- Haskell-Cafe - Haskell.org

CURL and threads
by Eugene Dzhurinsky 18 Feb '10

18 Feb '10

Hello, all! Can somebody please explain, what is the best way of using CURL with several threads? I wrote simple client, which tries to authenticate against HTTP server. With running this client, it starts to eat memory insanely (and I know this code is far, far away of even being close to be called good one ) ========================================================================================= module NTLMTest where import System.IO import Network.Curl import Control.Concurrent import Control.Concurrent.Chan type ResponseState = Either Bool String type RespChannel = Chan ResponseState delay = 500 * 1000 isResponseOk :: String -> CurlResponse -> ResponseState isResponseOk username response = case respCurlCode response of CurlOK -> Left True _ -> Right $ username ++ " => " ++ respStatusLine response ++ " :: " ++ (show . respStatus $ response) checkAuthResponse :: RespChannel -> String -> String -> String -> IO () checkAuthResponse state user passwd url = do response <- curlGetResponse_ url [CurlHttpAuth [HttpAuthAny], CurlUserPwd $ user ++ ":" ++ passwd] writeChan state $ isResponseOk user response threadDelay $ delay runHTTPThread :: RespChannel -> (String,String) -> IO () runHTTPThread state (user,passwd) = checkAuthResponse state user passwd url url = "http://localhost:8082/" credentials = map (\i -> ("user" ++ show i,"123456")) [1..21] main = withCurlDo $ do chan <- newChan :: IO (RespChannel) mapM_ ( \cred -> forkIO $ runHTTPThread chan cred ) credentials dumpChannel chan $ length credentials main where dumpChannel :: RespChannel -> Int -> IO () dumpChannel _chan n | n == 0 = return () | otherwise = do state <- readChan _chan case state of (Left _) -> return () --putStrLn "OK" (Right err) -> putStrLn err dumpChannel _chan $ n-1 ========================================================================================= If I get rid of forkIO - it stops at 40-50 megabytes and don't raise memory usage anymore. Also, I noticed that (either because of buffering, or may be something else) results are appearing on console much slower than if I simply use "wget" with looping in shell script. JMeter also reports awesome speed, so server can authenticate tens of concurrent users per second (thus it's not server or connection bandwidth issue). Hopefully, someone could help me in overcoming my ignorance :) -- Eugene N Dzhurinsky

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ANN: iteratee-parsec 0.0.1
by Maciej Piechotka 18 Feb '10

18 Feb '10

Iteratee-parsec is a library which allows to have a parsec (3) parser in IterateeG monad. It contains 2 implementations: - John Lato's on public domain. It is based on monoid and design with short parsers in mind. - Mine on MIT. It is based on single-linked mutable list. It seems to be significantly faster for larger parsers - at least in some cases - but it requires a monad with references (such as for example IO or ST). Regards

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Re : Friedberg numberings
by Pierre-Etienne Meunier 18 Feb '10

18 Feb '10

Hi, In fact it is not quite hard to see that such a numbering exists : just take any numbering of all Turing machines, say {\phi_i}, then remove all indices i such that there is j<i such that \phi_j = \phi_i (equality is mathematically correctly defined between functions from N to N). Ah, and also, notice that what you call a "programming language" is nothing else than an enumeration of all Turing machines. However, if by "construction" you meant "recursive construction", i.e. for another enumeration (\psi_i), find a Turing machine computing for any i, the index j such that \phi_j=\psi_i, then it is clear that it is not possible : it would allow to decide the equality problem for Turing machines. Hope this helps...

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Friedberg numberings.
by Grigory Sarnitskiy 18 Feb '10

18 Feb '10

Hello! The question is not about Haskell, but I don't know where else to ask. In the book "Computable functions" by Vereshchagin and Shen it is said that "it is possible to invent a programming language such that each programming problem has a unique solution in it". The author claims that this statement is a rewording of the theorem, that there is a universal computable function, such that any computable function has exactly one number. I wonder has such language been actually constructed? the book itself (look at the bottom of p 30 for the statement): http://books.google.ru/books?id=A6uvsks0abgC&pg=PA30#v=onepage&q=&f=false

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[Fwd: Re: [Haskell-cafe] Category Theory woes]
by Mike Pentney 18 Feb '10

18 Feb '10

As well as books and reading material online, nowadays you can also find video lectures...for example, the following was at the top of Googling "category theory video": http://golem.ph.utexas.edu/category/2007/09/the_catsters_on_youtube.html Cheers, Mike. Nick Rudnick wrote: > I haven't seen anybody mentioning «Joy of Cats» by Adámek, Herrlich & > Strecker: > > It is available online, and is very well-equipped with thorough > explanations, examples, exercises & funny illustrations, I would say > best of university lecture style: > http://katmat.math.uni-bremen.de/acc/. (Actually, the name of the book > is a joke on the set theorists' book «Joy of Set», which again is a > joke on «Joy of Sex», which I once found in my parents' bookshelf... ;-)) > > Another alternative: Personally, I had difficulties with the somewhat > arbitrary terminology, at times a hindrance to intuitive understanding > - and found intuitive access by programming examples, and the book was > «Computational Category Theory» by Rydeheart & Burstall, also now > available online at http://www.cs.man.ac.uk/~david/categories/book/, > done with the functional language ML. Later I translated parts of it > to Haskell which was great fun, and the books content is more beginner > level than any other book I've seen yet. > > The is also a programming language project dedicated to category > theory, «Charity», at the university of Calgary: > http://pll.cpsc.ucalgary.ca/charity1/www/home.html. > > Any volunteers in doing a RENAME REFACTORING of category theory > together with me?? ;-)) > > Cheers, > > Nick >

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Re: Pointfree composition for higher arity
by oleg＠okmij.org 18 Feb '10

18 Feb '10

Sean Leather wrote: > (...) :: (c -> d) -> (a -> b -> c) -> a -> b -> d > (...) f g x y = f (g x y) > Does anybody else care about this? What are some alternative > solutions? Here is a different solution: http://okmij.org/ftp/Haskell/polyvariadic.html#polyvar-comp f:: a1->a2-> .... ->cp (where cp is not a function type) g:: cp->d f `mcomp` g:: a1->a2-> .... ->d Now that we know how to generically decide if a type is not a functional type, mcomp can be defined fully generically, for any type cp that is not a function. If there is interest, I can write that code. One particular application of the mcomp combinator is the prod combinator: Given two functions, f:: a1->a2->...->an->c |c,d non-exponential types g:: b1->b2->...->bn->d their product f `prod` g:: a1->a2->...->an->b1->b2->...->bn->(c,d) The number of as and bs is arbitrary. The definition of prod is very simple: > prod = (. ((. (,)) . mcomp)) . mcomp The web page http://okmij.org/ftp/Haskell/polyvariadic.html#categorical-max3 gives a few explanations and further examples.

