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Problem with Haskell Platform website
by Dietrich Epp 24 Mar '10

24 Mar '10

There's a problem with the Haskell Platform website. I'm posting the message here because I gave up looking for contact information for the site, maybe someone here can forward the message or tell me who to forward it to? The specific page is http://hackage.haskell.org/platform/mac.html Being one of the few who still use the PPC architecture, I expect to have to build my own packages from source. Imagine my surprise when the Haskell platform uses the "Universal Binary" logo on the Mac download. Nowhere on the Mac download page does it specify an architecture. However, the binary is i386 only and not PPC. So I just wasted time downloading something I can't install on my computer. This page shows the "Universal Binary" logo: http://hackage.haskell.org/platform/ Here is Apple's "Universal Binary" page, which describes what the logo means: http://www.apple.com/universal/ It would be nice to get rid of the "Universal Binary" logo and to mark the packages as i386. --Dietrich Epp

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Syntax programming with lexemes rather than trees?
by Max Rabkin 24 Mar '10

24 Mar '10

[Sorry for the accidental off-list reply, Neil] On Tue, Mar 23, 2010 at 10:43 PM, Neil Mitchell <ndmitchell(a)gmail.com> wrote: > It actually sounds like your representation has structure, but you > dislike structure because it's hard to work with. It seems to me like the data has structure, but that data is not treelike! Is a performance a collection of measures or a collection of instruments? A tree-like structure makes you choose, but in truth it is both. I'm not sure I've seen a good solution to this kind of problem in FP. --Max

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Are there any web server framework ?
by zaxis 24 Mar '10

24 Mar '10

Erlang has yaws (http://yaws.hyber.org/) Scala has lift (http://liftweb.net/) Python has django (http://www.djangoproject.com/) Ruby has rails (http://rubyonrails.org/) How about haskell ? Is there any similar framework, which should be steady, powerful and easy to use, in haskell ? Sincerely! ----- fac n = let { f = foldr (*) 1 [1..n] } in f -- View this message in context: http://old.nabble.com/Are-there-any-web-server-framework---tp27926433p27926… Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.

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Cabal Compiler Flag Problem
by Ben Derrett 24 Mar '10

24 Mar '10

Hi, I'm trying to install the Haskell cgi module, as per here http://passingcuriosity.com/2009/haskell-fastcgi-with-apache/. When I type cabal install cgi, I get the following error (on a Fedora instance): cabal install cgi Resolving dependencies... Configuring MonadCatchIO-mtl-0.3.0.0... Preprocessing library MonadCatchIO-mtl-0.3.0.0... Building MonadCatchIO-mtl-0.3.0.0... [1 of 1] Compiling Control.Monad.CatchIO ( Control/Monad/CatchIO.hs, dist/build/Control/Monad/CatchIO.o ) Control/Monad/CatchIO.hs:146:34: Illegal signature in pattern: E.SomeException Use -XPatternSignatures to permit it cabal: Error: some packages failed to install: MonadCatchIO-mtl-0.3.0.0 failed during the building phase. The exception was: exit: ExitFailure 1 cgi-3001.1.8 depends on MonadCatchIO-mtl-0.3.0.0 which failed to install. So, I modified my /root/.cabal/config with: -- flags: -XPatternSignatures This doesn't seem to resolve the problem. What do I need to do to change the compiler flags? Thanks, Ben

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installing Network on windows
by gladstein＠gladstein.com 24 Mar '10

24 Mar '10

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Timeouts that don't cause data growth.
by David Leimbach 24 Mar '10

24 Mar '10

Trying to understand why the code here: http://moonpatio.com/fastcgi/hpaste.fcgi/view?id=8823#a8823 exhausts memory. I need to have timeouts in a program I'm writing that will run an interactive polling session of some remote resources, and know when to give up and handle that error. Unfortunately this code dies pretty quickly and produces an -hc graph like the one attached. It seems that System.Timeout can't be used for this. I should note that if the code is changed to use an inifnite timeout (-1) that this problem doesn't occur. Is this a bug in System.Timeout, or is there something I should be doing to keep the data size down? Dave

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ANNOUNCE: Bravo-0.1.0
by Matthias Reisner 24 Mar '10

