June 2009 - Glasgow-haskell-users

is the library iconv necessary for haskeline?
by Christian Maeder 08 Jun '09

08 Jun '09

Hi, building ghc-6.10.3 under x86 solaris eventually failed with: Configuring ghc-bin-6.10.3... cabal-bin: At least the following dependencies are missing: haskeline -any gmake[3]: *** [boot.stage.2] Error 1 I think, haskeline is not build because libiconv is missing: -bash-3.00$ ./Setup configure --prefix=/NONEXISTENT --bindir=/NONEXISTENT --libdir=/NONEXISTENT --libexecdir=/NONEXISTENT --datadir=/NONEXISTENT --docdir=/NONEXISTENT --haddockdir=/NONEXISTENT --htmldir=/NONEXISTENT --with-compiler=/export/local1/home/maeder/haskell/ghc-6.10.3/ghc/stage1-inplace/ghc --with-hc-pkg=/export/local1/home/maeder/haskell/ghc-6.10.3/utils/ghc-pkg/install-inplace/bin/ghc-pkg --libsubdir=$pkgid --with-gcc=gcc --with-ld=/usr/ccs/bin/ld --with-alex=/home/pub-bkb/bin/alex --with-happy=/home/pub-bkb/bin/happy --configure-option='--with-cc=gcc --with-hsc2hs=/export/local1/home/maeder/haskell/ghc-6.10.3/utils/hsc2hs/install-inplace/bin/hsc2hs --haddock-options=--use-contents=../index.html --use-index=../doc-index.html' --enable-library-profiling --enable-split-objs Configuring haskeline-0.6.1.5... checking whether to use -liconv... Setup: Unable to link against the iconv library. I wonder how this check for -liconv is generated. I have a file /usr/include/iconv.h but not file /usr/lib/libiconv.* Under Linux I've installed successfully http://www.haskell.org/ghc/dist/6.10.3/ghc-6.10.3-i386-unknown-linux-n.tar.… and I was able to install http://hackage.haskell.org/packages/archive/haskeline/0.6.1.6/haskeline-0.6… without libiconv! > ./Setup configure Configuring haskeline-0.6.1.6... checking whether to use -liconv... not needed. However, the mere existence of /usr/local/lib/libiconv* files causes configure to use -liconv: checking whether to use -liconv... using -liconv. I would like to avoid this (unnecessary?) dependency (without removing /usr/local/lib). (/usr/local/lib is _not_ part of LD_LIBRARY_PATH and should not be searched by gcc, but is still somehow found and used.) Are there any configure options that work? (The cabal-flag libiconv is false.) How is "checking whether to use ..." generated? Is libiconv really necessary under Solaris? Cheers Christian

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Should exhaustiveness testing be on by default?
by Don Stewart 07 Jun '09

07 Jun '09

I'm not sure I'd want -Wall on by default (though being -Wall clean is very good). But exhaustive pattern checking might well help out a lot of people coming from untyped backgrounds. http://ocaml.janestreet.com/?q=node/64 Ron's also wondering why exhaustive pattern checking isn't on ? Anyone know why it isn't the default? -- Don

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Job for someone: make a VM image for GHC development
by Simon Marlow 05 Jun '09

05 Jun '09

I forget who mentioned this to me, but I think it's a great idea. Things like VirtualBox and VMWare are pretty easy to install and set up these days. It wouldn't be hard for someone to create a VM image of a Linux system with a complete GHC development environment set up and ready to go. This would have a lot of benefits: * Easy to buy into: just install VirtualBox (or whatever), download the image, register it and away you go. * Would make the barrier to entry much lower for someone who wants to make a small change, e.g. to the docs, or a library. validate and 'darcs send' would Just Work. * Would serve as an example of best-practice in setting up a GHC development environment. The hard part might be optimising the install so that we don't end up with an enormous image file. We'd probably need to find a suitably minimal Linux install, or start from an existing minimal Linux VM image. Anyone feeling keen? Cheers, Simon

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Re: Job for someone: make a VM image for GHC development
by Philip K.F. Hölzenspies 05 Jun '09