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What is the meaning of tilde ("~") symbol
by kg 17 Feb '10

17 Feb '10

Hi, I'm reading the following subject : http://www.haskell.org/pipermail/haskell-cafe/2007-July/028227.html In the sample code, we can see : instance ReadAsAnyOf () ex where readAsAnyOf ~() = mzero And, I've search the meaning of the symbol "~", but I've found nothing about this (note that's not easy to search "~" on google ...) Could you give me a link about this, or explain me it ? Thx in advance.

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ANN: concurrent-extra-0.1
by Roel van Dijk 17 Feb '10

17 Feb '10

Hello, We would like to announce the release of concurrent-extra [1]. A library which offers a few extra synchronization primitives. These primitives are found in the standard libraries of languages like Java and Python, but not in Haskell. Quick overview: * Lock: Enforce exclusive access to a resource. Also known as a mutex or a binary semaphore. * RLock: A lock which can be acquired multiple times by the same thread. Also known as a reentrant mutex. * Event: Wake multiple threads by signaling an event. Includes both pessimistic and optimistic versions. * ReadWriteLock: Multiple-reader, single-writer locks. Used to protect shared resources which may be concurrently read, but only sequentially written. * ReadWriteVar: Concurrent read, sequential write variables. Plug & Play: cabal install concurrent-extra Darcs: darcs get http://code.haskell.org/~roelvandijk/code/concurrent-extra/ Thanks to Neil Brown and Simon Marlow for an initial review. Comments are still more than welcome! Regards, Roel & Bas van Dijk [1] http://hackage.haskell.org/package/concurrent-extra

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Lambda's
by Henk-Jan van Tuyl 17 Feb '10

17 Feb '10

I love lambda's: http://hawtness.com/2009/12/30/wtf-girl-photo-more-reasons-why-half-life-is… -- Regards, Henk-Jan van Tuyl -- http://Van.Tuyl.eu/ http://members.chello.nl/hjgtuyl/tourdemonad.html --

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RFC: concurrent-extra
by Roel van Dijk 17 Feb '10

17 Feb '10

Hello, We wrote a small library (1) which offers a few extra synchronization primitives. These primitives are found in the standard libraries of languages like Java and Python, but not in Haskell. Before releasing concurrent-extra on hackage, we would like some comments on its name, design, implementation, documentation (2) and general usefulness. All primitives are implemented with MVars and IORefs, except for Control.Concurrent.STM.Event. There is a small test suite which tests some properties: cabal configure -ftest cabal build cabal test The test suite still needs to be expanded a great deal. We found that testing concurrent algorithms is really hard. Now we test things like "this shouldn't deadlock" by checking if it doesn't take too long. But that doesn't feel very formal. Is there a more principled approach to testing concurrent algorithms in Haskell? After writing our version of a read-write lock we noticed the package rwlock (3) on hackage. But there is a difference: rwlock is implemented with STM while our version is implemented entirely with MVars. Regards, Roel & Bas van Dijk 1 - http://code.haskell.org/~roelvandijk/code/concurrent-extra/ 2 - http://code.haskell.org/~roelvandijk/code/concurrent-extra/doc/html/concurr… 3 - http://hackage.haskell.org/package/rwlock

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Example for RVarT?
by Kemps-Benedix, Torsten 17 Feb '10

17 Feb '10

Hello folks, is there an example (simpe or not) for the use of Data.Random.RVarT with an underlying monad other than Identity, e.g. StateT, ReaderT etc.? Thx Torsten

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Notes on migrating from uvector to vector
by Don Stewart 17 Feb '10

17 Feb '10

I've summarised my notes on how to migrate array code from the uvector package to Roman's vector package: http://donsbot.wordpress.com/2010/02/15/migrating-from-uvector-to-vector/ And I'll take this opportunity to declare that uvector is now in official maintainance-only mode. Enjoy the new decade of flexible, fusible, fast arrays for Haskell! -- Don

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Efficient M to N conversion on fusion?
by iquiw 17 Feb '10

17 Feb '10

Hi, Is there any efficient way to convert M-length ByteString, Text or Vector into N-length one? For example, (a) converting byte array into array of their hex representations. ("abc" => "616263") (b) escaping some specific characters in string. ("a\bc" => "a\\bc") The only way I found is to use concatMap... Thanks, iquiw

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pandoc code bocks not working
by Walter De Jonge 16 Feb '10

16 Feb '10

http://johnmacfarlane.net/pandoc/README.html#delimited-code-blocks "Like regular code blocks, delimited code blocks must be separated from surrounding text by blank lines." goodluck walter

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Linguistic hair-splitting
by Andrew Coppin 16 Feb '10

16 Feb '10

Here's one for you to ponder. 7 is a number. 7 is an integer, and integers are numbers. 7 is not a field. 7 is an element of [at least one] field, but 7 itself is not a field. 7 is not a group. 7 is a member of the set of integers, but the set of integers is not a group either. The set of integers form a group when taken together with the addition operator. (And, actually, forms another, different, group when taken with the multiplication operator.) Now, here's the question: Is is correct to say that [3, 5, 8] is a monad? Is it correct to say that lists are a monad? Or would it be more correct to say that lists "form" a monad?

