- Haskell-Cafe - Haskell.org

map/reduce example
by Bulat Ziganshin 07 Jan '08

07 Jan '08

Hello Haskell-Cafe, i've written small program which demonstrates how map/reduce may be implemented in Haskell. it counts amount of words in file, splitting it into 64kb blocks processed by two threads. their results are combined by another two threads. how it may be made better? in particular, is it strict in values send over channels? {-# LANGUAGE BangPatterns #-} import Control.Concurrent import Control.Concurrent.Chan import Control.Monad import Data.IORef import Data.ByteString.Char8 as B hiding (length) import System.Environment import System.IO main = do (file:_) <- getArgs h <- openBinaryFile file ReadMode map <- newChan reduce <- newChan result <- newChan replicateM_ 2 (forkIO$ mapThread map reduce) replicateM_ 2 (forkIO$ reduceThread reduce result) jobs <- new 0 untilM (hIsEOF h) $ do str <- B.hGet h 65536 writeChan map str jobs += 1 jobs' <- val jobs writeChan reduce (0,-jobs') res <- readChan result print res mapThread map reduce = forever $ do str <- readChan map let !sum = length (B.words str) writeChan reduce (sum,1) reduceThread reduce result = forever $ do (sum1,n1) <- readChan reduce (sum2,n2) <- readChan reduce let (!sum,!n) = (sum1+sum2,n1+n2) case n of 0 -> writeChan result sum _ -> writeChan reduce (sum,n) untilM cond action = do deny <- cond unless deny $ do action untilM cond action forever action = action >> forever action infixl 0 =:, += new = newIORef val = readIORef a=:b = writeIORef a b a+=b = modifyIORef a (\a->a+b) -- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com

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Re: [Haskell-cafe] what does @ mean?.....
by Serge LE HUITOUZE 07 Jan '08

07 Jan '08

Jedaï wrote: > [...] > Yes, but in the second version, it has to reconstruct (S a) before > comparing it to "one" where in the first it could do the comparison > directly. In this cas there may be some optimisation involved that > negate this difference but in many case it can do a real performance > difference. > The "as-pattern" (@ means as) is both practical and performant in most cases. Chris wrote: > The first example takes apart the (Just n) and later reconstructs (Just n). > Unless the compiler is fairly clever, this will cause the new (Just n) to be a > new allocation instead of reusing the input value. The second form uses an I tend to believe that the '@' notation is mere syntactic sugar. Indeed, it seems to me that Haskell compilers need not to be very clever to share the identical sub-expressions, for one very simple reason implied by Haskell semantics: referential transparency. Am I right, or am I missing something? And, of course, I'm not saying that syntactic sugar is bad. As Alfonso noted, it saves some typing and avoids screwing up while trying to modify multiple occurrences of the same sub-expression. And, an even more important I think, a software engineering benefit: It emphasizes for the reader that we really are talking about the very same thing at two (or more) different places. --Serge No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.17.9/1198 - Release Date: 26/12/2007 17:26

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Software Tools in Haskell
by Gwern Branwen 07 Jan '08

