October 2008 - Haskell-Cafe

RE: [Haskell] Making 'Super Nario Bros.' in Haskell‏
by Eli Ford 30 Oct '08

30 Oct '08

That’s great -- easy to follow, even though I can’t read the comments. ^^ It’s not possible for actors to ‘watch’ each other in this system, correct? For instance, if one actor holds a reference to another, it will keep that old version of the actor alive, but it won’t see when the actor moves. This game doesn’t seem to need actors that watch each other, but it’s very common in games. I’ve been using IORefs for that purpose, but I like how pure the Mario game is. Is there a better way than IORefs? ________________________________ From: haskell-bounces(a)haskell.org [mailto:haskell-bounces@haskell.org] On Behalf Of Korcan Hussein Sent: Wednesday, October 29, 2008 4:57 PM To: haskell(a)haskell.org Subject: [Haskell] Making 'Super Nario Bros.' in Haskell‏ Hi I haven't seen this posted any where so I'm sorry in advance if this has been mentioned already but I came across this recent video on youtube: http://uk.youtube.com/watch?v=gVLFGQGRsDw it's a mario clone written in haskell with a link to source code repository (http://svn.coderepos.org/share/lang/haskell/nario/) I thought that it maybe useful to some people. Trustworthiness: Vendor reliability: Privacy: Child safety: ________________________________ For the best free wallpapers from MSN Click here! <http://wallpapers.msn.com/?ocid=%5bB001MSN42A0716B%5d>

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Hugs GraphicsUtils "legacy" code
by Galchin, Vasili 30 Oct '08

30 Oct '08

Hello, What is the suggested migration path from the Hugs GraphicsUtils to contemporary Haskell?? Thanks, Vasili

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[Somewhat OT] Speed
by Andrew Coppin 30 Oct '08

30 Oct '08

Hi guys. This isn't specifically to do with Haskell, but... does anybody have any idea roughly how fast various CPU operations are? For example, is integer arithmetic faster or slower than floating-point? Is addition faster or slower than multiplication? How much slower are the trigonometric functions? etc. Does using 8-bit integers make arithmetic any faster than using wider values? Does anybody have a good resource for this kind of information?

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Problems with Windows
by John Van Enk 29 Oct '08

29 Oct '08

Hello All, I'm trying to reinstall network-2.2.0.0 against Parsec 3 in Windows. Well, this is really hard/impossible to do. Here's what I've done so far: 1) After bashing my face against my desk for a while, I got cabal-install installed in windows. 2) cabal install network --reinstall 3) This freaks out because I don't have hsc2hs installed, but it doesn't tell me that, it just complains about something having to do with sizeof. 4) I figure out that I need hsc2hs installed, and i put cabal-install to use fetching it for me. 5) cabal-install fails because hsc2hs needs the process and directory packages, but they aren't exposed by the cabal file (at least in the version sitting on hackage, I assume this is the right one to use). 6) I give up on using cabal-install to get hsc2hs, so i download the targz for hsc2hs directly. 7) I fix the .cabal file to include process and directory 8) runhaskell Setup configure: >runhaskell Setup configure Configuring hsc2hs-0.67.20061107... Warning: No 'build-type' specified. If you do not need a custom Setup.hs or ./configure script then use 'build-type: Simple'. 9) runhaskell Setup build: Everything works fine. 10) runhaskell Setup install: Everything works fine. 11) Go back to try and install network-2.2.0.0 again with cabal-install. 12) Gets past the sizeof/hsc2hs errors, but then chokes on spaces in build path names: Preprocessing library network-2.2.0.0... gcc.exe: Files\Haskell\parsec-2.1.0.1\ghc-6.8.3: No such file or directory linking dist\build\Network\BSD_hsc_make.o failed command was: C:\ghc\ghc-6.8.3\gcc.exe -BC:\ghc\ghc-6.8.3\gcc-lib -IC:\ghc\ghc-6.8.3\include\mingw -LC:\Program Files\Haskell\parsec-2.1.0.1\ghc-6.8.3 -LC:\ghc\ghc-6.8.3/lib\base-3.0.2.0 -lwsock32 -lmsvcrt -lkernel32 -luser32 -lshell32 -LC:\ghc\ghc-6.8.3 -LC:\ghc\ghc-6.8.3/gcc-lib -lm -lgmp -lwsock32 dist\build\Network\BSD_hsc_make.o -o dist\build\Network\BSD_hsc_make.exe cabal: Error: some packages failed to install: network-2.2.0.0 failed during the building phase. The exception was:exit: ExitFailure 1 13) And this is where I finally gave up and came here. Does any one have any insight into: 1) Why cabal doesn't check for hsc2hs during a configure 2) How I can rebuild network-2.2.0.0 on my Windows box without sacrificing a goat to Bill Gates/GHC Gods? Thanks. /jve