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Microsoft Research PhD Scholarship, University of Leeds
by David Duke 16 Feb '10

16 Feb '10

I'm pleased to announce a PhD Scholarship within the Visualization and VR group at Leeds, generously funded by Microsoft Research. We are seeking a student to investigate how visualization techniques can be further developed to understand and improve the performance of parallel Haskell programs running on multi-core CPUs. Closing date for applications is 22 March 2010. Could you please pass on this call to anyone who might be interested in applying. Further details are included below, and are also available on the web, at http://www.engineering.leeds.ac.uk/pg/studentships/duke.shtml thanks, David Duke PROJECT TITLE: "Visualizing Performance for Multicore Haskell" SUPERVISION: Dr. David Duke, School of Computing, University of Leeds, UK MRL CO-SUPERVISION: Dr. Satnam Singh Prof. Simon Peyton Jones Dr. Simon Marlow Microsoft Research Laboratory, Cambridge, UK OUTLINE: The GHC Haskell compiler now provides high-level abstractions that allow the programmer to benefit from multi-core CPUs. These abstractions support implicit parallelism - the programmer can indicate expressions that could usefully be evaluated in parallel, but is freed from concerns about when parallel evaluation takes place. However, it now becomes more difficult to isolate and resolve performance issues. Visualization of run-time behaviour can help. The Haskell community already have the benefit of a tool, ThreadScope, developed at Microsoft Research Cambridge (research.microsoft.com/en-us/labs/ Cambridge/) that provides insight into resource utilisation. However ThreadScope, like other performance visualization tools, presents the programmer with a view of low-level resources that differs from the level of abstraction at which Haskell programmers are encouraged to work. This studentship will investigate visualization techniques for linking high-level program abstractions with low-level runtime performance data. It should allow Haskell programmers to exploit parallelism more effectively. The student will join the Visualization and VR group at Leeds (www.comp.leeds.ac.uk/vvr) . Work on the PhD will involve: understanding how information about run-time resources can be extracted and visualized, and how programmers use these representations to reason about design and implementation choices; building or extending visualization tools; conducting user evaluations; modify components of the GHC compiler and runtime system. Work will be undertaken with support from the GHC/ ThreadScope team at Microsoft Research (Satnam Singh, Simon Peyton Jones, and Simon Marlow). At the discretion of Microsoft Research, the student may also be offered an internship at MRL Cambridge. FUNDING: The Scholarship provides a bursary of £20,000 per year for three years, covering fees and maintenance. A further £3000 per annum has been reserved for travel expenses to attend conferences and visits to Microsoft Research in Cambridge. Applicants from outside of the EU should note that higher student fees (currently £13,300) will necessarily reduce the amount available for maintenance. Home/EU fees stand at £3,390 currently. Microsoft Research will provide the successful candidate with a laptop equipped with a suite of software. ENTRY REQUIREMENTS: Applicants must hold a First-Class BSc (Hon) degree in Computer Science or equivalent. It is essential that applicants have excellent knowledge of functional programming and significant practical experience writing software in Haskell, Clean, or ML. Experience with GUI programming and/or information visualization is highly desirable. Knowledge of programming technologies, in particular compilers and implementation techniques for functional languages is also desirable. The position is open to students of all nationalities. SCHOOL OF COMPUTING, LEEDS: The School of Computing (www.comp.leeds.ac.uk) is among the 10 best Computing departments in the UK according to the 2008 Research Assessment Exercise (RAE). An impressive 80% of staff is rated internationally excellent or world leading. This clearly confirms the School’s position as one of the leading computing departments in the UK and a leader in the field internationally. APPLICATION PROCEDURE: Formal applications for research degree study must be made either online through the University website, or on the University’s application form. Detailed information of how to apply on line can be found at: www.leeds.ac.uk/students/apply_research.htm The paper application form is available at: www.leeds.ac.uk/rds/Admissions/Admis_home.htm Please return the completed application form to: Research Degrees & Scholarships Office, University of Leeds, LS2 9JT. Please provide all the documents required as soon as possible, either included with your paper application or sent directly to the School of Computing secretary (rsadmit(a)comp.leeds.ac.uk) if you apply online. Scanned copies are acceptable for a conditional offer; however you will need to provide originals or certified copies at registration. These will include your degree certificate(s), transcripts of marks achieved in previous degrees, plus evidence of English language qualifications if your first language is not English and you do not hold a degree from an English-speaking country. Please note, if you intend to send academic references we can only accept them if they are on official letter headed paper and contain an original signature and stamp; they must arrive in sealed envelopes. Alternatively, the School will contact your named academic referees directly. CLOSING DATE: Applications must be received by 22 March 2010. ACADEMIC CONTACT: For questions about the research topic, please contact Dr. David Duke, University of Leeds; Tel: +44 113 343 6800; Email: D.J.Duke(a)leeds.ac.uk; Web: www.comp.leeds.ac.uk/djd/

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on finding abstractions ...
by Günther Schmidt 16 Feb '10

16 Feb '10

Hello, I've got a problem, in short my haskell code sucks. While it does work and I do manage to use higher-orderish aspects quite extensively to make my code more concise it still is nowhere abstract, always concrete and thus always with lots of boilerplate. Oh I have gotten better compared to when I started but on the abstraction slope I'm still stuck. So fellows, what is the next stop on my road to enlightenment? I really think I need best to start from scratch. I think I'm sufficiently familiar now with most of Haskell's technicalities but how do I climb the ladder of abstraction? Günther

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Interpreting profiling results
by Patrick LeBoutillier 16 Feb '10