07 Jan '08

On 2007.12.10 13:52:41 -0600, Tommy McGuire <mcguire(a)crsr.net> scribbled 1.7K characters: > In the "if anyone is interested,..." department.... > > For reasons that remain unclear, early this fall I started translating > Brian W. Kernighan and P.J. Plaugher's classic _Software Tools in Pascal_ > into Haskell. I have completed most of it, up to the second part of > chapter 8 which presents a proto-m4 preprocessor. I have the code online > including notes, comments, descriptions, and a few alternate approaches. > > Attractions include: > > * A fair gamut of the usual Unix suspects: proto-cat, proto-wc, proto-tr, > proto-compress, proto-ar, proto-grep, etc. > > * A usable editor, if you consider a de-featured ed-alike to be usable. > > * A simple monadic regular expression engine. > > * Zippers, Parsec, the State monad, the StateT monad transformer, and other > attempts to sully Computing Science's brightest jewels. > > * Lots and lots of really bad Haskell, including a fair bit that is a > direct translation of 30-year old Pascal (see xindex in translit, Ch. 2, if > you need to skip lunch). Programming really has advanced, you know. > > Anyway, the URL is: > http://www.crsr.net/Programming_Languages/SoftwareTools > > Questions and comments would be appreciated, especially suggestions for how > to make the code cleaner and more understandable. Flames and mockery are > welcome, too, but only if they're funny---remember, I've been staring at > Haskell, Pascal (plus my job-related Perl, CORBA, and C++) for a while; > there's no telling what my mental state is like. > > [I had intended to wait until I had the whole thing done to make this > announcement, but I recently moved and have not made much forward progress > since, other than putting what I had done online.] > > -- > Tommy M. McGuire Some of those really look like they could be simpler, like 'copy' - couldn't that simply be 'main = interact (id)'? Have you seen <http://haskell.org/haskellwiki/Simple_Unix_tools>? For example, 'charcount' could be a lot simpler - 'charcount = showln . length' would work, wouldn't it, for the core logic, and the whole thing might look like: > main = do (print . showln . length) =<< getContents Similarly wordcount could be a lot shorter, like 'wc_l = showln . length . lines' (showln is a convenience function: showln a = show a ++ "\n") I... I want to provide a one-liner for 'detab', but it looks impressively monstrous and I'm not sure I understand it. One final comment: as regards run-length encoding, there's a really neat way to do it. I wrote a little article on how to do it a while ago, so I guess I'll just paste it in here. :) --- Recently I was playing with and working on a clone of the old Gradius arcade games which was written in Haskell, Monadius <http://hackage.haskell.org/cgi-bin/hackage-scripts/package/Monadius-0.9>. Most of my changes were not particularly interesting (cleaning up, Cabalizing, fixing warnings, switching all Integers to Ints and so on), but in its Demo.hs, I found an interesting solution to an interesting problem which seems to be a good example of how Haskell's abstractions can really shine. So, suppose we have these data items, which are levels which are specified by a pair of numbers and then a long list of numbers, often very repetitious. Perhaps a particular level might be represented this way: > level1 = ((Int,Int),[Int]) > level1 = ((2,1),[0,0,0,0,0,0,0,0,0,0,0,0,8,8,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,73,73,73,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,69,69,69,69,69,69,65,17,17,17,17,17,17,17,17,17,17,17,17,17,25,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,1,1,1,1,1,1,1,1,1,1,9,9,9,1,1,1,1,1,1,1,1,1,1,1,1,1,65,65,65,65,65,65,1,1,1,1,1,1,1,1,33,33,1,1,1,1,33,33,33,33,33,33,33,33,33,33,33,33,33,33,33,33,33,33,33,33,33,33,33,33,49,49,49,49,33,33,33,1,1,1,1,1,1,1,9,9,9,1,1,1,1,1,1,1,1,1,33,33,33,33,1,1,1,1,1,1,1,1,1,9,9,1,1,1,1,1,33,33,33,33,33,33,33,33,33,33,33,33,33,33,33,33,33,33,33,33,33,33,33,33,1,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,81,81,81,81,81,81,81,81,81,81,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,17,1,1,1,1,1,1,1,17,17,17,17,17,17,17,17,17,17,17,1,1,1,1,1,1,1,1,1,1,1,1,17,17,17,1,1,1,1,1,1,1,1,1,1,1,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,97,33,33,33,33,37,5,69,69,65,65,65,65,65,65,67,67,67,67,67,67,67,67,67,75,75,75,75,75,75,75,75,75,75,75,75,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,3,3,3,3,3,3,3,3,3,3,3,3,3,11,11,3,3,3,3,3,3,3,3,3,3,11,3,3,3,3,3,3,3,3,3,3,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,3,3,3,3,3,3,3,3,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,3,3,3,3,3,3,3,67,67,67,67,67,67,3,3,3,67,67,3,3,3,3,3,67,67,67,67,67,67,67,67,67,67,3,3,3,3,3,3,67,67,67,67,67,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,11,11,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,35,35,35,35,35,3,3,3,35,35,35,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,35,35,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,19,19,19,19,19,19,19,51,51,51,51,51,51,51,51,51,51,51,51,51,51,51,51,51,51,51,51,51,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,43,43,43,43,43,43,43,43,43,43,43,43,43,43,43,11,11,11,11,11,43,43,43,43,43,43,43,43,35,35,35,35,35,35,35,35,3,3,3,35,35,35,35,35,35,35,35,35,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,35,35,35,35,35,35,35,35,35,35,35,35,35,3,3,3,35,35,35,35,35,35,35,35,35,35,35,3,3,3,3,3,35,35,35,35,35,35,35,35,35,3,3,3,3,35,35,35,35,35,35,3,3,3,3,35,35,35,35,35,3,3,3,3,3,3,3,3,3,3,3,3,3,19,19,19,19,19,19,19,19,19,19,19,19,19,19,3,3,3,3,19,19,19,19,3,3,3,3,3,3,19,19,19,19,3,3,3,3,3,3,3,19,19,19,19,19,3,3,3,3,3,3,3,3,19,19,19,19,19,19,19,19,83,83,83,83,83,67,67,67,3,3,19,19,19,19,19,19,19,19,19,19,19,19,83,83,83,83,83,19,19,19,19,19,19,19,19,19,19,19,19,19,19,19,19,19,83,83,83,83,83,83,83,83,83,19,19,3,3,3,3,3,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,75,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,43,35,35,35,35,3,3,3,3,3,3,3,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,3,3,19,19,19,19,19,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,19,19,19,19,19,19,3,3,3,3,3,3,3,3,67,67,67,67,67,67,83,83,83,83,83,83,83,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,19,19,19,19,19,19,19,19,19,51,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,35,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,35,35,35,35,35,35,35,35,35,35,35,35,35,35,3,3,3,3,3,3,3,35,35,43,43,43,43,43,43,43,43,43,43,43,11,11,11,11,11,11,3,3,3,3,3,3,3,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,67,3,3,3,3,3,3,3,35,35,35,35,35,35,35,35,35,35,35,35,35,43,43,43,43,43,11,11,11,11,11,11,11,3,3,67,67,67,67,67,83,19,19,3,3,67,67,67,67,67,67,67,67,67,67,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]) This is clearly a bad way of representing things. We could just scrap this representation as Ints completely and perhaps define it as > -- Assume that these datatypes are already defined and everything > level1 :: ((Geometry,Geometry),[Enemies]) > level1 = ((Tall,Narrow), > > [FlyEnemy,FlyEnemy,FlyEnemy,FlyEnemy,FlyEnemy,FlyEnemy,Shooter,PowerUp,Boss..]) > -- and so on But this representation, while certainly more symbolic, is still very repetitious. We need some way of expressing this more concisely, of, in short, *compressing* it. In this vein of thought, our first observation should be that we do not need to resort to Gzipping it or adding dependencies on fancy compression libraries or anything; there is a very obvious way to compress it already - the entire thing is practically just a series of repeated numbers. We should be able to replace the length enumeration of [0,0,0,0,0,0,0,0,0,0,0,0] with something simpler, say the number of repetition and what is to be repeated so that our entry would look like (12,0). This representation is definitely shorter and more importantly, easier to modify and not a constant. It is possible that there may be a performance benefit here, as we've gotten rid of a large constant that would have to be defined in the program itself and instead replaced it with a shorter function which evaluates to the same thing. So, what is the type of our decompressing function? Well, we need to turn a (Int,Int) into a [Int]; even better, we want to turn a whole list of (Int,Int)s into a single list of [Int]. Thus, our end goal is going to be a function of this type: > rleDecode :: [(Int,Int)] -> [Int] Let us tackle the single tuple example first. The second entry defines what we need, and the first entry defines how many we need. We could write a recursive function that takes the parameter, decreases the first entry by one, and cons on one example of the second entry. It could look like this: > rleRecursiveDecode :: (Int,Int) -> [Int] > rleRecursiveDecode (0,_) = [] > rleRecursiveDecode (n,b) = b : (rleRecursiveDecode (n-1,b)) But this really is not the best way to go. It is not necessarily easy to follow, and if there is one thing I have learned about Haskell programming, it is that the most obvious approach (in this case, primitive recursion) may not be the best way to go. This is code that could have as well been written in Scheme or something. It is complicated because we are trying to ensure that we generate an item for the list only at the exact moment we need to add it into the list; we are programming as if our language is strict, in other words. So, what is the lazy way of doing things? Infinite lists, of course. We create an infinite list containing only the second entry, and we merely take as many as the first entry says we need. Simple enough! > -- Infinite list of our item of interest. > reduplicate a = a:a > rleLazyDecode :: (Int,Int) -> [Int] > rleLazyDecode (n,b) = take n (reduplicate b) Now, reduplicate is a simple enough function to define, but it already has a definition in the standard libraries - 'cycle'. (I assume you know what 'take' is, but that is also fairly easy to define once you seen the need for it.) So: > rleLazyDecode (n,b) = take n (cycle b) Might as well remove the parentheses: > rleLazyDecode (n,b) = take n $ cycle b A satisfying, short, functional, and lazy one-liner. From here the definition of rleDecode is almost trivial: we extend it to a list of tuples by throwing in a map, and we turn the resulting list of lists into a single list by way of 'concat': > rleDecode ns = concat $ map rleLazyDecode ns We can tweak this further, as 'concat . map' is a common enough idiom that there is a shortcut: > rleDecode ns = concatMap rleLazyDecode ns Aw heck - make it points-free: > rleDecode = concatMap rleLazyDecode And substitute in the rleLazyDecode definition: > rleDecode = concatMap (\(n,b) -> take n $ cycle b) We could also write a version that omits the explicit lambda and naming of parameters by use of the helpful but somewhat esoteric 'uncurry' function; Uncurry takes apart the tuple. Tts type is: > uncurry :: (a -> b -> c) -> (a, b) -> c We can actually go even further into the realms of incomprehensibility. It turns out that lists are counter-intuitively a monad! This means we can use bind and all the rest of the operations defined by the Monad typeclass to operate on lists and other things. So we can write the bizarre (but short and effective) version of rleDecode that follows: > rleDecode = (uncurry replicate =<<) And we are done! We can now represent the first list like this: > d1 = ((2,1),d) > where d = rleDecode [(5, 3), (10, 67), (6, 3), (5, 67), (29, 3), (2, 11), (29, 3), (5, 35), (3, 3), (3, 35), (24, 3), (2, 35), (19, 3), (7, 19), (21, 51), (63, 35), (15, 43), (5, 11), (8, 43), (8, 35), (3, 3), (9, 35), (20, 3), (52, 67), (32, 3), (13, 35), (3, 3), (11, 35), (5, 3), (9, 35), (4, 3), (6, 35), (4, 3), (5, 35), (13, 3), (14, 19), (4, 3), (4, 19), (6, 3), (4, 19), (7, 3), (5, 19), (8, 3), (8, 19), (5, 83), (3, 67), (2, 3), (12, 19), (5, 83), (17, 19), (9, 83), (2, 19), (5, 3), (20, 67), (1, 75), (38, 11), (1, 43), (4, 35), (7, 3), (57, 67), (2, 3), (5, 19), (17, 3), (6, 19), (8, 3), (6, 67), (7, 83), (59, 3), (9, 19), (1, 51), (17, 35), (20, 3), (14, 35), (7, 3), (2, 35), (11, 43), (6, 11), (7, 3), (26, 67), (7, 3), (13, 35), (5, 43), (7, 11), (2, 3), (5, 67), (1, 83), (2, 19), (2, 3), (10, 67), (21, 3), (147, 0)] Much nicer, don't you think? And the best part is, we should be able to reuse this run-length decoding even if we replace the arbitrary numbers by more descriptive type constructors! (Many thanks to the good denizens of #haskell, and Don Stewart's blog entry on run-length encoding/decoding using Arrows <http://cgi.cse.unsw.edu.au/~dons/blog/2007/07>.) -- gwern

