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GHC 6.6.1 and SELinux issues
by Alexander Vodomerov 29 Aug '07

29 Aug '07

Hello! Does anybody here uses GHC on Linux with SELinux turned on? I've just installed SELinux and run into GHC/SELinux incompatibility. It seems that the similar problem was reported some time ago and was fixed in 6.4.3. However, I use 6.6.1 and the problem is still here. $ ghc ghc-6.6.1: internal error: getMBlock: mmap: Permission denied (GHC version 6.6.1 for i386_unknown_linux) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug Exactly the same bug is appearing on x86_64 architecture. Much more details is available at http://hackage.haskell.org/trac/ghc/ticket/738 Any ideas? With best regards, Alexander. PS. Is it possible to turn on global allow_execmem boolean in SELinux policy, thus enabling executable memory mapping. This solves the problem. However, this is major drawback for system security and should be avoided at any cost.

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Wildly off-topic
by Andrew Coppin 29 Aug '07

29 Aug '07

http://importantshock.wordpress.com/2007/08/21/haskell-curry-yes-i-dated-hi… (Actually, you hardly need to click that. The URL says it all...)

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[Off Topic Amusement] Lylle Lovett lyrics
by David Pollak 29 Aug '07

29 Aug '07

http://www.lyricsdepot.com/lyle-lovett/west-texas-highway.html -- lift, the fast, powerful, easy web framework http://liftweb.net

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[ANN] An efficient lazy suffix tree library
by Bryan O'Sullivan 28 Aug '07

28 Aug '07

I just posted a library named suffixtree to Hackage. http://www.serpentine.com/software/suffixtree/ It implements Giegerich and Kurtz's lazy construction algorithm, with a few tweaks for better performance and resource usage. API docs: http://darcs.serpentine.com/suffixtree/dist/doc/html/Data-SuffixTree.html I've tested it on multi-megabyte input strings. <b

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"quoting" in Haskell
by Peter Verswyvelen 28 Aug '07

28 Aug '07

In Scheme, on can "quote" code, so that it becomes data. Microsoft's F# and C# 3.0 also have something similar that turns code into "expression trees". The latter is used extensively in LINQ which translates plain C# code into SQL code or any other code at runtime (this idea came from FP I heared) I can't find something similar for Haskell? Maybe I am looking at the wrong places? In Haskell, I know one can use a data constructor as a function (as in (map Just [1..3])), but a function cannot be turned into a data constructor (= "quoting"), can it? Now this is all really fuzzy for a newbie like me, because aren't all functions initially just data constructors waiting to be evaluated in a lazy language? I'm actually looking for something like (loose terminilogy follows) "context-based-semi-quoting". The idea is to only quote a set of functions, while evaluating all the others. For example, in the code 1 `add` 2 `mul` 3 where add = (+) mul = (*) I want to write something like selectiveQuote [add] (1 `add` 2 `mul` 3) which would result in an expression tree like add / \ 1 6 So the `mul` is not quoted because it is not part of the "context" = [add] Maybe this is just impossible, I did not dig deep into this. Thanks, Peter

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No Enum nor Ix instance on Graphics.UI.GLUT.Key
by Peter Verswyvelen 28 Aug '07

28 Aug '07

I want to make an array using GLUT.Key as an index, but it is not an instance of Enum nor Ix Of course, I can make it an instance myself, but I guess it would be easier to do so in the library? Cheers, Peter

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Geometry
by Tony Morris 28 Aug '07

28 Aug '07

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 I went camping on the weekend and a friend of mine who is a builder asked me many questions on geometry as they apply to his every day work - - most of which I could answer. However, there was one that I couldn't and I am having trouble googling a solution (for lack of keywords?). I'm hoping a fellow Haskeller could help me out (in Haskell of course). The problem is finding the unknown x from the two knowns a and b in the given image below (excuse my Microsoft Paintbrush skills). I may have misunderstood his problem (we were drawing in dirt) and actually, it is the straight line between the two points on the circumference that are known and not the specified 'b', but I figure I could derive one solution from another if I have misunderstood him. Here is my image: http://tinyurl.com/2kgsjy Thanks for any tips or keywords with which to google! - -- Tony Morris http://tmorris.net/ -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFG0iM6mnpgrYe6r60RAqfDAJ4gFAdr7zP1ehLl8H2MaCzCNfAvhQCgmL8D 4nrxrK13O9EBNv/ojPIMJXI= =eaxX -----END PGP SIGNATURE-----

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[ANN] pcap 0.3.1, for user-level network packet capture
by Bryan O'Sullivan 28 Aug '07

28 Aug '07

I've taken over maintenance of the pcap library (an interface to libpcap, for user-level network packet capture), and released a new version. Home page: http://www.serpentine.com/software/pcap/ API docs: http://darcs.serpentine.com/pcap/dist/doc/html/pcap/ Download: http://hackage.haskell.org/packages/archive/pcap/ darcs repo: darcs get http://darcs.serpentine.com/pcap/ Thanks are due to Gregory Wright for originally writing the package, and Dominic Steinitz and Nick Burlett for their respective maintenance efforts. <b

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Re: [Haskell-cafe] Norvig's Sudoku Solver in Haskell
by manu 28 Aug '07

28 Aug '07

From: Daniel Fischer > Thought it was something like that. > Must check whether that beats Norvig's constraint propagation. it does ! on my machine : Jon Harrop's : 12.5 sec and Norvig's : 15 sec Manu

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Newbie terminology for partial application
by Peter Verswyvelen 28 Aug '07

28 Aug '07

A while ago I confused "currying" with "partial application", which was pointed out by members of this community, and the wiki pages got adapted so that newbies like me don't make the same mistake twice ;) That's great. Anyway, at the risk of making mistakes again, I'm looking for good terminilogy when talking about "partial application". For example: -- uncurried form *f (x,y)* = -- whatever -- curried form *g x y *= f (x,y) -- partial application *h x *= g x But when writing text documents, I guess it is common to say "/g is curried/", but is it also common to say /"g is partially applied"? /The latter sounds silly to a non-native speaker like myself... Or shouldn't it be? / /And what is "application"? I guess it means that (g x y) is internally translated to ((g $ x) $ y) which is translated into (apply (apply g x) y) where apply is a primitive function? Thanks, Peter PS: sorry for the poor English! / /

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