April 2009 - Haskell-Cafe

community.haskell.org unreachable?
by Claus Reinke 06 Apr '09

06 Apr '09

I seem to be having problems reaching anything on that server. Does anyone know what is going on, or who to contact? It would help if the haskellwiki page http://www.haskell.org/haskellwiki/Haskell.org_domain would mention the admin address directly, instead of referring to http://community.haskell.org/admin/ which is also unreachable. Claus

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Re: [Haskell-cafe] ANN: SVGFonts 0.1
by Tillmann Vogt 06 Apr '09

06 Apr '09

John Van Enk schrieb: > This sounds very cool. Is is just a program, or is there a library sitting > behind it? From your .cabal file, it seems to be just a binary program. > > Is this correct? > > http://hackage.haskell.org/packages/archive/SVGFonts/0.1/SVGFonts.cabal > > On Mon, Apr 6, 2009 at 1:22 PM, Tillmann Vogt > <Tillmann.Vogt(a)rwth-aachen.de>wrote: > It is a real library made of pure Haskell. What is wrong with my .cabal file?

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Making videos of your project
by Don Stewart 06 Apr '09

06 Apr '09

Hey guys, I've been making quick youtube videos of projects to convey what they do. Here, for example, using Tim Docker's Charts library in ghci: http://www.youtube.com/watch?v=2Lqzygxvus0 (Click on the HD button for higher res). Or one of Neil Brown's "SG" OpenGL graphics library, http://www.youtube.com/watch?v=tJ6AtfcorkY You can create your own really simply: 1. install 'recordmydesktop' I use: recordmydesktop --no-sound --v_bitrate 2000000 2. type 'recordmydesktop' 3. do something with haskell 4. hit control-C 5. upload out.ogv to youtube If you're a library author of one of the 2 or 3D packages, please consider video along with other "why I want to use this" material. -- Don

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ANN: SVGFonts 0.1
by Tillmann Vogt 06 Apr '09

06 Apr '09

I hereby publish my first library in Haskell. SVGFonts 0.1 It parses the pretty unknown SVG Font format to produce outlines of characters. The big advantage of this format is that it is XML, which means easy parsing and manipulating. Because I haven't found any svg-files on the Internet the typical way is to convert a more popular format (i.e. .ttf) into SVG Font via fontforge. This library may be useful if you want to have a direct access to specific algorithms which is of course harder when using a binding (i.e. Jeff Heards FTGL binding). The speed is improvable (see TO DO list) and since since this is my first library there might some errors which I am not aware of (please tell me). I also wonder why the library doesn't appear under graphics on hackage, although there is Category: Graphics in my cabal file. Depending on which library I like more, I will maybe integrate SVGFonts into LambdaCube or Fieldtrip Cheers, Tillmann

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Re: [Haskell-cafe] Combining sequences
by michael rice 06 Apr '09

06 Apr '09

I downloaded it and it appears more complicated than just adding files to a directory. There's a setup and a build, and no assurances it will work with Hugs. I think I'll wait for more information. Michael --- On Mon, 4/6/09, Thomas Hartman <tphyahoo(a)gmail.com> wrote: From: Thomas Hartman <tphyahoo(a)gmail.com> Subject: Re: [Haskell-cafe] Combining sequences To: "michael rice" <nowgate(a)yahoo.com> Cc: "Henning Thielemann" <lemming(a)henning-thielemann.de>, haskell-cafe(a)haskell.org Date: Monday, April 6, 2009, 12:26 AM It's not in hugs, nor in ghc. It's just in hackage. However, by the looks of it, you should probably be able to use it in hugs. I didn't actually check this, but the cabal file didn't name any fancy extensions, so it looks pretty cross-compiler. You can just go to http://hackage.haskell.org/cgi-bin/hackage-scripts/package/utility-ht-0.0.4 wget http://hackage.haskell.org/packages/archive/utility-ht/0.0.4/utility-ht-0.0… untar and put them with the rest of the files your hugs compiler uses for package import. (I don't actually know how package installation works in hugs... isn't it just put the files into a dir?) thomas. 2009/4/5 michael rice <nowgate(a)yahoo.com>: > Thanks. It looks like mergeBy will do the job, but is it available in Hugs? > > Michael > > > --- On Sun, 4/5/09, Henning Thielemann <lemming(a)henning-thielemann.de> > wrote: > > From: Henning Thielemann <lemming(a)henning-thielemann.de> > Subject: Re: [Haskell-cafe] Combining sequences > To: "michael rice" <nowgate(a)yahoo.com> > Cc: haskell-cafe(a)haskell.org > Date: Sunday, April 5, 2009, 9:09 PM > > > On Sat, 4 Apr 2009, michael rice wrote: > >> Is there a simple way to combine two sequences that are in ascending order >> into a single >> sequence that's also in ascending order? An example would be the squares >> [1,4,9,16,25..] >> combined with the cubes [1,8,27,64,125..] to form [1,1,4,8,9,16,25,27..]. > > http://hackage.haskell.org/packages/archive/utility-ht/0.0.4/doc/html/Data-… > > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > >

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Unary Minus
by Paul Keir 06 Apr '09

06 Apr '09

If I use :info (-) I get information on the binary minus. Is unary minus also a function? Thanks, Paul

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Questions about slow GC with STArray
by FFT 06 Apr '09

06 Apr '09

I've been following with interest the recent discussions on reddit about the extremely slow hash tables in Haskell compared to F# and OCaml, and as I understood it, this performance problem is caused by GC not liking mutable arrays http://hackage.haskell.org/trac/ghc/ticket/650 It appears from the discussion there that this is more than a simple bug, but a fundamental difficulty (slow writes vs slow GC trade-off). What I'm wondering though is how can this be unique to GHC: all arrays in OCaml and probably F# are mutable (and usually unboxed). How is this problem addressed there? Why is this supposed to be specific to boxed arrays only: wouldn't GC have to scan the whole mutable array whether it's boxed or unboxed?

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EclipseFP proposal for Google Summer of Code
by Thomas ten Cate 06 Apr '09

06 Apr '09

To everyone involved in the Google Summer of Code program, I have submitted a GSoC proposal to work on EclipseFP, the Haskell plugin for Eclipse. The proposal is crossposted to both haskell.org and the Eclipse Foundation, each in their respective templates. This is also stated at the top of the proposal. I send this e-mail because of possible scheduling issues: I will be away starting on April 15. So, if you want to ask me things, have suggestions for improvement, or want to do an interview or something, this can only be done *before* that date. This is also stated in the proposal, but since I have no idea how the proposals are processed by the mentoring organizations, I figured that an explicit notification would be a good idea. For your convenience, here are links to the proposal. haskell.org version: http://socghop.appspot.com/student_proposal/show/google/gsoc2009/thomastc/t… and also on http://docs.google.com/Doc?id=dfmvb7sr_13fzdg5qhr Eclipse Foundation version: http://socghop.appspot.com/student_proposal/show/google/gsoc2009/thomastc/t… and also on http://docs.google.com/Doc?id=dfmvb7sr_15gb9258fg If my schedule causes any problems, please let me know. Also, comments on the proposal in general would be much appreciated. Thanks, Thomas P.S. I hope it's okay that I post this to the haskell-cafe list as well; since haskell.org has no GSoC-specific mailing list, it seems to be the most appropriate place that I could find.

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high probability of installation problems and quality of the glorious implementation
by FFT 06 Apr '09

06 Apr '09

I'm still learning Haskell and also evaluating whether I want to use the language in my work. It seems like a fascinating language so far (although I don't know if laziness will be a detriment later for me eventually), but I'm a bit worried about the overall quality of its GHC implementation. For example, I tried installing GHC-6.10.2 on my Ubuntu 8.04 machine (probably the most mainstream Linux these days). 1st attempt: binary => failed "the impossible happened, report bug" (I think it's already in bugzilla for an even earlier version) 2nd attempt: source and docs => followed README, but "make" failed while building docs 3rd attempt: source only, no docs => make install succeeded, but ghci now seems to have its "readline" screwed up (no editing, can't quit even with Ctrl-C or Ctrl-D), while Ubuntu-bundled 6.8.* ghci works fine in this regard. If these kinds of issues are common only during installation, I can live with that, but if GHC is flaky overall, having to deal with this may cancel out whatever productivity advantages Haskell provides. If the quality of the installation procedures is different from the compiler itself, can you explain why?

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minor typo in "The Haskell 98 Report"
by Benjamin L.Russell 06 Apr '09

06 Apr '09

Today, as I was reading through "The Haskell 98 Report" (see http://www.haskell.org/onlinereport/) I came across a minor typo, but it seems that the only way to fix such typos is to report them on one of the Haskell mailing lists; viz.: >The original committees ceased to exist when the original Haskell 98 Reports were published, so every change was instead proposed to the entire Haskell mailing list. Therefore, please allow me to report this typo, though minor, here, as follows: The Haskell 98 Report - Preface (see http://www.haskell.org/onlinereport/preface-jfp.html) under the heading "Haskell 98: language and libraries," fourth paragraph, second line: >If these program were to be portable, a set of libraries would have to be standardised too. should be as follows: >If these programs were to be portable, a set of libraries would have to be standardised too. (I.e., the word "program" should be plural.) Is this the proper place to report any forthcoming similar typos? -- Benjamin L. Russell -- Benjamin L. Russell / DekuDekuplex at Yahoo dot com http://dekudekuplex.wordpress.com/ Translator/Interpreter / Mobile: +011 81 80-3603-6725 "Furuike ya, kawazu tobikomu mizu no oto." -- Matsuo Basho^

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