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Re: Haskell-Cafe Digest, Vol 53, Issue 2
by Jens Blanck 06 Jan '08

06 Jan '08

> The normal view taken by Haskellers is that the denotations of > > Haskell types are CPPOs. > > CPPO? > > > So: > > > > (1) Must be monotone > > (2) Must be continuous > > Could you please define what you mean by those terms > in this context? > > > (Needn't be strict, even though that messes up the resulting category > > substantially). > > I'm not convinced that the category is all that "messed up". > > The extra P would stand for "pointed" (has a least element, bottom), this is common in some communities. To me though, a cpo (complete partial order) is closed under directed suprema and the empty set is directed so bottom is already required. The category of cpos in not cartesian closed. For denotational semantics I believe the subcategory of Scott domains are what is usually considered. Continuous functions on cpos are by definition monotone and they respect directed suprema. Jens

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Newbie question related to list evaluation
by Sai Hemanth K 06 Jan '08

06 Jan '08

Hi, I am new to functional and lazy programming languages ( that's correct, my life has been pretty pathetic so far) and am not able to understand GHC's behaviour for a particular function. Can someone help me please? I am trying to write a function which would compare two strings (from reverse) and return the position of first mismatch. This is part of the right-to-left scan of bayer-moore algorithm.. and it is essential for me to do it from reverse. Since my goal is to learn haskell, I am not using Data.ByteString. My function is as follows: matchReverse :: String -> String ->Int->(Bool,Int) matchReverse [] [] pos = (True,pos) matchReverse _ [] pos = (False,pos) matchReverse [] _ pos = (False,pos) matchReverse (x:xs) (y:ys) pos = let (matched,pos) = matchReverse xs ys (pos +1) in if matched then ((x==y),pos) else (False,pos) The behaviour I expected in four scenarios is as below: 1.matchReverse "kapilash" "kapilash" 0 --should return (True,0) 2.matchReverse "kapilash" "kapilast" 0 --should return (False,8) 3.matchReverse str1 str2 0 --should return (False,0) 4.matchReverse str1 str1 0 --should return (True,0) where str1 and str2 are defined as below: str1 = replicate 1000 'a' str2 = 'b':(replicate 999 'a') what confounds me is that it is able to identify the first element of the tuple in ALL the cases. Invoking fst on the each of the four calls instantly returns the expected value.(even for the cases 3 and 4 where, there are thousand elements) But it seems to go into an infinite loop while calculating the 'snd' of the tuple. Even for strings containing just one element each. can someone throw some light on this please? Why does it go into an infinite loop? Many thanks Kapilash -- I drink I am thunk.

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Haskell Weekly News: Issue 68 - January 05, 2008
by Don Stewart 06 Jan '08