24 Mar '10

Hello, I'm pleased to announce the first release of Bravo, a static text template generation library, on Hackage: http://hackage.haskell.org/package/Bravo. Bravo is a text template library that provides parsing and generation of templates at compile time. Templates can be read from strings or files and for each a new record data type is created, allowing convenient access to all template variables in a type-safe manner. Since all templates are processed at compile time, no extra file access or error handling at runtime is necessary. Bravo is inspired by the PHP template engine Smarty and the Haskell template library chunks. Compared to chunks, Bravo provides additional features like conditional template evaluation, embedding of Haskell expressions and customized data type generation. I'm going to add further information to the HaskellWiki page (http://www.haskell.org/haskellwiki/Bravo) later. Bravo is still highly experimental and not well-tested, so bug reports and additional feedback are very welcome. I'd also like to hear if you feel the package dependencies are to restrictive. Regards, Matthias Reisner

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Bytestrings and [Char]
by Johann Höchtl 23 Mar '10

23 Mar '10

Hello, I was recentyl playing with Haskell (GHC that is) IO and text processing. Bytestrings and Lazy Bytestrings allow for fast and memory eficient string (well, bytestring) handling, yet a lot of libraries do not support them (yet) Given the incredibly inneficient memory representation of [Char] (16 bytes? per cell) I wonder wheather String should default to lazy batestring altogether instead of [Char]. The levenshtein distance as is on hackage uses e.g. String ([Char]) and as such is unneccessarily slow. My question or discussion point: Why not depreciate [Char] altogether and favour of lazy Bytestrings? Regards, Johann

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Fwd: [Haskell-cafe] Bytestrings and [Char]
by Alberto G. Corona 23 Mar '10

23 Mar '10

Just a dream: -separate interface and implementation for all containers, via type classes -develop, by genetic programming techniques + quickcheck, a system that find the best container implementation for a particular program. Is that suitable for a Google Summer of Code project? 2010/3/23 Alberto G. Corona <agocorona(a)gmail.com> The question can be generalized via type classes: Is there any common set of > primitives encapsulated into a single type class that has instances for > Strings (Data.List) ByteStrings, Data.Text, Lazy bytestrings, Arrays, > vectors and wathever container that can store an boxed, unboxed, packed > unpacked sequence of wathever including chars? All of them have folds, > heads, tails and a lot of common functions with the same name, but since > there is not a single type class, the library programmer can not abstract > his code when it is possible, so the library user can chose the particular > instance for his particular problem. > > 2010/3/23 Johann Höchtl <johann.hoechtl(a)gmail.com> > > On 22.03.2010 14:15, Ivan Miljenovic wrote: >> >>> On 23 March 2010 00:10, Johan Tibell<johan.tibell(a)gmail.com> wrote: >>> >>> >>>> A sequence of bytes is not the same thing as a sequence of Unicode >>>> code points. If you want to replace String by something more efficient >>>> have a look at Data.Text. >>>> >>>> >>> Though Data.Text still has the disadvantage of not being as nice to >>> deal with as String, since you can't pattern match on it, etc. >>> >>> Whilst it may degrade performance, treating String as a list of >>> characters rather than an array provides you with greater flexibility >>> of how to deal with it. >>> >>> >>> >> But doesn't this basically mean sacrifice performance / applicability for >> algorithmic beauty? Sure, pattern match comes in handy, but in the case of >> strings at a high price >> >> >> _______________________________________________ >> Haskell-Cafe mailing list >> Haskell-Cafe(a)haskell.org >> http://www.haskell.org/mailman/listinfo/haskell-cafe >> > >

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Re: [Haskell-cafe] Bytestrings and [Char]
by Iustin Pop 23 Mar '10

23 Mar '10

On Tue, Mar 23, 2010 at 05:53:00PM +0000, Vincent Hanquez wrote: > On 23/03/10 17:11, Iustin Pop wrote: > >Data.ByteString.Lazy (bytestring readFile + length) -< 10 miliseconds, > >incorrect length (as expected). > > > >Data.ByteString.Lazy.UTF8 (system readFile + fromString + length) - 11 > >seconds, correct length. > > Why would you use system readFile and not bytestring readFile in the > second case ? > > using the later i got a ~48x slowdown, not a >1100x slowdown, and > the length is correct too. Hmm… because I didn't think of that :) iustin

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