- Haskell-Cafe - Haskell.org

Re: [Haskell] ANNOUNCE: colour 0.0.0
by Henk-Jan van Tuyl 25 Oct '08

25 Oct '08

On Wed, 22 Oct 2008 02:12:05 +0200, <roconnor(a)theorem.ca> wrote: > http://hackage.haskell.org/cgi-bin/hackage-scripts/package/colour-0.0.0 > > I hope for this library to become the standard colour library for > Haskell. Most software does not properly blend colours because they fail > to gamma-correct the colours before blending. Hopefully by using this > library, Haskell programs dealing with colour blending will avoid this > problem. > > I am making an early release of my colour library to get some feedback. > I am especially interested in getting feedback on the interfaces: should > functions be renamed, should functions be moved, etc. Should I put black > and white colours into Data.Colour? Which is better form making a > colour: (sRGB r g b) or (sRGB (r,g,b))? > > Bug reports and any patches are also welcome. Be warned, I haven't > extensively tested this library yet. > I think it would be nice to have conversion functions for wxHaskell and the like, to convert between the different color representations. -- Regards, Henk-Jan van Tuyl -- http://functor.bamikanarie.com http://Van.Tuyl.eu/ --

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Re: [Haskell] ANNOUNCE: colour 0.0.0
by roconnor＠theorem.ca 25 Oct '08

25 Oct '08

On Fri, 24 Oct 2008, Sebastian Sylvan wrote: > Another useful predefined space which I didn't see is the YCoCg space, which is used in lots of > compression schemes (like H.264 IIRC). YCoCg, like HLS and HSV, seems to not really be a colour space because it isn't well specified. A transformation is given from some unknown RGB space. Perhaps I should make a datatype for unknown RGB triple, and create HLS HSV, and YCoCg transforms from this type. I can have toRGB709 and toSRGB take and return this unknown RGB triple type. This would suggest changing sRGB and rgb709 from the type sRGB :: a -> a -> a -> Colour a to sRGB :: RGB a -> Colour a so the code "sRGB r g b" becomes "sRGB (RGB r g b)". That doesn't seem very nice. Also, I could add phantom type annotations to the RGB triple type, allowing it to be labeled as linear, or nonlinear, or other information. -- Russell O'Connor <http://r6.ca/> ``All talk about `theft,''' the general counsel of the American Graphophone Company wrote, ``is the merest claptrap, for there exists no property in ideas musical, literary or artistic, except as defined by statute.''

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ANN: Lambdabot 4.2.2
by Gwern Branwen 25 Oct '08

25 Oct '08

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 A quick note. Today was released the 4.2.2 version of the IRC bot Lambdabot. You can find it at <http://hackage.haskell.org/cgi-bin/hackage-scripts/package/lambdabot-4.2.2>, and the usual Darcs repository <http://code.haskell.org/lambdabot>. What is interesting about this release? * Less buggy. A few UTF-related bugs were fixed, some formatting bugs, etc. * Updated state (ever more @quote goodness) * New feature: Lambdabot can now be run in arbitrary directories like ~/. Before, one *had* to run in the darcs-gotten directory - Lambdabot had all sorts of hardwired constants like "./State/quotes" in it. Now the situation is such: Lambdabot first looks for a ./State/ and so on; if it finds a populated State/, it will read and write those files just like an old Lambdabot would. However, if State/ is not there, then Lambdabot will look for ~/.lambdabot/, and use the State/ hierarchy inside it, just as normal. Should there be neither a local directory, nor a ~/ directory, then Lambdabot will ask Cabal where all its State files were stuffed (presumably in /usr/share or wherever), and copy them to ~/.lambdabot, and try the sequence again. The upshot is that now you can be in ~/ or ~/bin/xmonad or anywhere, and type 'lambdabot' for a quick session. * No more dependency on BotPP and crazy pre-build processing, thanks to some Template Haskell contributed by sjanssen * those changes included in this classification * innumerable ones; * those drawn with a very fine camel's-hair brush; * etcetera * just broken the flower vase; * those that at a distance resemble flies - -- gwern -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) Comment: http://getfiregpg.org iEYEAREKAAYFAkkCfX4ACgkQvpDo5Pfl1oK/kQCeJAqdv4yNerXrhBQKaHjQlXWJ F4QAoJztlzLTFwHkFR5eRcrkFFmTcMe+ =lELz -----END PGP SIGNATURE-----

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ANN: Autoproc Change of Maintainer (if you use procmail you should read this)
by Jason Dagit 25 Oct '08