16 Feb '10

Hi, This question didn't get any replies on the beginners list, I thought I'd try it here... I've written (and improved using other solutions I've found on the net) a simple sudoku solver which I'm trying to profile. Here is the code: import Array import List (transpose, nub, (\\)) import Data.List data Sudoku = Sudoku { unit :: Int, cells :: Array (Int, Int) Int, holes :: [(Int, Int)] } cell :: Sudoku -> (Int, Int) -> Int cell s i = (cells s) ! i instance Read Sudoku where readsPrec _ s = [(Sudoku unit cells holes, "")] where unit = length . words . head . lines $ s cells = listArray ((1, 1), (unit, unit)) (map read . words $ s) holes = [ c | c <- indices cells, (cells ! c) == 0] instance Show Sudoku where show s = unlines [unwords [show $ cell s (x,y) | x <- [1 .. unit s]] | y <- [1 .. unit s]] genNums :: Sudoku -> (Int, Int) -> [Int] genNums s c@(i,j) = ([1 .. u] \\) . nub $ used where used = (row s u i j) ++ (col s u i j) ++ (square s sq u i j) u = unit s sq = truncate . sqrt . fromIntegral $ u row s u i j = [cell s (i, y) | y <- [1 .. u]] col s u i j = [cell s (x, j) | x <- [1 .. u]] square s sq u i j = [cell s (x, y) | y <- [1 .. u], x <- [1 .. u], f x i, f y j] where f a b = div (a-1) sq == div (b-1) sq solve :: Sudoku -> [Sudoku] solve s = case holes s of [] -> [s] (h:hs) -> do n <- genNums s h let s' = Sudoku (unit s) ((cells s) // [(h, n)]) hs solve s' main = print . head . solve . read =<< getContents When I compile as such: $ ghc -O2 --make Sudoku.hs -prof -auto-all -caf-all -fforce-recomp and run it on the following puzzle: 0 2 3 4 3 4 1 0 2 1 4 0 0 3 2 1 I get the following profiling report: Fri Jan 1 10:34 2010 Time and Allocation Profiling Report (Final) Sudoku +RTS -p -RTS total time = 0.00 secs (0 ticks @ 20 ms) total alloc = 165,728 bytes (excludes profiling overheads) COST CENTRE MODULE %time %alloc CAF GHC.Handle 0.0 10.7 CAF Text.Read.Lex 0.0 2.1 CAF GHC.Read 0.0 1.2 square Main 0.0 2.8 solve Main 0.0 1.3 show_aVx Main 0.0 3.7 readsPrec_aYF Main 0.0 60.6 main Main 0.0 9.6 genNums Main 0.0 5.0 cell Main 0.0 1.2 individual inherited COST CENTRE MODULE no. entries %time %alloc %time %alloc MAIN MAIN 1 0 0.0 0.3 0.0 100.0 main Main 186 1 0.0 9.6 0.0 85.6 show_aVx Main 196 2 0.0 3.7 0.0 3.7 cell Main 197 16 0.0 0.0 0.0 0.0 solve Main 188 5 0.0 1.3 0.0 11.8 genNums Main 189 8 0.0 5.0 0.0 10.4 square Main 194 88 0.0 2.8 0.0 3.2 cell Main 195 16 0.0 0.4 0.0 0.4 col Main 192 4 0.0 0.7 0.0 1.1 cell Main 193 16 0.0 0.4 0.0 0.4 row Main 190 4 0.0 0.7 0.0 1.1 cell Main 191 16 0.0 0.4 0.0 0.4 readsPrec_aYF Main 187 3 0.0 60.6 0.0 60.6 CAF GHC.Read 151 1 0.0 1.2 0.0 1.2 CAF Text.Read.Lex 144 8 0.0 2.1 0.0 2.1 CAF GHC.Handle 128 4 0.0 10.7 0.0 10.7 CAF GHC.Conc 127 1 0.0 0.0 0.0 0.0 Does the column 'entries' represent the number of times the function was called? If so, I don't understand how the 'square' function could be called 88 times when it's caller is only called 8 times. Same thing with 'genNums' (called 8 times, and solve called 5 times) What am I missing here? Patrick -- ===================== Patrick LeBoutillier Rosemère, Québec, Canada

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Undecidable instances with functional dependencies
by Henning Thielemann 16 Feb '10

16 Feb '10

I have the following class and instance class Register a r | a -> r where instance (Register a ra, Register b rb) => Register (a,b) (ra,rb) where and GHC refuses the instance because of violated Coverage Condition. I have more instances like instance Register Int8 (Reg Int8) where instance Register Word8 (Reg Word8) where and for the set of instances I plan, the instance resolution will always terminate. I remember that the term 'undecidable instance' is not fixed and may be relaxed if a more liberal condition can be found. Is there a place, say a Wiki page, where we can collect examples where we think that the current check of GHC is too restrictive?

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How to find unused exported symbols?
by John D. Ramsdell 16 Feb '10

16 Feb '10

I would like to find symbols exported from each module in a program that are not used outside the module. I'm worried my program is accumulating cruft. I'm looking for suggestions on how to find unused exported symbols. Do I have to analyse .hi files? Thanks in advance. John

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Darcs fundraising 2010 - success!
by Eric Kow 16 Feb '10

16 Feb '10

Hi everybody, Here's the final report on our Darcs 2010 fundraising effort. In a word, success! I wasn't sure we could pull it off, but thanks to all of your contributions, we reached our target of $2000. Thanks, everyone! We'll be using this money to fund travel expenses for our bi-annual Darcs hacking sprints. I'm looking forward to seeing what kind of impact this has, how much easier this makes it for us to bring our community together (literally). Finally, I think this would be a good time to call your attention to our new thank-you page <http://www.darcs.net/thanks.html>. This is just a small way for us to make a note of all the ways that you have helped the Darcs project, and how much we appreciate your contributions (your feedback, patches, support). Most recently, I've added a new section to this page, which makes a nod to some of ours larger donors. They also had some rather nice things to say about Darcs, so do have a look :-) Rah! Eric PS. Please let me know if you'd like to make a travel claim for ZuriHac -- Eric Kow <http://www.nltg.brighton.ac.uk/home/Eric.Kow> PGP Key ID: 08AC04F9

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IDL - compilers
by Günther Schmidt 16 Feb '10

16 Feb '10

Hi, are there any IDL compilers that can create Haskelk modules from header files or type-libs? Günther

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Two authors especially likely to be spammed.
by Jason Dusek 15 Feb '10

15 Feb '10

I recently discovered that many haskell-cafe mails are being dumped in my SPAM folder. A lot of them are from John Lato and Simon Marlow. I wonder if anyone else has experienced this? -- Jason Dusek

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How many "Haskell Engineer I/II/III"s are there?
by Jason Dusek 15 Feb '10

15 Feb '10

Although I'm fond of Haskell, in practice I am not a Haskell programmer -- I'm paid for Ruby and Bourne shell programming. Many of the jobs posted on this list end up being jobs for people who appreciate Haskell but will work in C# or O'Caml or some-such. I wonder how many people actually write Haskell, principally or exclusively, at work? -- Jason Dusek

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Virus alert while installing happstack
by Maciej Podgurski 15 Feb '10

15 Feb '10

Hi, I tried to install happstack via "cabal install happstack" on my WinXP system. While installation progress, my anti-virus software (Avira AntiVir) warned me about dll_hsc_make.exe and files_hsc_make.exe to be a Trojan horse called "TR/Dropper.Gen". It's a bit confusing to get a virus alert while installing Haskell packages. Has anyone experienced this problem? And can I trust these files to be harmless? Besh wishes, Maciej

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performance issue and HGL
by Vojtěch Knyttl 15 Feb '10

15 Feb '10

Hello, I've created a simple Mandelbrot set generator, using HGL, the source is viewable at: http://pastebin.dqd.cz/cUmg/ 1. The problem is, that it is very slow. It is obvious that what takes the most time is the "mandel" function computation. I have no idea, how it can be improved. 2. What is the easiest way of changing a color and plotting a pixel with it? Do I always have to "create a pen" for it? Isn't there a simple way? Already – using a line to plot a pixel is probably not the best way… Thanks

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running HGL on OSX
by Vojtěch Knyttl 15 Feb '10