05 Jun '09

Dear Simon, et al. I've looked around trying to pick up information on tiny installations of Linux. It seems most modern distributions think 200MB is a pretty barebone installation. There's a claim by someone that (s)he got a Tiny Gentoo installation into 5MB. I'll be looking into that this evening. Of the options given (installer vs. VM image), I have most faith in the VM image. From what I've seen, installers are still quite large (summed total of all downloads required) compared to a to-the-point installation. Could you be slightly more specific on what you want in the image for it to be a GHC development environment? I presume darcs is one. Also, I presume the GHC source tree isn't. Compiler-wise; do you want/need gcc on a system like this, if so, do you still want a binary GHC there? If a binary GHC is desired, do you want a bare minimum (w/o extralibs, possibly older version), the more elaborate (w/ extralibs), or the whole package (Haskell Platform)? Possibly the easiest VM image to maintain just has the minimum requirements to run emerge and a script that, on first boot of the image, emerges the haskell platform and darcs. This way, you don't need to update the VM image with updates of GHC (or updated dependencies of the GHC source tree on newer GHC versions). The upside is a very fast download of the image, but the downside is a very slow first boot of the image. Regards, Philip

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[Fwd: OSX installer -- first draft]
by Duncan Coutts 04 Jun '09

04 Jun '09

OSX users, please could you try out Gregory's Haskell Platform package below and send commentary to the platform list, or file tickets in the platform trac, that'd be great. http://trac.haskell.org/haskell-platform/newticket?component=OSX%20installer The plan is that for ghc-6.12 and onwards, that this will be the primary way that end-users get their Haskell goodness on OSX, so it's important that you provide feedback now so that we can get the thing working nicely and try to make everyone happy. I'm sure Gregory would also appreciate help in working out how to make the OSX .pkg tools behave properly. Duncan -------- Forwarded Message -------- > From: Gregory Collins <greg(a)gregorycollins.net> > To: haskell-platform <haskell-platform(a)projects.haskell.org> > Subject: OSX installer -- first draft > Date: Tue, 02 Jun 2009 00:20:18 -0400 > > Hi all, > > After months of intense frustration I have something approaching a > reasonable OSX installer for the Haskell Platform. I'd appreciate it if > some OSX hackers could try it out. > > The installer can be downloaded from: > http://gregorycollins.net/static/haskell/haskell-platform-2009.2.0.1-alpha1… > > Please do me a favour and don't link there from the haskell platform > website :) > > Features/caveats: > > * it presupposes GHC-6.10.3 is installed from the binary distro. The > final release will bundle the two together in a .dmg file. > > * it installs the platform libraries and executables to > /Library/Framework/HaskellPlatform.framework, registers the > libraries with GHC, and symlinks the binaries to /usr/local/bin > > * I had to build the distro package by hand using Apple's GUI tool > because I can't figure out how to do it otherwise -- and not for > lack of trying, either, I reckon I've put 20-30 man-hours into > trying to figure it out -- thanks Apple! Similarly, for the life of > me I cannot figure out how to bundle GHC and the platform libs > together into one installer. > > * There's some haddock documentation in there but I'm not sure how > nicely it's cross-linked. > > * The code is a mess, I need to clean it up (and systematize the > process) before it's fit for inclusion into the project. > > * I've done some (very) limited testing but given how difficult the > whole project has been, I fully expect problems. > > Sorry about how long it's taken -- I'm getting married on Saturday (!) > so finding time to work on this has been difficult indeed. > > G.

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space leak due to optimisations and/or newtypes
by Sebastian Fischer 04 Jun '09