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Re: [Haskell] How to get the binary respentation of the Int/Double.
by Ryan Ingram 29 Oct '08

29 Oct '08

Actually, this is a good question, at least as relating to floating point values. Is there a primitive to view the machine representation of floats? I'm thinking of functions like: reinterpretFloatAsWord :: Float -> Word32 reinterpretWordAsFloat :: Word32 -> Float reinterpretDoubleAsWord :: Double -> Word64 reinterpretWordAsDouble :: Word64 -> Double There are decodeFloat and encodeFloat in the RealFloat class, but these seem to be a bit heavy for inner-loop usage, especially when you are just going to paste the values back together into a word immediately anyways. Are the precision of Float and Double specified by the standard? There's actually lots of nice tricks you can do with these functions; for example, if you know you have a floating point value between 0 and 2^23-1, you can convert it to integer with a floating point add and an integer mask: > magic = 0x00800000 :: Float -- 2^23 > magicMask = 0x007fffff :: Word32 -- 2^23 - 1 > fastFloatToInt23 :: Float -> Word32 > fastFloatToInt23 x = reinterpretFloatAsWord (x + magic) .&. magicMask The add sets the exponent of the float to +23 and arranges it so the low bit of the float corresponds to "1", rounding if necessary. Then you can interpret the result as an integer and mask off the exponent and sign bit from the float, leaving you with just the integer value. This relies on the representation of IEEE single-precision floats, of course. These sorts of tricks come have in handy when working on graphics code; often I've found myself wanting to index into an array with the nearest value after some floating point computation. Texture mapping hardware does this conversion all the time, for example, and sometimes it's useful to emulate that behavior in software. -- ryan On Tue, Oct 28, 2008 at 10:08 AM, Brandon S. Allbery KF8NH <allbery(a)ece.cmu.edu> wrote: > On 2008 Oct 28, at 10:38, haihualin wrote: >> >> I am wondering how to get the binary respentation of the Int/Double. >> So I can save the integer as the binary data so that the C program can >> read it from the file. > > > The Binary package on Hackage (http://hackage.haskell.org) allows you to > serialize Haskell data in any form including C-compatible binary output. > > -- > brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allbery(a)kf8nh.com > system administrator [openafs,heimdal,too many hats] allbery(a)ece.cmu.edu > electrical and computer engineering, carnegie mellon university KF8NH > > > _______________________________________________ > Haskell mailing list > Haskell(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell >

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How to use lib compat-base3 in ghc 6.10?
by Magicloud 29 Oct '08

29 Oct '08

Hi, Xmonad needs Data.Generics from base3. And I found out that there is a "compat-base3" in ghc 6.10, which has Data.Generics. But `ghc -v` reports that base-3.0.3.0 is hidden. So I wonder how could I compile Xmonad with ghc 6.10? Thanks.

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Re: [darcs-users] Poll: Do you need to be able to build darcs from source on GHC 6.6?
by Matthias Kilian 29 Oct '08

29 Oct '08

On Wed, Oct 29, 2008 at 12:11:22PM +1100, Trent W. Buck wrote: > To my mind, the benefit is negligible, because: > > Then we still have OpenBSD users. > > means we can't drop GHC 6.6 support. Also, note that Lenny has 6.8, > and it is scheduled to become stable Real Soon Now. Ok, it all depends on when the next release of darcs will be ready and when I (or someone else) gets ghc-6.8 or 6.10 done for OpenBSD (yes, I'm working on this, even after I dropped maintainership from our ghc port). I *hope* to get a working ghc-6.10 port for OpenBSD to the end of this year, and I guess that's a short enough timeline that darcs could drop 6.6 support if it's really necessary. Ciao, Kili

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Fwd: [Haskell-cafe] ANNOUNCE: Data.TCache 0.5.1
by Alberto G. Corona 29 Oct '08