15 Feb '10

Hello, I am having difficulties running HGL on Mac OSX, Snow Leopard. Here is what I've done: –– 1. Installed X11 for OSX ("About" dialog says: The X Window System, XQuartz 2.3.4 (xorg-server 1.4.2-apple45)) –– 2. Got X11 from Hackage – configured, built and installed – however, there where quite a lot of warnings: … [ 8 of 25] Compiling Graphics.X11.Xlib.Color ( Graphics/X11/Xlib/Color.hs, dist/build/Graphics/X11/Xlib/Color.o ) Graphics/X11/Xlib/Color.hs:38:0: Warning: The import of `Foreign.C.Types' is redundant except perhaps to import instances from `Foreign.C.Types' To import instances alone, use: import Foreign.C.Types() [ 9 of 25] Compiling Graphics.X11.Xlib.Font ( dist/build/Graphics/X11/Xlib/Font.hs, dist/build/Graphics/X11/Xlib/Font.o ) Graphics/X11/Xlib/Font.hsc:167:1: Warning: A do-notation statement discarded a result of type CInt. Suppress this warning by saying "_ <- xTextExtents font_struct c_string (fromIntegral nchars) direction_return font_ascent_return font_descent_return overall_return", or by using the flag -fno-warn-unused-do-bind … and so on. –– 3. Got HGL package, built and installed with some warnings like: … [ 1 of 27] Compiling Graphics.HGL.Internals.Flag ( Graphics/HGL/Internals/Flag.hs, dist/build/Graphics/HGL/Internals/Flag.o ) Graphics/HGL/Internals/Flag.hs:1:0: Warning: Module `Prelude' is deprecated: You are using the old package `base' version 3.x. Future GHC versions will not support base version 3.x. You should update your code to use the new base version 4.x. … –– Now, when I try to run simple program like: main = runGraphics $ withWindow_ "Hello World Window" (300, 200) $ \ w -> do drawInWindow w $ text (100, 100) "Hello World" drawInWindow w $ ellipse (100, 80) (200, 180) getKey w it says: $ ghci graphics.hs GHCi, version 6.12.1: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Loading package ffi-1.0 ... linking ... done. Ok, modules loaded: Main. Prelude Main> main Loading package syb-0.1.0.2 ... linking ... done. Loading package X11-1.5.0.0 ... can't load .so/.DLL for: X11 (dlopen(libX11.dylib, 9): image not found) Prelude Main> Just to precise, I have X11 running (it can be seen in the OSX dock) Thanks

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Using Cabal during development
by Limestraël 14 Feb '10

14 Feb '10

Cabal/cabal-install are good tools for distribution and installation, but I was wondering -- as I was starting to learn how to use Cabal -- how do usually Haskell developpers build their softwares (and especially medium or big libraries) while they are still developping them ? With cabal-install, by doing one 'cabal configure' once and 'cabal build' each time they have altered their code ? With only Cabal, through some 'runhaskell Setup.hs build's ? The point is that I am currently writing a binding for an SDL-like library called SFML. My project is now 55-file wide (and I will have to add some more), uses hsc2hs and has a little executable (for testing purposes) in which I add some code each time I add functionnalities to my binding. What I mean is that it would be a pain to have to compile it by hand whenever I add something to my code. Currently, I compile it by using a simple shell script, but it's a little bit lousy, I think. -- View this message in context: http://old.nabble.com/Using-Cabal-during-development-tp27515446p27515446.ht… Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.

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pandoc code bocks not working
by Anatoly Yakovenko 14 Feb '10

14 Feb '10

i am getting these failures with pandoc, or maybe i am not using markdown correctly 1. hello world ~~~~~~~~~ code block failed ~~~~~~~~~ * hello world ~~~~~~~~~ code block failed ~~~~~~~~~ * hello world clode block failed hello world =========== ~~~~~~~~~ code block ok ~~~~~~~~~

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ANN: wyvern, a Dragon Go Server "client"
by wagnerdm＠seas.upenn.edu 14 Feb '10

14 Feb '10

I've just done the first release of wyvern [1], a small program to play moves for you on the Dragon Go Server [2], along with point releases for two supporting libraries. On DGS, people play many games of go simultaneously, making only one move per day in each game (about). A commonly requested feature is the ability to specify several moves in advance, and have them be played automatically whenever the opponent logs in. Wyvern provides this capability, as well as the ability to program in advance several "branches" -- conditional on the opponent's move. Along with wyvern, I've been developing two supplementary libraries. The "dgs" library [3] is a very small wrapper around DGS' handy robot interface. The "sgf" library [4] is a parser for the SGF file format (used to store games of go) that strives to balance using the type system to enforce the construction of correct SGF trees against conveniently manipulating said trees. It was also something of an experiment for me in documentation writing -- I may have gone a little overboard. =) If, like me, you love to mix Haskell and go, I invite you to check out one or more of these and let me know what you think. ~d [1] http://dmwit.com/wyvern [2] http://www.dragongoserver.net/ [3] http://hackage.haskell.org/package/dgs [4] http://hackage.haskell.org/package/sgf

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Atom Examples
by Tom Hawkins 14 Feb '10

14 Feb '10

On Sun, Feb 14, 2010 at 1:30 AM, Yves Parès <limestrael(a)gmail.com> wrote: > > I've been interested in using Atom since I saw this: > http://blog.sw17ch.com/wordpress/?p=84 > However those samples are very outdated, do you have newer ones? Unfortunately, no. I wish I had the time to write Atom examples and tutorials, but I don't. So in lieu of a tutorial, here's a few modules we use on our real projects -- with limited documentation. Arbiter.hs: A general purpose non-preemptive arbiter than implements Lamport's bakery algorithm. We use this to arbitrate multiple software components that need to use the CAN protocol stacks for sending multi-packet messages. This is a good example that illustrates some of the benefits of atomic state transitions rules. What I find interesting is it works without any centralized arbiter logic; notice there are no rule declarations in mkArbiter. ECU.hs: This is the hardware abstraction layer to our ECU. Nothing too interesting, but a good example of how to wire Atom up to external C code. Note the ECU record includes a bunch of expressions (E types) and variables (V types). The expressions form the inputs, like ADCs and discrete inputs, and the mutable variables form the outputs, such as PWMs and discrete outputs. It also provides hooks to send and receive CAN messages. EVU.hs: The eVU is a little display mounted on the dash. It presents the driver with information such as charge pressure, mode settings, and fault conditions. The ECU talks to the eVU via the CAN bus. This is a good example because it illustrates a common object-oriented pattern we tend to use all over the place: the object contructor (mkEVU) creates some state variables, defines rules for stuff to do, and packages the state variables into an abstract type, or object (EVU); then methods operate on this object. In the case of EVU, the object constructor defines variables for the things the eVU displays, and it defines a rule to periodically send this information to the eVU device via CAN. And the methods set the various display elements such as the active fault code (setCode), the accumulator pressure (setCharge), and the active mode (setMode). Sensors.hs: Sensor processing, which takes data from the hardware abstraction layer (ECU.hs). One interesting feature is the oil temperature sensor computation. Based on a 1-D lookup table the 'lookup1D' function searches the table for the corresponding points and performs interpolation. In C, this probably would have been written as a for-loop that would compute the lookup on every sample. But because change in oil temperature is much slower than the sample rate of the system, we only need to search one row of the table every 50 samples or so (i.e. with rules 'below', 'above', 'next', and 'found'). This effectively spreads out the computation over many samples, thus lowering the processing latency of every sample. Doing this type of time-sharing in C would be tricky. But in Atom, it's trivial. One of the many ways Atom benefits hard realtime programming. I hope this helps. -Tom