04 Jun '09

Hello, I have written a Haskell program that runs much more efficiently without optimisations than with optimisations. Compiled without optimisations it finishes in about 15 seconds and runs in constant space (< 3 MB), with optimisations (both -O and -O2) it consumed all my RAM in less than 30 seconds before I killed it. The program contains four occurrences of the identity function 'id'. All of them are superflous from a declarative point of view. If I remove any of them (one is enough) then the program finishes in about 10 seconds and runs in constant space (< 3 MB) with optimisations. The (attached) program is a condensed version of a program that uses newtypes. Originally, the identity functions where newtype con- and destructors. The original program consumes a lot of memory both with and without optimisations. A version where I have inlined some newtypes runs in constant space. I have used GHC 6.10.1 on Mac OS X. Is this behaviour intended, is it a known/fixed issue of GHC 6.10.1 or should I file a bug report? Cheers, Sebastian ------- {-# LANGUAGE RankNTypes #-} newtype S a = S { unS :: forall b . (a -> Int -> [b]) -> Int -> [b] } ret x = S (\c -> c x) a `bind` f = S (\c -> unS a (\x -> unS (f x) c)) zero = S (\c _ -> []) plus a b = S (\c -> id (\d -> if d==0 then [] else id (unS a c) (d-1) ++ id (unS b c) (d-1))) runS :: S a -> [a] runS a = concatMap (\d -> id (run a) d) [10000] run :: S a -> Int -> [a] run a = unS a (\x _ -> [x]) natSum :: S Int natSum = anyof [1..] `bind` \x -> anyof [1..] `bind` \y -> ret (x+y) where anyof = foldr plus zero . map ret main = print . length $ runS natSum ------- -- Underestimating the novelty of the future is a time-honored tradition. (D.G.)

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Choosing implementation depending on class instances using rewriting rules
by Milan Straka 04 Jun '09

04 Jun '09

Hi, I am interesting in writing a method nub in such a way, that it will use O(N^2) trivial algorithm for types with equality only, and O(N log N) algorithm for comparable types. I would like to say class Nub where nub :: [a] -> [a] instance Ord a => Nub a where nub = nubOrd instance Eq a => Nub a where nub = nubEq which is of course not valid Haskell. I tried using GHC rewriting rules to achieve this. My first try was {-# NOINLINE nub #-} nub :: Eq a => [a] -> [a] nub xs = ... nubOrd :: Ord a => [a] -> [a] nubOrd xs = ... {-# RULES "nub/nubOrd" nub = nubOrd #-} which does not work either, because of missing an Ord a context. I was not able to write the rule which would fire. Is there a way to write such a rewriting rule or there is no way of acquiring the Ord dictionary in rewrite rule? Or does anyone know any other way of implementing such a nub without explicitly listing all Ord instances? I wish you a nice day, Milan Straka PS: Listing {-# RULES "nub/nubOrd Int" nub = nubOrd :: [Int]->[Int] #-} for all Ord instances would work, but ...

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Problem with profiling
by Marco Túlio Gontijo e Silva 03 Jun '09

03 Jun '09

Hello, recently there was a thread about a problem in profiling in gtk2hs-users, and it was menitoned that this could be a GHC6 bug. The problem is described in http://sourceforge.net/mailarchive/forum.php?thread_name=1242762143.18742.2… . Do you think this is a gtk2hs specific problem, or is it something about GHC? Greetings. -- marcot http://marcot.iaaeee.org/

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ghc - force library search order
by John Lask 02 Jun '09

02 Jun '09

----- Original Message ----- From: "Duncan Coutts" <duncan.coutts(a)worc.ox.ac.uk> To: "John Lask" <jvlask(a)hotmail.com> Sent: Friday, May 29, 2009 8:09 PM Subject: Re: [Haskell-cafe] ghc - force library search order > On Fri, 2009-05-29 at 18:08 +1000, John Lask wrote: >> I need to force a library to be searched for unresolved symbols after all >> other libraries have been searched, and I would rather not resort to >> constructing the linker command line directly. Is there a way to do this? >> >> i.e. I want for example -lfoo to appear after all other haskell libraries >> and before system libraries (for example -lmsvcrt) once ghc has >> constructed >> the link command. i.e. how is it possible to coerce ghc into respecting >> dependencies between the libraries. GHC does a good job in general with >> native libraries, but there are allways corner cases. >> >> I have a feeling this is not possible, but it dosn't hurt to ask. > > If you don't get a reply then ask on the ghc users mailing list. > > Duncan > >

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IFL 2009 - 2nd Call for papers
by Jost Berthold 01 Jun '09

