it by overriding argv on Unix. But I cannot find the same way to do in Haskell. Can anyone suggest how in Haskell? I'm not talking about the result of System.Environment.getProgName but talking about the process name which we can see by the "ps" command. Thanks. --Kazu

2 1

Web Framework to Show Experimental Data
by Dmitri O.Kondratiev 07 Jul '11

07 Jul '11

Hi! I am looking for the Haskell libraries to quickly create some Web Framework to Show Experimental Data. Please share your experience and ideas. What tools would you chose for such a framework: == Architecture There are several unsynchronized processes: 1) Finder - demon that periodically searches and collects JSON data from the Web and stores this data in some sort of Archive (DB). 2) Processor - demon that periodically process new data from Archive collected by Finder and stores results of its work in the same Archive. 3) Web application that shows processed data in a browser. == General Requirements *** Main requirement - simplicity and high speed of development *** - Max Data storage capacity - 10 Mb - Max number of Web users - 50 - Web UI shows what Archive has at the moment of user request. == Web UI Requirements - Multi-page view of long data sets (some sort of scrolling) - Simple graphs and charts (desirable) == Questions 1) What to use for the Archive? Though input data is in JSON format, data generated from it is binary vectors. Not sure that CouchDB is a good choice in this case. What simple (Haskell lib + DB) combination one may advise that support concurrent read / write access with simple locking (don't need full transactional support)? 2) Web framework? Don't need AJAX, just basic stuff but simple and easy to code forms? Thanks!

2 3

CFP: PADL'12 - Practical Aspects of Declarative Languages 2012
by Claudio Russo 07 Jul '11

07 Jul '11

[Apologies if you receive multiple copies.] Call for Papers =============== 14th International Symposium on Practical Aspects of Declarative Languages (PADL 2012) http://research.microsoft.com/~crusso/padl12 Philadelphia, Pennsylvania, USA, January 23-24, 2012 Co-located with ACM POPL'12 Abstract/Paper submission deadline: September 10th/17th, 2011 Conference Description ====================== Declarative languages build on sound theoretical bases to provide attractive frameworks for application development. These languages have been successfully applied to many different real-world situations, ranging from data base management to active networks to software engineering to decision support systems. New developments in theory and implementation have opened up new application areas. At the same time, applications of declarative languages to novel problems raise numerous interesting research issues. Well-known questions include designing for scalability, language extensions for application deployment, and programming environments. Thus, applications drive the progress in the theory and implementation of declarative systems, and benefit from this progress as well. PADL is a forum for researchers and practitioners to present original work emphasizing novel applications and implementation techniques for all forms of declarative concepts, including, functional, logic, constraints, etc. Topics of interest include, but are not limited to: * Innovative applications of declarative languages * Declarative domain-specific languages and applications * Practical applications of theoretical results * New language developments and their impact on applications * Declarative languages and Software Engineering * Evaluation of implementation techniques on practical applications * Practical experiences and industrial applications * Novel uses of declarative languages in the classroom * Practical extensions such as constraint-based, probabilistic, and reactive languages. PADL'12 welcomes new ideas and approaches pertaining to applications and implementation of declarative languages. In this occasion PADL is co-located, as traditionally, with ACM POPL, which will be held immediately following PADL, January 25-27. The symposium will be held in Philadelphia, Pennsylvania, USA. Important Dates and Submission Guidelines ========================================= Abstract Submission: September 10, 2011 Paper Submission: September 17, 2011 Notification: October 22, 2011 Camera-ready: November 5, 2011 Symposium: January 23-24, 2012 Authors should submit an electronic copy of the full paper in PDF using the Springer LNCS format. The submission will be done through EasyChair conference system. If electronic submission is impossible, please contact the program chairs for information on how to submit hard copies. All submissions must be original work written in English. Submissions must be unpublished and not submitted for publication elsewhere. Work that already appeared in unpublished or informally published workshops proceedings may be submitted. PADL'12 will accept both technical and application papers: * Technical papers must describe original, previously unpublished research results. Technical papers must not exceed 15 pages in Springer LNCS format. * Application papers are a mechanism to present important practical applications of declarative languages that occur in industry or in areas of research other than Computer Science. Application papers will be published in the Springer-Verlag conference proceedings, and will be presented in a separate session. Application papers are expected to describe complex and/or real-world applications that rely on an innovative use of declarative languages. Application descriptions, engineering solutions and real-world experiences (both positive and negative) are solicited. The limit for application papers is 6 pages in Springer LNCS format. Program Committee ================= Marcello Balduccini, Intelligent Systems Department, Kodak Research Labs Edwin Brady, University of St Andrews, Scotland Henning Christiansen, Roskilde University, Denmark Agostino Dovier, University of Udine, Italy Matthew Flatt, University of Utah, USA Gopal Gupta, University of Texas at Dallas, USA John Hughes, Chalmers University of Technology, Sweden; Quviq AB Gabriele Keller, University of New South Wales, Australia Lunjin Lu, Oakland University, USA Marc Pouzet, École normale supérieure, France Ricardo Rocha, University of Porto, Portugal Andreas Rossberg, Google Germany GmbH, Germany Claudio Russo, Microsoft Research Cambridge, UK (co-chair) Kostis Sagonas, Uppsala Univeristy, Sweden Satnam Singh, Microsoft Research Cambridge, UK Zoltan Somogyi, University of Melbourne, Australia Eijiro Sumii, Tohoku University, Japan Terrance Swift, Universidade Nova de Lisboa, Portugal; Johns Hopkins University, USA Andrew Tolmach, Portland State University, USA Jan Wielemaker, University of Amsterdam, The Netherlands Roland Yap, National University of Singapore, Republic of Singapore Kwangkeun Yi, Seoul National University, Korea Neng-Fa Zhou, Brooklyn College, City University of New York, USA (co-chair) Contacts ======== For additional information about papers and submissions, please contact the Program Chairs: Claudio Russo Microsoft Research Cambridge,UK Email: crusso <AT> microsoft <DOT> com Neng-Fa Zhou Brooklyn College, The City University of New York, USA Email: zhou <AT> sci <DOT> brooklyn <DOT> cuny <DOT> edu With the Cooperation of ======================= The Association for Logic Programming (ALP) ACM SIGPLAN ===================================

1 0

Installation failure crypto-api on MAC
by Neil Davies 07 Jul '11

07 Jul '11

Hi Anyone out there seen this - building > Building crypto-api-0.6.3... > [2 of 9] Compiling Crypto.CPoly ( Crypto/CPoly.hs, dist/build/Crypto/CPoly.o ) several minutes later > ghc: could not execute: /usr/bin/gcc looks like it is silently running out of memory (I understand that this particular module is tough for the compiler due to the large 'constant' table inside it) I'm using "The Glorious Glasgow Haskell Compilation System, version 7.0.3" on (uname -a follows) Darwin mac-server-a.local 10.7.0 Darwin Kernel Version 10.7.0: Sat Jan 29 15:17:16 PST 2011; root:xnu-1504.9.37~1/RELEASE_I386 i386 Suggestions anyone? Neil

1 0