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ANN: Dungeons of Wor - a largish FRP example and a fun game, all in one!
by Patai Gergely 14 Feb '10

14 Feb '10

Hello all, I just uploaded the first public version of Dungeons of Wor [1], a homage to the renowned three-decade-old arcade game, Wizard of Wor. While it makes a fine time killer if you have a few minutes to spare, it might be of special interest to the lost souls who are trying to figure out FRP. The game was programmed using the Simple version of the experimental branch of Elerea [2], which provides first-class discrete streams to describe time-varying quantities, and the main game logic is described as a composition of streams instead of a world state transformer. Developing in this manner was an interesting experience, and I'll write about it in more detail over the weekend. All the best, Gergely [1] http://hackage.haskell.org/package/dow [2] http://hackage.haskell.org/packages/archive/elerea/1.2.3/doc/html/FRP-Elere… -- http://www.fastmail.fm - The professional email service

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ANN: atom-1.0.0
by Tom Hawkins 14 Feb '10

14 Feb '10

Atom is a Haskell DSL for designing hard realtime embedded software. The 1.0 release is meant to indicate some level of stability; most of the core has been unchanged for quite some time. That said, there are a few interesting changes in 1.0. First the var' family of variable declarations (bool', word8', double', etc.) are no longer part of the Atom monad. For example: bool' :: Name -> V Bool This cleaned up quite a bit of code in our production design. This also made the randomization in Atom's unit testing framework monadless as well. The other significant change with 1.0 is all state variables are now packed into a hierarchical C structure that matches the hierarchy of the Atom design. Not only does this make the generated C a bit more legible, it is now possible to interface external C code directly to Atom's state variables and arrays. Prior to this change, all interfacing had to be done through var' declarations and action calls -- too often a messy process. To further aid interfacing to external code, Atom now generates a header file that exposes both the iterative function and the hierarchical state structure. -Tom http://hackage.haskell.org/package/atom

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hsWidgets: yet another GUI library
by Yuras Shumovich 13 Feb '10

13 Feb '10

Hello First of all, sorry my pure english... My aim was to prove that haskell GUI library can be: - pure: does not use any kind of mutable variables - statically typed: does not use existential types, Data.Dynamic, etc. - easy to use: simple things should be simple - easy to extend: writing new widgets should be as simple as possible The result is here: http://community.haskell.org/~YurasShumovich/hsWidgets/ Usage example: http://community.haskell.org/~YurasShumovich/hsWidgets/src/Test.hs The library is based on X11 and is tested on Linux and Mac OS. It is only an experiment in haskell GUI design, so it is mainly useless (currently only label, button and button with label are implemented) and looks ugly. Your comments and ideas are highly welcome.

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data-accessor-template-0.2.1.3 breaks cabal-install with ghc-6.12
by John Lato 13 Feb '10

13 Feb '10

Hello, I've recently run across an odd situation. I have a brand new install of GHC-6.12.1 (just did a fresh install of OSX 10.6), and am reinstalling some libraries. I've run into an unusual problem. I'm not sure if this would be considered a cabal bug or not, but I don't think it's a good situation. data-accessor-template depends upon template-haskell (>=2.2 && <2.4), unless built with the flag -ftemplate_2_4, in which case it depends upon template-haskell 2.4 (appropriate for ghc-6.12.1). The relevant lines of the .cabal file are: Flag template_2_4 description: Adapt to TemplateHaskell version of GHC-6.12 default: False If flag(template_2_4) Hs-Source-Dirs: src-5 Build-Depends: template-haskell >=2.4 && <2.5 Else Hs-Source-Dirs: src-3 Build-Depends: template-haskell >=2.2 && <2.4 I can install data-accessor-template when the template_2_4 flag is used, but then when I try to install a package that depends upon data-accessor-template cabal-install calculates the template-haskell >=2.2 && <2.4 dependency and attempts to fulfill it. Which fails at packedstring (can't find Data.Data in a hidden base package). I've included output from attempting to install Chart that demonstrates the behavior. Note that even though cabal-install sees data-accessor-template as installed, it attempts to reinstall it. John-Latos-MacBook:packages johnlato$ cabal install -v -O Chart In order, the following would be installed: packedstring-0.1.0.1 (new package) template-haskell-2.3.0.1 (new version) data-accessor-template-0.2.1.3 (reinstall) changes: template-haskell-2.4.0.0 -> 2.3.0.1 Chart-0.12 (new package) This affects everything down the dependency tree, notably Chart, criterion, and yi. I can work around this by specifying a previous version of data-accessor-template, but unfortunately I don't know how to address the real problem. Cheers, John

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haskell-src type inference algorithm?
by Job Vranish 13 Feb '10

13 Feb '10

Anyone know of a type inference utility that can run right on haskell-src types? or one that could be easily adapted? I want to be able to pass in an HsExp and get back an HsQualType. It doesn't have to be fancy, plain Haskell98 types would do. It wouldn't be to hard to make one myself, but I figured there might be one floating around already and it'd be a shame to write it twice :) Thanks, - Job

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Where are the Takusen sources?
by Jason Dagit 13 Feb '10