06 Jan '08

--------------------------------------------------------------------------- Haskell Weekly News Issue 68 - January 05, 2008 --------------------------------------------------------------------------- Welcome to issue 68 of HWN, a newsletter covering developments in the [1]Haskell community. This HWN features new releases of the GHC and nhc98 Haskell compilers, a pre-release of darcs 2.0, several new user groups formed, and of course, more than 100 updated and new libraries 1. http://haskell.org/ Announcements GHC 6.8.2. The GHC Team [2]announced the release of GHC 6.8.2, featuring optimisation improvements, improvements to ghci and fixes to standalone deriving. 2. http://www.haskell.org/ghc/download_ghc_682.html nhc98 1.2 released. Malcolm Wallace [3]announced the release of nhc98 1.2. 1.20 is a refreshed release with many of the current core library packages included, and a variety of small bugfixes since the last release. It successfully compiles and runs more programs from the nobench suite than jhc, hbc, Hugs, or yhc. It generates an interpreted bytecode that, on the whole runs faster than that generated by Hugs or yhc, and in many cases is also faster than ghci. Although nhc98 is written in Haskell, you don't need an existing Haskell compiler on your platform to build nhc98 - a C compiler will do. Hence, it is portable to almost any unix-like machine with a 32-bit compatibility mode. Many useful build tools come included: hmake (the inspiration for ghc --make), hi (interactive read-eval-print, like Hugs or ghci), cpphs (Haskell-aware replacement for cpp) and hsc2hs (preprocessor for FFI code) 3. http://article.gmane.org/gmane.comp.lang.haskell.general/15770 darcs 2.0.0pre2. David Roundy [4]announced the availability of the second prerelease of [5]darcs two, darcs 2.0.0pre2. This release fixes several severe performance bugs that were present in the first prerelease. These issues were identified and fixed thanks to the helpful testing of Simon Marlow and Peter Rockai. We also added support for compilation under ghc 6.4, so even more users should be able to test this release. 4. http://article.gmane.org/gmane.comp.lang.haskell.cafe/33483 5. http://darcs.net/ The Monad.Reader Issue 9: SoC special. Wouter Swierstra [6]announced a new issue of The Monad.Reader, a 'Summer of Code Special' - it consists of three articles from student participants of Google's Summer of Code, describing the projects they worked on. 6. http://article.gmane.org/gmane.comp.lang.haskell.cafe/31848 What's happening with Haskell? The 13th HCAR. Andres Loeh [7]announced the 13th edition of the Haskell Communities and Activities Report 7. http://www.haskell.org/communities/ Teach yourself gtk2hs in 21 hours. Hans van Thiel [8]announced a Gtk2Hs basics tutorial, based on the Tony Gale and Ian Main GTK+2.0 tutorial, is now available for review and comment. 8. http://article.gmane.org/gmane.comp.lang.haskell.cafe/32671 Minimalistic Haskell blog framework. Paul Brown [9]announced a lightweight, experimental blog publishing application, [10]perpubplat 9. http://article.gmane.org/gmane.comp.lang.haskell.cafe/34503 10. http://datapr0n.com/repos/perpubplat atom. Tom Hawkins [11]announced the release of atom 2007.12; atom is a domain-specific language embedded in Haskell for describing real-time control applications 11. http://www.haskell.org/pipermail/haskell-cafe/2007-December/035742.html Hackage New and updated libraries in [12]the Hackage library database. 12. http://hackage.haskell.org/ * bytestring 0.9.0.4. Uploaded by DonaldStewart. [13]bytestring: Fast, packed, strict and lazy byte arrays with a list interface. * uuagc 0.9.5. Uploaded by ArieMiddelkoop. [14]uuagc: Attribute Grammar System of Universiteit Utrecht. * uulib 0.9.5. Uploaded by ArieMiddelkoop. [15]uulib: Haskell Utrecht Tools Library. * llvm 0.0.2. Uploaded by BryanOSullivan. [16]llvm: Bindings to the LLVM compiler toolkit. * HDBC-sqlite3 1.1.3.1. Uploaded by JohnGoerzen. [17]HDBC-sqlite3: Sqlite v3 driver for HDBC. * HDBC-odbc 1.1.3.1. Uploaded by JohnGoerzen. [18]HDBC-odbc: ODBC driver for HDBC. * dimensional 0.7.2. Uploaded by BjornBuckwalter. [19]dimensional: Statically checked physical dimensions.. * uulib 0.9.5. Uploaded by ArieMiddelkoop. [20]uulib: Haskell Utrecht Tools Library. * hsc3 0.1. Uploaded by RohanDrape. [21]hsc3: Haskell SuperCollider. * hosc 0.1. Uploaded by RohanDrape. [22]hosc: Haskell Open Sound Control. 13. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/bytestring-0.9.0… 14. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/uuagc-0.9.5 15. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/uulib-0.9.5 16. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/llvm-0.0.2 17. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/HDBC-sqlite3-1.1… 18. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/HDBC-odbc-1.1.3.1 19. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/dimensional-0.7.2 20. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/uulib-0.9.5 21. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hsc3-0.1 22. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hosc-0.1 * GLFW 0.2. Uploaded by PaulLiu. [23]GLFW: A binding for GLFW, An OpenGL Framework. * control-timeout 0.1. Uploaded by AdamLangley. [24]control-timeout: Timeout handling. * hiccup 0.35. Uploaded by KyleConsalus. [25]hiccup: Relatively efficient Tcl interpreter with support for basic operations. * phooey 2.0. Uploaded by ConalElliott. [26]phooey: Functional user interfaces. * reactive 0.0. Uploaded by ConalElliott. [27]reactive: Simple foundation for functional reactive programming. * phooey 1.4. Uploaded by ConalElliott. [28]phooey: Functional user interfaces. * hburg 1.1.1. Uploaded by IgorBohm. [29]hburg: Haskell Bottom Up Rewrite Generator. * hinotify 0.2. Uploaded by LennartKolmodin. [30]hinotify: Haskell binding to INotify. * cabal-rpm 0.3.3. Uploaded by BryanOSullivan. [31]cabal-rpm: RPM package builder for Haskell Cabal source packages.. * codec-libevent 0.1. Uploaded by AdamLangley. [32]codec-libevent: Cross-platform structure serialisation. 23. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/GLFW-0.2 24. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/control-timeout-… 25. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hiccup-0.35 26. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/phooey-2.0 27. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/reactive-0.0 28. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/phooey-1.4 29. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hburg-1.1.1 30. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hinotify-0.2 31. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/cabal-rpm-0.3.3 32. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/codec-libevent-0… * irc 0.4. Uploaded by TrevorElliott. [33]irc: A small library for parsing IRC messages.. * dlist 0.4. Uploaded by DonaldStewart. [34]dlist: Differences lists. * AutoForms 0.4.0. Uploaded by MadsLindstroem. [35]AutoForms: GUI library based upon generic programming (SYB3). * bktrees 0.2.1. Uploaded by JosefSvenningsson. [36]bktrees: A set data structure with approximate searching. * bktrees 0.2. Uploaded by JosefSvenningsson. [37]bktrees: A set data structure with approximate searching. * binary-strict 0.1. Uploaded by AdamLangley. [38]binary-strict: Binary deserialisation using strict ByteStrings. * haddock 0.9. Uploaded by SimonMarlow. [39]haddock: Haddock is a documentation-generation tool for Haskell libraries. * bytestring-mmap 0.2.0. Uploaded by DonaldStewart. [40]bytestring-mmap: mmap support for strict ByteStrings. * bytestring 0.9.0.3. Uploaded by DonaldStewart. [41]bytestring: Fast, packed, strict and lazy byte arrays with a list interface. * hiccup 0.3. Uploaded by KyleConsalus. [42]hiccup: Added by KyleConsalus, Wed Dec 19 17:00:42 PST 2007.. 33. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/irc-0.4 34. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/dlist-0.4 35. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/AutoForms-0.4.0 36. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/bktrees-0.2.1 37. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/bktrees-0.2 38. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/binary-strict-0.1 39. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/haddock-0.9 40. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/bytestring-mmap-… 41. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/bytestring-0.9.0… 42. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hiccup-0.3 * cedict 0.1.1. Uploaded by JasonDusek. [43]cedict: Convenient Chinese character lookup.. * TypeCompose 0.3. Uploaded by ConalElliott. [44]TypeCompose: Type composition classes & instances. * bytestring-mmap 0.1.2. Uploaded by DonaldStewart. [45]bytestring-mmap: mmap support for strict ByteStrings. * bytestring 0.9.0.2. Uploaded by DonaldStewart. [46]bytestring: Fast, packed, strict and lazy byte arrays with a list interface. * bytestring-mmap 0.1.1. Uploaded by DonaldStewart. [47]bytestring-mmap: mmap support for strict ByteStrings. * mkcabal 0.3. Uploaded by DonaldStewart. [48]mkcabal: Generate cabal files for a Haskell project. * terminfo 0.1. Uploaded by Judah Jacobson. [49]terminfo: Haskell bindings to the terminfo library.. * Cabal 1.2.3.0. Uploaded by Duncan Coutts. [50]Cabal: A framework for packaging Haskell software. * hxt 7.4. Uploaded by UweSchmidt. [51]hxt: A collection of tools for processing XML with Haskell.. * X11 1.4.1. Uploaded by Spencer Janssen. [52]X11: A binding to the X11 graphics library. 43. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/cedict-0.1.1 44. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/TypeCompose-0.3 45. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/bytestring-mmap-… 46. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/bytestring-0.9.0… 47. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/bytestring-mmap-… 48. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/mkcabal-0.3 49. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/terminfo-0.1 50. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/Cabal-1.2.3.0 51. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hxt-7.4 52. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/X11-1.4.1 * dataenc 0.10.1. Uploaded by Magnus Therning. [53]dataenc: Data encoding library currently providing Uuencode, Base64, Base64Url, Base32, Base32Hex, and Base16.. * bytestringreadp 0.1. Uploaded by Gracjan Polak. [54]bytestringreadp: A ReadP style parser library for ByteString. * encoding 0.3. Uploaded by HenningGuenther. [55]encoding: A library for various character encodings. * hslua 0.2. Uploaded by Gracjan Polak. [56]hslua: A Lua language interpreter embedding in Haskell. * xmonad-contrib 0.5. Uploaded by Spencer Janssen. [57]xmonad-contrib: Third party extensions for xmonad. * xmonad 0.5. Uploaded by SpencerJanssen. [58]xmonad: A tiling window manager. * pandoc 0.45. Uploaded by John MacFarlane. [59]pandoc: Conversion between markup formats. * markov-chain 0.0.1. Uploaded by Henning Thielemann. [60]markov-chain: Markov Chains for generating random sequences with a user definable behaviour.. * parsedate 3000.0.0. Uploaded by Bjorn Bringert. [61]parsedate: Data and time parsing for CalendarTime. * hackage2hwn 0.1. Uploaded by Don Stewart. [62]hackage2hwn: Convert hackage = Hackage RSS feeds to Haskell Weekly News format. 53. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/dataenc-0.10.1 54. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/bytestringreadp-… 55. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/encoding-0.3 56. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hslua-0.2 57. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/xmonad-contrib-0… 58. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/xmonad-0.5 59. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/pandoc-0.45 60. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/markov-chain-0.0… 61. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/parsedate-3000.0… 62. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hackage2hwn-0.1 * hask-home 2007.12.6. Uploaded by BjornBringert. [63]hask-home: Generate homepages for cabal packages. * hmarkup 3000.0.1. Uploaded by BjornBringert. [64]hmarkup: Simple wikitext-like markup format implementation.. * hspread 0.2. Uploaded by AndreaVezzosi. [65]hspread: A client library for the spread toolkit. * pcap 0.4.2. Uploaded by BryanOSullivan. [66]pcap: A system-independent interface for user-level packet capture. * hogg 0.3.0. Uploaded by ConradParker. [67]hogg: Library and tools to manipulate the Ogg container format. * Finance-Quote-Yahoo 0.4.1. Uploaded by BradClawsie. [68]Finance-Quote-Yahoo: Obtain quote data from finance.yahoo.com. * Monadius 0.9.20071204. Uploaded by GwernBranwen. [69]Monadius: 2-D arcade scroller. * Shu-thing 1.0.20071203. Uploaded by GwernBranwen. [70]Shu-thing: A vector shooter game. * hmatrix 0.1.1.0. Uploaded by AlbertoRuiz. [71]hmatrix: Linear algebra and numerical computations. * HTTP 3001.0.3. Uploaded by BjornBringert. [72]HTTP: Added by BjornBringert, Fri Nov 30 14:50:55 PST 2007.. 63. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hask-home-2007.1… 64. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hmarkup-3000.0.1 65. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hspread-0.2 66. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/pcap-0.4.2 67. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hogg-0.3.0 68. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/Finance-Quote-Ya… 69. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/Monadius-0.9.200… 70. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/Shu-thing-1.0.20… 71. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hmatrix-0.1.1.0 72. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/HTTP-3001.0.3 * rss 3000.0.1. Uploaded by BjornBringert. [73]rss: A library for generating RSS 2.0 feeds.. * haxr 3000.0.1. Uploaded by BjornBringert. [74]haxr: XML-RPC client and server library.. * fitsio 0.1. Uploaded by EricSessoms. [75]fitsio: A library for reading and writing data files in the FITS data format.. * YamlReference 0.6. Uploaded by Oren Ben Kiki. [76]YamlReference, YAML reference implementation * LambdaShell 0.9.1. Uploaded by Robert Dockins. [77]LambdaShell, simple shell for evaluating lambda expressions * Shellac 0.9.1. Uploaded by Robert Dockins. [78]Shellac, a framework for creating shell envinronments * EdisonCore 1.2.1.1. Uploaded by Robert Dockins. [79]EdisonCore, a library of efficent, purely-functional data structures (Core Implementations) * hmatrix 0.1.0.0. Uploaded by Alberto Ruiz. [80]hmatrix, linear algebra and numerical computations * strict-concurrency 0.1. Uploaded by Don Stewart. [81]strict-concurrency, strict concurrency abstractions * X11 1.4.0. Uploaded by Don Stewart. [82]X11, binding to the X11 graphics library 73. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/rss-3000.0.1 74. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/haxr-3000.0.1 75. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/fitsio-0.1 76. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/YamlReference-0.6 77. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/LambdaShell-0.9.1 78. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/Shellac-0.9.1 79. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/EdisonCore-1.2.1… 80. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hmatrix-0.1.0.0 81. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/strict-concurren… 82. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/X11-1.4.0 * safecopy 0.3. Uploaded by David Himmelstrup. [83]safecopy, binary serialization with version control * HaXml 1.13.3. Uploaded by Malcolm Wallace. [84]HaXml, utilities for manipulating XML documents * c2hs 0.15.1. Uploaded by Duncan Coutts. [85]c2hs, C->Haskell Interface Generator * calc 0.1. Uploaded by Austin Seipp. [86]calc, small compiler for arithmetic expressions. * miniplex 0.2.1. Uploaded by Lukas Mai. [87]miniplex, simple 1-to-N interprocess communication * sat 1.1.1. Uploaded by Andrii Zvorygin. [88]sat, CNF SATisfier * dimensional 0.7.1. Uploaded by Bjorn Buckwalter. [89]dimensional, statically checked physical dimensions * hxt 7.4. Uploaded by Uwe Schmidt. [90]hxt, collection of tools for processing XML with Haskell. * dlist 0.3.2. Uploaded by Don Stewart. [91]dlist, difference lists. A list type supporting fast append. * mkcabal 0.2. Uploaded by Don Stewart. [92]mkcabal, generate cabal files for a Haskell project 83. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/safecopy-0.3 84. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/HaXml-1.13.3 85. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/c2hs-0.15.1 86. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/calc-0.1 87. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/miniplex-0.2.1 88. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/sat-1.1.1 89. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/dimensional-0.7.1 90. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hxt-7.4 91. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/dlist-0.3.2 92. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/mkcabal-0.2 * Chart 0.5. Uploaded by Tim Docker. [93]Chart, a library for generating 2D Charts and Plots * MaybeT 0.1.1. Uploaded by Don Stewart. [94]MaybeT, MaybeT monad transformer * regex-pcre 0.93. Uploaded by Chris Kuklewicz. [95]regex-pcre, replaces Text.Regex * fixpoint 0.1. Uploaded by Roman Leshchinskiy. [96]fixpoint, data types as fixpoints * ChasingBottoms 1.2.2. Uploaded by Nils Anders Danielsson. [97]ChasingBottoms, support for testing partial and infinite values * GrowlNotify 0.3. Uploaded by Nicholas Burlett. [98]GrowlNotify, notification utility for Growl * pcap 0.4.1. Uploaded by Bryan OSullivan. [99]pcap, a system-independent interface for user-level packet capture * bencode 0.3. Uploaded by David Himmelstrup. [100]bencode, parser and printer for bencoded data. * stream-fusion 0.1.1. Uploaded by Don Stewart. [101]stream-fusion, provides the standard Haskell list library reimplemented to allow stream fusion. This should in general provide faster list operations, and faster code for list-heavy programs. * HTTP 3001.0.2. Uploaded by Bjorn Bringert. [102]HTTP, library for client-side HTTP 93. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/Chart-0.5 94. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/MaybeT-0.1.1 95. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/regex-pcre-0.93 96. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/fixpoint-0.1 97. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/ChasingBottoms-1… 98. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/GrowlNotify-0.3 99. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/pcap-0.4.1 100. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/bencode-0.3 101. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/stream-fusion-0.… 102. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/HTTP-3001.0.2 * X11-xft 0.2. Uploaded by Clemens Fruhwirth. [103]X11-xft, bindings to the Xft, X Free Type interface library, and some Xrender parts * GrowlNotify 0.1. Uploaded by Nicholas Burlett. [104]GrowlNotify, notification utility for Growl. * HsHaruPDF 0.0.0. Uploaded by Audrey Tang. [105]HsHaruPDF, Haskell binding to libharu * unicode-normalization 0.1. Uploaded by Reinier Lamers. [106]unicode-normalization, Unicode normalization using the ICU library * uniplate 1.0.1. Uploaded by Neil Mitchell. [107]uniplate, uniform type generic traversals * lax-0.0.0. Uploaded by Wolfgang Jeltsch. [108]lax, Lax arrows are variants of other arrows which are ?less strict? than the original arrows. They can be used, for example, to produce I/O fixpoints in situations where fixIO would fail. * fastcgi 3001.0.1. Uploaded by Bjorn Bringert. [109]fastcgi, a Haskell library for writing FastCGI programs 103. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/X11-xft-0.2 104. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/GrowlNotify-0.1 105. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/HsHaruPDF-0.0.0 106. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/unicode-normaliz… 107. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/uniplate-1.0.1 108. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/lax-0.0.0 109. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/fastcgi-3001.0.1 Conference roundup New user groups * [110]Portland Functional Programmers Group * [111]FPSIG @ Southampton * [112]SingHaskell 110. http://groups.google.com/group/pdxfunc 111. http://article.gmane.org/gmane.comp.lang.haskell.cafe/32753 112. http://article.gmane.org/gmane.comp.lang.haskell.cafe/32268 Jobs Prototyping. Peter Verswyvelen [113]announced a job using Haskell for prototyping computer animation and games 113. http://article.gmane.org/gmane.comp.lang.haskell.cafe/33377 Blog noise [114]Haskell news from the [115]blogosphere. 114. http://planet.haskell.org/ 115. http://haskell.org/haskellwiki/Blog_articles * [116]Small shots of lambda calculus * [117]Pattern Matching in Ruby * [118]Haskell 'words' and Perl 'split' * [119]Word numbers, Part 4: Sort the words, sum the numbers * [120]Improve Your C#! Borrow from F#... * [121]Sun battling Microsoft (over F#?) * [122]zip in F# and Haskell * [123]Random numbers in Haskell * [124]A survey of Haskell unicode support * [125]Using Haskell for scripting tasks 116. http://fmota.tk/2007/11/small-shots-of-lambda-calculus-part-iii.html 117. http://blog.pretheory.com/arch/2007/11/pattern_matching_in_ruby_1.php 118. http://osfameron.vox.com/library/post/haskell-words-and-perl-split.html 119. http://conway.rutgers.edu/~ccshan/wiki/blog/posts/WordNumbers4/ 120. http://diditwith.net/2007/11/14/ImproveYourCBorrowFromF.aspx 121. http://vanirsystems.com/danielsblog/?p=227 122. http://jyliao.blogspot.com/2007/11/learning-wpf-with-f-dock-and-grid.html 123. http://monadicheadaches.blogspot.com/2007/11/random-numbers-where-it-all-st… 124. http://blog.kfish.org/2007/10/survey-haskell-unicode-support.html 125. http://pinderkent.blogsavy.com/archives/142 * [126]Princeton lost the DARPA Grand Challenge because of a C# memory leak * [127]Laziness in C#/LINQ * [128]Getting functional programming: currying * [129]The magic foldr * [130]Nested Parallel List Comprehensions * [131]FFI in Haskell * [132]Broadening ones horizons * [133]Monad Wars - 1: the Prompt * [134]Monad Wars - 2: the command line * [135]Holy Shmoly, GHC Haskell 6.8 smokes Python and Ruby away! 126. http://www.codeproject.com/showcase/IfOnlyWedUsedANTSProfiler.asp 127. http://gavinbierman.blogspot.com/2007/11/laziness-in-clinq.html 128. http://overwatering.blogspot.com/2007/11/currying.html 129. http://caos.di.uminho.pt/~ulisses/blog/2007/11/20/foldr-the-magic-function/ 130. http://tomschrijvers.blogspot.com/2007/11/nested-parallel-list-comprehensio… 131. http://notes-on-haskell.blogspot.com/2007/02/ffi-in-haskell.html 132. http://ms-os.com/showthread.php?t=116050 133. http://osfameron.vox.com/library/post/monad-wars---1-the-prompt.html 134. http://osfameron.vox.com/library/post/monad-wars---2-the-command-line.html 135. http://www.cse.unsw.edu.au/~dons/blog/2007/11/29#smoking * [136]Use those extra cores and beat C today! (Parallel Haskell redux) * [137]Parallelizing Haskell * [138]Python, Haskell, Ruby Smackdown * [139]Legitimate uses of micro-benchmarks: parameter passing and function call costs * [140]Holy Shmoly, GHC does some magic all by itself! * [141]PARE - PARallel Execution in Erlang - a response to Haskell * [142]Haskell design patterns are (probably) needed * [143]Deriving a Virtual Machine * [144]Games, cores, and functional languages * [145]Structure of a functional Java, er, method 136. http://www.cse.unsw.edu.au/~dons/blog/2007/11/29#smoking-4core 137. http://cmssphere.blogspot.com/2007/11/parallelizing-haskell.html 138. http://feedingthesnake.wordpress.com/2007/11/30/python-haskell-ruby-smackdo… 139. http://eigenclass.org/hiki/legitimate-microbenchmarks 140. http://geekrant.wordpress.com/2007/11/29/holy-shmoly-ghc-does-some-magic-al… 141. http://chlorophil.blogspot.com/2007/11/pare-parallel-execution-in-erlang.ht… 142. http://jpmoresmau.blogspot.com/2007/11/haskell-design-patterns-are-probably… 143. http://www.iis.sinica.edu.tw/~scm/?p=42 144. http://www.antipode.ca/2007/games-cores-and-functional-languages/ 145. http://jpmoresmau.blogspot.com/2007/11/structure-of-functional-java-er-meth… * [146]Current Fixation: Haskell * [147]Multicores, F# and SPJ: leading people to Haskell * [148]The IO Monad for People who Simply Don't Care * [149]Why I chose to learn Haskell * [150]Some Playing with Derivatives * [151]Solve Ball Clock Puzzle in Python and Haskell * [152]Back to functional languages... at least for a while? * [153]Overloading Semicolon, or, monads from 10,000 Feet * [154]Getting started with Haskell * [155]Arrows first encounter 146. http://onerousmachinations.blogspot.com/2007/11/current-fixation-haskell.ht… 147. http://nxtgenug.spaces.live.com/Blog/cns!59F714755D6E2A69!221.entry 148. http://sigfpe.blogspot.com/2007/11/io-monad-for-people-who-simply-dont.html 149. http://offthelip.org/?p=91 150. http://cdsmith.wordpress.com/2007/11/29/some-playing-with-derivatives/ 151. http://the-little-haskeller.blogspot.com/2007/11/solve-ball-clock-puzzle-in… 152. http://afurtado1980.spaces.live.com/Blog/cns!63514833CE40C143!518.entry 153. http://osteele.com/archives/2007/12/overloading-semicolon 154. http://talkingcode.co.uk/2007/12/03/getting-started-with-haskell/ 155. http://monadicheadaches.blogspot.com/2007/12/arrows-first-encounter.html * [156]Arithmetic for lists * [157]Functional Programming on .NET - Part 1 * [158]N-Queens in Haskell * [159]N-Queens in the writer monad * [160]Unit testing in Haskell * [161]Calculating the reflect-rotate-translate normal form for an