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ghc 6.8.1 bug?
by SevenThunders 29 Nov '07

29 Nov '07

The good news is that my code compiles without error and much faster under ghc 6.8.1. The bad news is that there appear to be subtle bugs that did not occur when I compiled things under 6.6.1. One issue is that my code is somewhat complex and links into a C library as well. The new behavior is that under certain conditions a certain matrix inner product produces undefined floats, that should not be there. If the code is executed inside any function it fails but if the same code is reexecuted at the ghci prompt it works. Here is the gist of the code that I'm running main = do ... lots of computations and let clauses -- get a submatrix viewMatbotk wstart nsua su 1 suw -- get another submatrix viewMatbotk 0 nsua arrstart npaths sua -- complex non conjugated inner product (multiply the two submatrices) mulCFtF mprint If this is executed either in ghci as main or from a Dos prompt I get a matrix filled with bad values including a few that look like -1.#IND+1.87514i If I recompile everything in ghc-6.6.1 it works like charm. I make sure that I have deleted all the .o and .hi files. There is a dll that contains a C library I link to via running dlltool.exe. If I print out all the function inputs to the function viewMatbotk and then call them interactively in ghc 6.8.1 and call mulCFtF interactively it works correctly. both viewMatbotk and mulCFtF are C routines pulled in from the external library. I am at a complete loss how to debug this or how to pin down what exactly has changed between 6.6.1 and 6.8.1 that breaks this code so badly. This type of error stinks of some kind of memory issue, e.g. corrupted pointers. Any suggestions would be appreciated. Unfortunately the code base is rather involved and potentially proprietary so I can't publish all of the details. -- View this message in context: http://www.nabble.com/ghc-6.8.1-bug--tf4810375.html#a13763341 Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.

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Re: [Haskell-cafe] A tale of Project Euler
by Andrew Coppin 29 Nov '07

29 Nov '07

Michaeljohn Clement wrote: > Andrew Coppin wrote: > >> First, somebody else wrote this in C: >> >> int n = 2 , m , primesFound = 0; >> >> for( n=0;n < MAX_NUMBERS;n++ ) >> if( prime[n] ) >> { >> primesFound++; >> >> if( primesFound == 10001 ) >> cout << n << " is the 10001st prime." << endl; >> > > Um, I can't *believe* nobody else pointed this > out, but that isn't C, it's C++. > Really? How can you tell? Well anyway, the guy who wrote it said it's C. I suppose it was a simple oversight...

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Re: suggestion: add a .ehs file type
by Alex Young 29 Nov '07