25 Oct '08

What is autoproc? ------------------------- Tired writing procmail recipes by hand? You're in luck! Autoproc makes it quick and easy for Haskell programmers to make procmail recipes by using an embedded domain specific language. Once your recipes type check and compile you simply run autoproc and it generates the corresponding procmail recipe on your screen. If you like the results, store it in ~/.procmailrc and enjoy! What's with this announcement? ------------------------------------------- I created autoproc a few years ago, but in that time I've farmed out my email to gmail and I'm no longer using procmail. In the meantime, Gwern Branwen has contributed nice features to the project to make it friendlier to use, cabalization and so on. With his permission, I am now declaring him the official maintainer and dictator for life. Long live Autoproc! Long live Gwern Branwen! Find it on Hackage: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/autoproc Find it on code.haskell.org: darcs get http://code.haskell.org/autoproc Note: We're using a darcs2 format repository, so to get the development version you'll need darcs 2.0 or newer. Thanks and enjoy your day! Jason

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The Haskell type inference feature I'd really like to see
by Dan Piponi 24 Oct '08

24 Oct '08

I'd like to be able to write something like > map zipWith ([1,2,3] >>= printMyInferredType) and have the compiler treat 'printMyInferredType' as undefined, but also produce the side effect of printing out its inferred type. What's the easiest way to simulate this with what we have now? -- Dan

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Re: [Haskell-cafe] Crash!
by Andrew Coppin 24 Oct '08

24 Oct '08

Thomas DuBuisson wrote: > So if you have such a specific portion of the code you think is to > blame, perhaps you could simple comment that out (return () instead of > write the file) and see if it crashes? I understand people avoidance > of brute force guess problem-compile-test cycles, but it seems you > have good evidence supporting this guess. Yeah, I can try different optimisation levels and so forth. I'm actually wondering if my code is writing off the end of an array and this "just happens" to hit some data structure used by GTK+? (In which case, minute changes in linkage, etc., would disturb the bug.) Does anybody know of any tools for definitely pinning down stuff like this? Surely C programmers have their code crash several hundred times a day due to bugs like this... > Also, be sure the thunks are evaluated - if the writing of the file > is what is forcing the evaluation (and thus triggering the condition) > then you need to separate these two cases. That's the fun part about Haskell, eh? ;-) However, in this instance, there's that much explicit mutation in the I/O monad on unboxed (and therefore strict) arrays that I'm pretty sure that isn't the problem. By the time the save-PNG function is called, the data already exists in the address space managed by GTK+. It has to, or GTK+ wouldn't be able to save it. Unless my *pure* code is somehow generating an access violation - which would surely indicate an actual compiler *bug*... (This seems laughably unlikely.)

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universal algebra "support" in Haskell?
by Galchin, Vasili 24 Oct '08

24 Oct '08

Hello, I see that there is a "Monoid" class from Data.Monoid. What other algebras like Group, Ring, etc. have support in Haskell? Thanks, Vasili

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RE: [Haskell] Current XML libraries status
by Mitchell, Neil 24 Oct '08

24 Oct '08

Redirected to haskell-cafe, since that's where all discussions should go (haskell = announcments only) > > Does some one have made performance tests on the different XML > > libraries for Haskell? I have a 20MB xml file that I want > to read. I > > remember from my earlier experiments (years ago) that all libraries > > were too slow and were consuming too much memory. > > For my XML needs, I ended up just using the TagSoup library > to extract the parts I wanted. At least this allows lazy > processing of large files (a typical file is in the 1 to 4 GB range). > > Performance is acceptable, and Neil is rumored to have a plan > to improve it further. I have a plan, I have the pseudo-code, and I have the notes. I currently don't have the time - but hopefully I'll find the time at some point. Thanks Nmeil ============================================================================== Please access the attached hyperlink for an important electronic communications disclaimer: http://www.credit-suisse.com/legal/en/disclaimer_email_ib.html ==============================================================================

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darcs hacking sprint TOMORROW!
by Eric Kow 24 Oct '08

24 Oct '08

Hi all, Just pointing out that the darcs hacking sprint is taking place tomorrow (Saturday and Sunday 25-26 October)! Our Brighton and Portland venues are still open, so if you are thinking of dropping by, let us know :-) http://wiki.darcs.net/index.html/Sprints Cheers, -- Eric Kow <http://www.nltg.brighton.ac.uk/home/Eric.Kow> PGP Key ID: 08AC04F9

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distributed systems reading group
by Jason Dusek 24 Oct '08

24 Oct '08

I'm looking for good reading group for distributed systems. I've worked through a number of papers on my own and would like to work out some ideas with other folks who have an interest. I've read a little bit of Lynch, a bit more of Lamport and some of Chandra's work, as well as numerous slides, &c. * The impossibility results are sobering, but always leave a way out -- they make some assumption that one can dispense with in practice (for example, that processes start with different values). * The possibility results generally make untenable assumptions -- for example, that there is no link failure. I appreciate that this is not a matter of direct interest to the list, but I expect to find interested people here. -- _jsn

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