isometry of the plane in Haskell, and verifying it with QuickCheck * [162]Visualizing 2D convex hull using Gtk and OpenGL in Haskell * [163]Hugs for the Nintendo DS * [164]Comparative terseness of Perl and Haskell * [165]Note on point-free programming style 156. http://wadler.blogspot.com/2007/12/arithmetic-for-lists.html 157. http://zerogradient.wordpress.com/2007/12/05/functional-programming-on-net-… 158. http://therning.org/magnus/archives/330 159. http://cdsmith.wordpress.com/2007/12/09/some-basic-stuff-the-writer-monad/ 160. http://hitesh-jasani.blogspot.com/2007/12/unit-testing-with-hunit-in-haskel… 161. http://www.kennknowles.com/blog/2007/12/03/calculating-the-reflect-rotate-t… 162. http://www.kennknowles.com/blog/2007/11/20/visualizing-2d-convex-hull-using… 163. http://closuretohome.blogspot.com/2007/12/hugs-for-nintendo-ds.html 164. http://blog.plover.com/2007/11/30/#pow-sqrt 165. http://blog.plover.com/prog/haskell/pointfree.html * [166]Haskell Fibonacci Revisited * [167]PXSL Tools 1.0: Your ticket out of XML Hell * [168]Haskell is kind of cool * [169]Learning Haskell with ProjectEuler * [170]Infinite lazy Knuth-Bendix completion for monoids in Haskell * [171]Hugs for the Nintendo DS * [172]My Type of Language... * [173]Catching pods with hpodder * [174]Hamming's problem * [175]Sharper function operators 166. http://chasethedevil.blogspot.com/2007/12/haskell-fibonacci-revisited.html 167. http://blog.moertel.com/articles/2007/12/17/pxsl-tools-1-0-your-ticket-out-… 168. http://www.goesping.org/archives/2007/12/18/haskell-is-kind-of-cool/ 169. http://www.robdickerson.net/?p=12 170. http://www.kennknowles.com/blog/2007/12/20/infinite-lazy-knuth-bendix-compl… 171. http://blog.closuretohome.com/2007/12/hugs-for-nintendo-ds.html 172. http://lambdalounge.blogspot.com/2007/12/my-type-of-language.html 173. http://lorenzod8n.wordpress.com/2007/12/22/catching-pods-with-hpodder/ 174. http://conway.rutgers.edu/~ccshan/wiki/blog/posts/Hamming/ 175. http://blog.closuretohome.com/2008/01/sharper-function-operators.html * [176]Xiangqiboard: play Xiangqi against a computer opponent * [177]Haskell is kind of cool * [178]FParsec - A Parser Combinator Library for F# * [179]RSA-Haskell * [180]LLVM bindings for Haskell * [181]perpubplat 0.9 - You're Looking at It: blog framework for Haskell * [182]The point of pointfree * [183]qtHaskell * [184]Web Objects and the underappreciated recursive do * [185]Equality operators in PHP and Haskell 176. http://xiangqiboard.blogspot.com/2007/12/gnuxiangqi-angekndigt.html 177. http://www.goesping.org/archives/2007/12/18/haskell-is-kind-of-cool/ 178. http://www.quanttec.com/fparsec/ 179. http://netsuperbrain.com/rsa-haskell.html 180. http://www.serpentine.com/blog/2008/01/03/llvm-bindings-for-haskell/ 181. http://mult.ifario.us/p/perpubplat-0-9-you-re-looking-at-it 182. http://www.vex.net/~trebla/weblog/pointfree.html 183. http://qthaskell.sourceforge.net/ 184. http://www.alpheccar.org/en/posts/show/89 185. http://www.syntaxpolice.org/index.php/?q=node%2F419 * [186]Pushing Haskell's type system to the limits: A reflective JSON serializer * [187]A Wake Up Call for the Logic Programming Community * [188]Design your functions for partial application * [189]Taxicab Numbers * [190]Composing Contracts * [191]HTTP content-type comparison at the type level * [192]Haskell-Join-Rules * [193]Exploring JPEG * [194]What's interesting to me about SquirrelMail attack * [195]Haskell and F#: Language Design 186. http://lingnerd.blogspot.com/2007/12/pushing-haskells-type-system-to-limits… 187. http://www.cs.kuleuven.ac.be/~dtai/projects/ALP/newsletter/dec07/content/Ar… 188. http://www.serpentine.com/blog/2007/12/26/design-your-functions-for-partial… 189. http://notes-on-haskell.blogspot.com/2007/12/taxicab-numbers.html 190. http://contracts.scheming.org/ 191. http://www.alpheccar.org/en/posts/show/88 192. http://taichi.ddns.comp.nus.edu.sg/taichiwiki/HaskellJoinRules 193. http://www.imperialviolet.org/binary/jpeg/ 194. http://www.syntaxpolice.org/index.php/?q=node%2F418 195. http://corsis.blogspot.com/2008/01/haskell-and-f-language-design.html * [196]An example of Haskell's beauty * [197]My resolve to learn Haskell has become stronger after having watched 'A Taste of Haskell' * [198]Emacs love w/ Haskell * [199]Finding my way * [200]Why not Scala? * [201]A Different Kind of Obscurity * [202]Languages that save you some typing 196. http://blog.whoop.as/?p=1668 197. http://rmathew.blogspot.com/2008/01/taste-of-haskell.html 198. http://blog.whoop.as/?p=1665 199. http://nointernalmonologue.blogspot.com/2008/01/finding-my-way.html 200. http://unenterprise.blogspot.com/2008/01/why-not-scala.html 201. http://ddvlad.wordpress.com/2007/12/14/a-different-kind-of-obscurity/ 202. http://daltonic.blogspot.com/2008/01/language-that-saves-you-some-typing.ht… Quotes of the Week * Conal: For me, the heart of functional programming is exactly this separation between model and presentation. The former is naturally functional and compositional, while the latter is often imperative/sequential and not-so-compositional. IO belongs with the latter. * ddarius: has programmed too much in Haskell. He now produces code that -compiles- and works the first time * disspy: If all you know is C, everything begins to look like a segmentation fault. * markedtrees: (On the city of Haskell) Ah yes, Haskell. Where all the types are strong, all the men carry arrows, and all the children are above average. * ola-bini: Haskell's type system is really nice, for example, but OCaml's really feels like half of it exists just to cover up holes in the other half, I'm half way into Erlang, but for several reasons the language feels very primitive. * so1i.warazd: I'm more and more comfortable spending time with Haskell these days. Haskell may not be the next thing, but whatever the next big thing is, it's probably going to have Haskelly fingerprints all over it?.. * sylvan: think that the perceived difficulty in using purely functional programming is probably a bit exaggerated these days, as all it means is 'we're explicit about where side effects occur' * falvo: I really wish that someone would come up with a type-safe replacement for the likes of Python. Oh, wait, it's called Haskell! Unfortunately, I'm forbidden from using Haskell at work. Sigh * Tyler Spaulding: eventually even 'simple' programs will nned multiple threads. Does that mean developers will suddenly flock to Haskell? Again, no. Language designers are well aware of the situation. Sun and Microsoft are constantly working on improving the Java and .NET frameworks. And by the time the average programmer needs it, both will have plenty of support for easy threading * ricky clarkson: Haskell is full of Aha and Hah moments for me * five9a2: Concurrency aside, I find it common to write Haskell code that is as fast as C. It is true that for most things, the C can be tweaked to go a bit faster, but that tweaking needs to be done on a case-by-case basis. In Haskell, it is easier to compose optimized components. Better algorithms beat an optimized compiler any day and using the best algorithms everywhere in C code tends to be painful, error-prone, and usually disparaged as premature optimization. * Jeff Moser: It's been this fear of skills rot that has pushed me to look into Lisp, Haskell, F#, Erlang, and other languages to avoid The Blub Paradox. * NFJS 2008 predictions: If you've never programmed in Haskell, now's a good time to learn, because those concepts and syntax are fast making their way towards you... * The honey monster: With the advent of multi-core CPUs and the promise of many core processors in the near future it occurrs to me that my interest in functional programming languages could not of happened at a more opportune time. It is not that imperative programming languages are not as capable, merely that functional programming languages seem to be more natural fit About the Haskell Weekly News New editions are posted to [203]the Haskell mailing list as well as to [204]the Haskell Sequence and [205]Planet Haskell. [206]RSS is also available, and headlines appear on [207]haskell.org. Headlines are available as [208]PDF. To help create new editions of this newsletter, please see the [209]contributing information. Send stories to dons at galois.com. The darcs repository is available at darcs get [210]http://code.haskell.org/~dons/code/hwn/ 203. http://www.haskell.org/mailman/listinfo/haskell 205. http://planet.haskell.org/ 207. http://haskell.org/ 208. http://code.haskell.org/~dons/code/hwn/archives/20080105.pdf 209. http://haskell.org/haskellwiki/HWN 210. http://code.haskell.org/~dons/code/hwn/