13 Feb '10

Hello, I wanted the takusen sources as I may want to add features. I looked on hackage and it lists this url for the repository: http://darcs.haskell.org/takusen I get a 404 on that URL. I checked Oleg's website: http://okmij.org/ftp/Haskell/misc.html#takusen And the links on that page have similar problems. I see that the 0.8.5 release has source on hackage, but I would prefer access to the full repository as I may want to send patches. Does anyone know what has happened to Takusen? Thanks, Jason

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ANN: hmatrix 0.8.3
by Alberto Ruiz 13 Feb '10

13 Feb '10

Hello, I have released a new version of hmatrix, a library for numeric computation based on LAPACK, BLAS and GSL. Recent developments include improved SVD functions, a simple ODE solver, easier OS/X installation (thanks to H. Apfelmus), and updated tutorial. hackage : http://hackage.haskell.org/package/hmatrix home page: http://code.haskell.org/hmatrix tutorial : http://code.haskell.org/hmatrix/hmatrix.pdf Any feedback is welcome! Alberto Ruiz

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haddock forgets parens in type sigs?
by Johannes Waldmann 12 Feb '10

12 Feb '10

The annotated type of "update" is missing parentheses: http://hackage.haskell.org/packages/archive/haskelldb/0.12/doc/html/Databas… (compare with the signature given in the source) - Best, J.W.

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Type arithmetic with ATs
by Andrew Coppin 12 Feb '10

12 Feb '10

OK, so I sat down today and tried this, but I can't figure out how. There are various examples of type-level arithmetic around the place. For example, http://www.haskell.org/haskellwiki/Type_arithmetic (This is THE first hit on Google, by the way. Haskell is apparently THAT popular!) But this does type arithmetic using functional dependencies; what I'm trying to figure out is how to do that with associated types. Any hints? (I know for a fact that other people have done this - rule 34 requires it.)

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Haskell IDEs on Windows; gtk2hs
by Alistair Bayley 12 Feb '10

12 Feb '10

I thought I'd try some of the Haskell IDEs: eclipsefp, leksah, and yi. So far, leksah requires gtk2hs (and apparently yi can use it too?), and the latest gtk2hs installer for Windows doesn't like the latest Haskell Platform, so I'm going to try building gtk2hs from source, unless anyone tells me that it's a waste of time. Building yi fails with: Yi\Prelude.hs:182:9: Duplicate instance declarations: instance Category Accessor.T -- Defined at Yi\Prelude.hs:182:9-38 instance Category Accessor.T -- Defined in data-accessor-0.2.1.2:Data.Accessor.Private cabal: Error: some packages failed to install: yi-0.6.1 failed during the building phase. The exception was: exit: ExitFailure 1 Presumably data-accessor has been updated, but yi has not? What is the easiest fix? Downgrade to an earlier version of data-accessor? So that just leaves eclipsefp. Still trying to figure out how to install eclipse plugins... Alistair

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Call for Copy: Monad.Reader Issue 16
by Brent Yorgey 12 Feb '10

12 Feb '10

Call for Copy: The Monad.Reader - Issue 16 ------------------------------------------ Whether you're an established academic or have only just started learning Haskell, if you have something to say, please consider writing an article for The Monad.Reader! The submission deadline for Issue 16 will be: **Friday, April 16, 2010** The Monad.Reader ~~~~~~~~~~~~~~~~ The Monad.Reader is a electronic magazine about all things Haskell. It is less formal than journal, but somehow more enduring than a wiki- page. There have been a wide variety of articles: exciting code fragments, intriguing puzzles, book reviews, tutorials, and even half-baked research ideas. Submission Details ~~~~~~~~~~~~~~~~~~ Get in touch with me if you intend to submit something -- the sooner you let me know what you're up to, the better. Please submit articles for the next issue to me by e-mail (byorgey at cis.upenn.edu) Articles should be written according to the guidelines available from http://themonadreader.wordpress.com/contributing/ Please submit your article in PDF, together with any source files you used. The sources will be released together with the magazine under a BSD license. If you would like to submit an article, but have trouble with LaTeX please let me know and we'll work something out.

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Re: Haskell-Cafe Digest, Vol 78, Issue 14
by John Lato 12 Feb '10

12 Feb '10

Edward's reply was quite good. I'll just try to fill in a few items he didn't address. > From: Maciej Piechotka <uzytkownik2(a)gmail.com> > > I read a lot about iteratee IO and it seemed very interesting > (Unfortunately it lacks tutorial). Especially features like 'no input > yet' in network programming (with lazy IO + parsec I run into problems > as it tried to evaluate the first response character before sending > output). > > I decided first write a simple program and then attempt write a Stream > implementation for parsec. > >> {-# LANGUAGE FlexibleInstances #-} >> {-# LANGUAGE MultiParamTypeClasses #-} >> import Data.Iteratee >> import Text.Parse >> >> data Buffer a = Buffer >> instance Monad m => Stream (Buffer a) (IterateeG [] a m) a where >> uncons Buffer = IterateeG loop >> where loop (Chunk []) = >> return $! Cont (IterateeG loop) Nothing >> loop (Chunk (x:xs)) = >> return $! Done (Just (x, Buffer)) >> (Chunk xs) >> loop (EOF Nothing) = >> return $! Done Nothing (EOF Nothing) >> loop (EOF (Just e)) = >> return $! throwErr e > > > 2. Is there any package which contains this stream definition? I believe this Stream instance is incorrect. According to the parsec-3.0.1 docs, "A Stream instance is responsible for maintaining the 'position within the stream' in the stream state s. This is trivial unless you are using the monad in a non-trivial way." This is necessary for referential integrity. That is, "uncons s" needs to always evaluate to the same result for the same 's'. Your Stream instance doesn't preserve this. As an example, > testIter = let b = Buffer in uncons b >> uncons b should be an iteratee that returns a "Maybe (t, buffer)" where t is the first element in the enumeration, but with your instance it will return the second. See http://inmachina.net/~jwlato/haskell/ParsecIteratee.hs for a valid Stream instance using iteratee. Also Gregory Collins recently posted an iteratee wrapper for Attoparsec to haskell-cafe. To my knowledge these are not yet in any packages, but hackage is vast. > > 3. Why Seek FileOffset is error message? Version 3 of iteratee is somewhat experimental, one of the ideas on trial is that of resumable exceptions. This framework is perfectly suited to handle control messages as well, which is why Seek is included as an error message. I don't want to make a major release just to fix this, but both error handling and control messages will undergo a substantial cleanup in the next major version. Included in this will be a proper separation between control messages and true exceptions, most likely based upon the extensible-exceptions framework. Cheers, John

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MissingH dropped QuickCheck dep
by John Goerzen 12 Feb '10