01 Jun '09

Apologies for multiple copies. Jost Berthold Call for Papers IFL 2009 Seton Hall University SOUTH ORANGE, NJ, USA http://tltc.shu.edu/blogs/projects/IFL2009/ ** NEW ** Accomodations information available: http://tltc.shu.edu/blogs/projects/IFL2009/accommodations.html Jane Street Capital has joined IFL 2009 as a sponsor ********* The 21st International Symposium on Implementation and Application of Functional Languages, IFL 2009, will be held for the first time in the USA. The hosting institution is Seton Hall University in South Orange, NJ, USA and the symposium dates are September 23-25, 2009. It is our goal to make IFL a regular event held in the USA and in Europe. The goal of the IFL symposia is to bring together researchers actively engaged in the implementation and application of functional and function-based programming languages. IFL 2009 will be a venue for researchers to present and discuss new ideas and concepts, work in progress, and publication-ripe results related to the implementation and application of functional languages and function-based programming. Following the IFL tradition, IFL 2009 will use a post-symposium review process to produce a formal proceedings which will be published by Springer in the Lecture Notes in Computer Science series. All participants in IFL 2009 are invited to submit either a draft paper or an extended abstract describing work to be presented at the symposium. These submissions will be screened by the program committee chair to make sure they are within the scope of IFL and will appear in the draft proceedings distributed at the symposium. Submissions appearing in the draft proceedings are not peer-reviewed publications. After the symposium, authors will be given the opportunity to incorporate the feedback from discussions at the symposium and will be invited to submit a revised full arcticle for the formal review process. These revised submissions will be reviewed by the program committee using prevailing academic standards to select the best articles that will appear in the formal proceedings. TOPICS IFL welcomes submissions describing practical and theoretical work as well as submissions describing applications and tools. If you are not sure if your work is appropriate for IFL 2009, please contact the PC chair at ifl2009(a)shu.edu. Topics of interest include, but are not limited to: language concepts type checking contracts compilation techniques staged compilation runtime function specialization runtime code generation partial evaluation (abstract) interpretation generic programming techniques automatic program generation array processing concurrent/parallel programming concurrent/parallel program execution functional programming and embedded systems functional programming and web applications functional programming and security novel memory management techniques runtime profiling and performance measurements debugging and tracing virtual/abstract machine architectures validation and verification of functional programs tools and programming techniques FP in Education PAPER SUBMISSIONS Prospective authors are encouraged to submit papers or extended abstracts to be published in the draft proceedings and to present them at the symposium. All contributions must be written in English, conform to the Springer-Verlag LNCS series format and not exceed 16 pages. The draft proceedings will appear as a technical report of the Department of Mathematics and Computer Science of Seton Hall University. IMPORTANT DATES Registration deadline August 15, 2009 Presentation submission deadline August 15, 2009 IFL 2009 Symposium September 23-25, 2009 Submission for review process deadline November 1, 2009 Notification Accept/Reject December 22, 2009 Camera ready version February 1, 2010 PROGRAM COMMITTEE Peter Achten University of Nijmegen, The Netherlands Jost Berthold Philipps-Universität Marburg, Germany Andrew Butterfield University of Dublin, Ireland Robby Findler Northwestern University, USA Kathleen Fisher AT&T Research, USA Cormac Flanagan University of California at Santa Cruz, USA Matthew Flatt University of Utah, USA Matthew Fluet Toyota Technological Institute at Chicago, USA Daniel Friedman Indiana University, USA Andy Gill University of Kansas, USA Clemens Grelck University of Amsterdam/Hertfordshire, The Netherlands/UK Jurriaan Hage Utrecht University, The Netherlands Ralf Hinze Oxford University, UK Paul Hudak Yale University, USA John Hughes Chalmers University of Technology, Sweden Patricia Johann University of Strathclyde, UK Yukiyoshi Kameyama University of Tsukuba, Japan Marco T. Morazán (Chair) Seton Hall University, USA Rex Page University of Oklahoma, USA Fernando Rubio Universidad Complutense de Madrid, Spain Sven-Bodo Scholz University of Hertfordshire, UK Manuel Serrano INRIA Sophia-Antipolis, France Chung-chieh Shan Rutgers University, USA David Walker Princeton University, USA Viktória Zsók Eötvös Loránd University, Hungary PETER LANDIN PRIZE The Peter Landin Prize is awarded to the best paper presented at the symposium every year. The honored article is selected by the program committee based on the submissions received for the formal review process. The prize carries a cash award equivalent to 150 euros.

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