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bytestring 0.9.0.4
by Don Stewart 05 Jan '08

05 Jan '08

2.5 years after the first release, bytestring 0.9.0.4 is now available on hackage, http://hackage.haskell.org/cgi-bin/hackage-scripts/package/bytestring-0.9.0… Changes since the 0.9 release include: * support for bytestring literals (use -XOverloadedStrings) * make Data.ByteString.Lazy.Char8.lines lazier * fixes Handle resource leak in getContents/readFile * faster isSpace operations * performance improvements The most notable change is the instance IsString for strict and lazy bytestrings, enabling bytestrings to be written as direct string literals, without needing 'pack'. That is, the following is valid: import Data.ByteString.Char8 main = print ("abcdef" :: ByteString) (and the compile will even turn the pack into a no-op at compile time). Or, using the (soon to be released pcre-light package), bytestring regex literals can be written as: compile "a(.*)b" where compile :: ByteString -> Either String Regex With -XOverloadedStrings, the 'pack'for the regex is inferred. -- Don & Duncan

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HsColour version confusion
by Adrian Hey 04 Jan '08

04 Jan '08

Hello, I'm confused about which HsColour version I should be using with Haddock/Cabal (on Windows). According to this page.. http://www.cs.york.ac.uk/fp/darcs/hscolour/ ..the latest version is 1.9. But the latest version in Hackage is 1.6, the latest version in the ftp downloads dir is 1.8, unless you want a pre-compiled windows version in which case you're stuck with 1.3 :-) Anyone know what's going on? Thanks -- Adrian Hey

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ANN / CFC: minimalistic haskell blogging web application (perpubplat)
by Paul Brown 04 Jan '08

04 Jan '08

All -- I've spent some time on cleaning up my hobby blog publishing software and setting up a darcs repository, so I'll throw it out there for criticism or suggestions: darcs get http://datapr0n.com/repos/perpubplat It's running my blog (http://mult.ifario.us) It's relatively lightweight in that it doesn't use a framework but still weighs in at <1500 LOC with comments, but it does rely on the (Thanks, Bjorn!) FastCGI and XHTML combinator libraries. I have some plans for handling comments and the like, but things I'd like to figure out: - Turn the blog data model into a monad. - An idiomatic approach to handling conditional GET and E-Tag, i.e., send a 304 response if things aren't modified. Thanks in advance. -- paulrbrown(a)gmail.com http://mult.ifario.us/

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ANN / CFP - LLVM bindings for Haskell
by Bryan O'Sullivan 04 Jan '08

04 Jan '08

This is an early release of Haskell bindings for the popular LLVM compiler infrastructure project. If you don't know what LLVM is, it's a wonderful toybox of compiler components, from a complete toolchain supporting multiple architectures through a set of well-defined APIs and IR formats that are designed for building interesting software with. The official LLVM home page is here: http://llvm.org/ The Haskell bindings are based on Gordon Henriksen's C bindings. The C bindings are almost untyped, but the Haskell bindings re-add type safety to prevent runtime crashes and general badness. Currently, the entire code generation system is implemented, with most LLVM data types supported (notably absent are structs). Also plugged in is JIT support, so you can generate code at runtime from Haskell and run it immediately. I've attached an example. Please join in the hacking fun! darcs get http://darcs.serpentine.com/llvm If you want a source tarball, fetch it from here: http://darcs.serpentine.com/llvm/llvm-0.0.2.tar.gz (Hackage can't host code that uses GHC 6.8.2's language extension names yet.) There's very light documentation at present, but it ought to be enough to get you going. <b

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