12 Feb '10

On Fri, Feb 12, 2010 at 08:45:09AM -0800, John MacFarlane wrote: > +++ thomas hartman [Feb 11 10 21:07 ]: > > gitit on hackage is still blocked because of dependency on missingh, > > which depends on qc1. Not an easy fix -- I couldn't figure out how to > > migrate testpack to qc2. > > > > However, missingh dependency was removed from gitit head > > > > http://github.com/jgm/gitit > > > > so that's good. > > No, gitit head still depends on MissingH, via ConfigFile. > > I imagine John will update MissingH to use QuickCheck2 soon... Hey guys, I took a look at MissingH and there was no need for the main library to depend on QuickCheck in the first place. It was only needed by the tests. So I've uploaded a new MissingH 1.1.0.2 to Hackage that drops that dep. That ought to solve it for you. -- John > > John > > >

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Infix and postfix operators in Parsec
by Xinyu Jiang 12 Feb '10

12 Feb '10

I'm writing a parser for a Haskell-style language, and when I need to use the same symbol for infix, prefix and postfix operators, the combinator "buildExpressionParser" seems not to work as intended. For example, in: (1)x + y (2)x + (3)+ x If I set the priority of the postfix version of "+" to be higher than the infix version, the parser cannot recognize (1), for it stops at the end of "x +". And if the priority of postfix "+" is lower, Parsec complains about (2) by returning an error message which expects something after "+". Is there some way to get over this problem, and let me be able to still benifit from the expression mechanism in Parsec. Or should I write these stuff from scratch? Thanks.

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Haskell RPC / Cluster
by Rick R 12 Feb '10

12 Feb '10

I am preparing to embark on some serious cluster oriented coding (high availability, monitoring, failover, etc). My primary concern is conforming to standards. I would also like to aid any existing project that fall under this scope. HackPar seems currently targeted towards HPC style clustering, but the page seems to hint at future work in the cloud/high-availability area. I was looking around for RPC libs for Haskell and stumbled across this http://github.com/mariusaeriksen/bert It implements BERT, which is based on Erlang's binary serialization protocol. It seems to have quite a bit of support. Does anyone know of any other RPC modules for Haskell? In addition, can anyone recommend other cluster oriented modules for monitoring, process management, etc? If those don't exist, can anyone recommend some standards off of which to base these? SNMP seems obvious (and daunting), any others? Thanks, Rick

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Re: [Haskell-cafe] HDBC convert [SqlValue] without muchos boilerplate
by Iain Barnett 12 Feb '10

12 Feb '10

On 11 Feb 2010, at 10:05, Vasyl Pasternak wrote: > > But fromSql function could convert everything to String, so you never > need to use `show`, just simply write > > convrow2 :: [SqlValue] -> String > convrow2 (x:xs) = foldl (\i j -> i ++ " | " ++ (fromSql j)) (fromSql x) xs > But, IMO, this is more readable version of your function: > > convrow2' :: [SqlValue] -> String > convrow2' = unwords . intersperse "|" . map fromSql > On 11 Feb 2010, at 10:06, Miguel Mitrofanov wrote: > > What if you just omit the "show" function? fromSql seems to be able to convert almost anything to String. Ok, thanks, that's a big help. I'm really glad to get rid off all that extra cruft I had there. I'd forgotten about intersperse, too. The new code works fine. Regards, Iain

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parallel and distributed haskell?
by Scott A. Waterman 12 Feb '10

12 Feb '10

It looks like there was a recent hackathon focusing on implementing distributed haskell. http://hackage.haskell.org/trac/ghc/wiki/HackPar I feel there is quite a bit of latent interest in the subject here, but relatively little active development (compared to erlang, clojure, etc.) Can anyone involved give a quick overview (or pointers to one)? It would be good to hear what directions people are taking, and why, and where it's going. Personally, I'd love to know the current thinking on a variety of subjects: * erlang-like port/actor implementations v. more implicit constructs * serialization * node failure/error handling * "grid" compatibility v. various ad-hoc cluster approaches. Anyone actively looking at this kind of question who would want to talk about it? Thanks, --ts

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Computer Camp for kids 13 - 15 years old in Colorado featuring Functional Reactive Programming
by John Peterson 12 Feb '10

12 Feb '10

Western State College in Colorado has a computer camp for kids aged 13 - 15. Although we don't use Haskell (it's Python on the inside) the underlying engine is Functional Reactive Programming. We use a 3-D game engine to explore more than just programming - we cover a lot of math and physics. We have a very unique camp - every day includes 3 - 4 hours of recreation in the area: rafting, rock climbing, kayaking, mountain biking. Our website is at http://western.edu/academics/computerscience/computer-camp.html The camp is the last week of June. See the website for further details. We're trying to get the software in releasable form - should be ready to go in a few months. This is the fourth year of our camp and FRP has been an ideal way to introduce novices to computing. John (PS - all recreational activities at our camp are approved by Simon PJ - http://haskell.org/haskellwiki/Simon_Has_Fun)

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ANN: hledger 0.8 released
by Simon Michael 12 Feb '10

12 Feb '10

hledger 0.8 is out! http://hledger.org http://hledger.org/MANUAL.html#installing Bug fixes, refactoring and Hi-Res Graphical Charts. (See Roman Cheplyaka's blog: http://www.reddit.com/r/haskell/comments/b0w0q/using_the_hledger_package_to…) Best - Simon Release notes: ...................... * parsing: in date=date2, use first date's year as a default for the second * add: ctrl-d doesn't work on windows, suggest ctrl-c instead * add: --no-new-accounts option disallows new accounts (Roman Cheplyaka) * add: re-use the previous transaction's date as default (Roman Cheplyaka) * add: a command-line argument now filters by account during history matching (Roman Cheplyaka) * chart: new command, generates balances pie chart (requires - fchart flag, gtk2hs) (Roman Cheplyaka, Simon Michael) * register: make reporting intervals honour a display expression (#18) * web: fix help link * web: use today as default when adding with a blank date * web: re-enable account/period fields, they seem to be fixed, along with file re-reading (#16) * web: get static files from the cabal data dir, or the current dir when using make (#13) * web: preserve encoding during add, assuming it's utf-8 (#15) * fix some non-utf8-aware file handling (#15) * filter ledger again for each command, not just once at program start * refactoring, clearer data types Stats: 62 days since last release, 2 contributors, 76 commits, 3464 lines of non-test code, 97 tests, 53% test coverage

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