29 Oct '08

---------- Forwarded message ---------- From: Alberto G. Corona <agocorona(a)gmail.com> Date: 2008/10/29 Subject: Re: [Haskell-cafe] ANNOUNCE: Data.TCache 0.5.1 To: Joachim Breitner <mail(a)joachim-breitner.de> I developed it in 2006. At this time I think that Happs did not used STM. I do not know Happs.State very well. The main difference is that it is far far simple (only a handfull of methods exported) it is configurable and permit the full semantic of TVars without loosing content persistence. Also, the query is based on let´s say patterns. A pattern is a partilally filled object. enough to deduce the key. the interface is very natural. For example: withResources [ User{ name= "Alberto"} , Product{ id="Playstation"} buyIt where buyIt [Just user, Just product]= [user{due= due user +price product}, product{ stock= stock product -1]] buyIt _ = error "either the user or the product not found" Just prod <- getResource Product{ id="Playstation"} bla bla bla 2008/10/29 Joachim Breitner <mail(a)joachim-breitner.de> > Hi, > > Am Dienstag, den 28.10.2008, 23:26 +0100 schrieb Alberto G. Corona : > > Data.Tcache is a transactional cache with configurable persistence. It > > tries to simulate Hibernate for Java or Rails for Ruby. The main > > difference is that transactions are done in memory trough STM. There > > are transactional cache implementations for some J2EE servers like > > JBOSS. > > > > TCache uses STM . It can atomically apply a function to a list of > > cached objects. The resulting objects go back to the cache > > (withResources). It also can retrieve these objects (getResources). > > Persistence can be syncronous (syncCache) or asyncronous, wtih > > configurable time between cache writes and configurable cache > > clearance strategy. the size of the cache can be configured too . All > > of this can be done trough clearSyncCacheProc. Even the TVar variables > > can be accessed directly (getTVar) to acceess all the semantic of > > atomic blocks while maintaining the persistence of the TVar updates. > > > > Persistence can be defined for each object.: Each object must have a > > defined key, a default filename path (if applicable). Persistence is > > pre-defined in files, but the readResource writeResource and > > delResource methods can be redefined to persist in databases or > > whatever. > > Interesting. Without much deep knowledge, this sounds similar to > HAppS.State. Where are the differences? > > Greetings, > Joachim > > -- > Joachim "nomeata" Breitner > mail: mail(a)joachim-breitner.de | ICQ# 74513189 | GPG-Key: 4743206C > JID: nomeata(a)joachim-breitner.de | http://www.joachim-breitner.de/ > Debian Developer: nomeata(a)debian.org > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > >

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Re: Poll: Do you need to be able to build darcs from source on GHC 6.6?
by trentbuck＠gmail.com 28 Oct '08

28 Oct '08

"Trent W. Buck" <trentbuck(a)gmail.com> writes: > On Wed, Oct 29, 2008 at 12:39:28PM +0900, Stephen J. Turnbull wrote: >> Trent W. Buck writes: >> >> > In an ideal world, we just make sure it builds with the latest tools, >> > and let the users of stable distros worry about telling us if it >> > breaks against whatever versions they care about. >> >> This is very disappointing coming from (some) developers of *version >> control software*! You'd think they, of all software developers, >> would be sympathetic to the need to, well, control versions! > > Let me clarify that the above are my *personal* opinions, and I'm not > really involved in the Darcs Haskell code -- just the surrounding > build and documentation infrastructure. > > I'm speaking more from my role as a Debian maintainer and user than as > a member of the Darcs comunity. Actually, even more than that I'm speaking as someone who for years tried to keep shell scripts portable and POSIX clean and working even on ten-year-old versions of Solaris... before deciding that I was investing waaaaay too much time testing on those systems considering approximately zero of my users ran them. So I said "fuck it, I'll use bash and assume GNU coreutils, and if it breaks on someone's system, they'll tell me."

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Re: [darcs-users] Poll: Do you need to be able to build darcs from source on GHC 6.6?
by David Roundy 28 Oct '08

28 Oct '08

On Wed, Oct 29, 2008 at 12:11:22PM +1100, Trent W. Buck wrote: > > Thus I think the version/upgrade matrix is handy so we can > > plan/schedule when it is safe to drop support. > > In an ideal world, we just make sure it builds with the latest tools, > and let the users of stable distros worry about telling us if it > breaks against whatever versions they care about. No, in the idea world we'd try to be supportive of our contributors and maintainers by not requiring that they install the latest tools. -- David Roundy http://www.darcs.net

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