29 Nov '07

Alex Jacobson wrote: > My original point (refined) was that I'd like a file extension (.ehs) > that defaults to including all extensions that don't change the meaning > of a .hs program but that may cause a small subset of them not to > compile (e.g. ones that use forall as a type variable, foreign as a > function, or 'd' as the result value of a list comprehension) > > This does not seem like a major change, does not break any existing > code, and has the advantage of making it really obvious when people are > going beyond haskell98. > It'll break all sorts of things when .ehs has to get merged into .hs the next time this conversation comes around, unless it's guaranteed that all .hs processors will eventually be upgraded to cope with .ehs semantics. I don't think anyone's arguing for that... -- Alex > -Alex- > > Simon Marlow wrote: >> I see, all you're saying is you'd like the default to be different. >> >> (That's not the same as saying "Extensions that change syntax are >> effectively declared by the use of that syntax", which is what you >> said earlier, BTW.) >> >> Well, we could change the default. I don't think it's a great idea >> personally - I think we should default to compiling whatever is the >> most recent standard, i.e. Haskell 98. But you're arguing that the >> proportion of Haskell 98 code that would fail to compile is relatively >> small; that might well be true. This isn't a decision we could take >> lightly, though. >> >> Furthermore, it's only something we could change in 6.10, by which >> time it is likely that we'll have a clearer idea of what Haskell' is, >> so there might well be a -fhaskell-prime flag (or it might even be the >> default). >> >> Cheers, >> Simon >> >> Alex Jacobson wrote: >>> >>> Simon, I think we've been trying to be too clever... >>> >>> The simple question is: for a given extension, what is the risk of >>> leaving it turned on by default? >>> >>> Clearly we don't want extensions turned on that causes code to >>> compile but with a different meaning. We may not want extensions >>> turned on that cause most reasonable code not to compile. >>> >>> But I would say neither risk is significant in the case of most >>> extensions. To use your examples: >>> >>> * FFI doesn't not cause h98 code to compile to a different meaning. >>> The worst case is that code that uses 'foreign' as a function name >>> doesn't compile. That seems okay in that more code probably uses FFI >>> than uses foreign as a function name and the user can apply a >>> language pragma to turn it off if really desired. >>> >>> * Existential types won't cause h98 code to compile with a different >>> meaning. The worst case is that code that uses 'forall' as a type >>> variable won't compile. That seems ok.... >>> >>> * TemplateHaskell also not compatible with h98. The worst case is >>> the loss "[d|" in list comprehensions. >>> >>> * MagicHash: Does not appear in the ToC or the Index of the user's >>> guide so should probably be turned off. I have no idea what it does. >>> >>> Note, in all cases where the extension is turned on by default, there >>> should be a language pragma to turn it off. >>> >>> >>> -Alex- >>> >>> Simon Marlow wrote: >>>> Alex Jacobson wrote: >>>>> >>>>> Simon, from what I can tell, with GHC 6.8.1, use of foreign as a >>>>> function name or forall as a type variable or leaving out a space >>>>> in a list-comprehension doesn't "parse differently" when the >>>>> relevant extensions are enabled, it causes a parse error. >>>> > >>>>> Extensions allow the same code to parse but with different meanings >>>>> need to be declared explicitly. But, extensions that are obvious >>>>> from syntax should be allowed to be declared simply from the use of >>>>> that syntax. >>>> >>>> So for the first example I gave, >>>> >>>> f x y = x 3# y >>>> >>>> the "MagicHash" extension is one that you'd require to be explicitly >>>> declared, because the expression parses both with and without the >>>> extension. >>>> >>>> Now, Let's take the Template Haskell example: >>>> >>>> f x = [d|d<-xs] >>>> >>>> So this is valid Haskell 98, but invalid H98+TH. You would >>>> therefore like this example to parse unambiguously as H98, correct? >>>> But in order to do that, our parser would need arbitrary lookahead: >>>> it can't tell whether the expression is legal H98+TH until it gets >>>> to the '<-' in this case. Certainly it's possible to implement this >>>> using a backtracking parser, but Haskell is supposed to be parsable >>>> with a shift-reduce parser such as the one GHC uses. Or we could >>>> try parsing the whole module with various combinations of extensions >>>> turned on or off, but I'm sure you can see the problems with that. >>>> >>>> So basically the problem is that you need a parser that parses a >>>> strict superset of Haskell98 - and that's hard to achieve. >>>> >>>> Cheers, >>>> Simon >>>> >>>>> I am not taking a position here on the merits of any extensions. >>>>> >>>>> -Alex- >>>>> >>>>> >>>>> Simon Marlow wrote: >>>>>> Alex Jacobson wrote: >>>>>> >>>>>>> Extensions that change syntax are effectively declared by the use >>>>>>> of that syntax. If you can parse the source, then you know which >>>>>>> extensions it uses. >>>>>> >>>>>> I thought we'd already established that this isn't possible. Here >>>>>> are some code fragments that parse differently depending on which >>>>>> extensions are enabled: >>>>>> >>>>>> f x y = x 3# y >>>>>> >>>>>> f x = [d|d<-xs] >>>>>> >>>>>> foreign x = x >>>>>> >>>>>> f :: forall -> forall -> forall >>>>>> >>>>>> You could argue that these syntax extensions are therefore badly >>>>>> designed, but that's a separate discussion. >>>>>> >>>>>> Cheers, >>>>>> Simon >>>>>> >>>>>>> -Alex- >>>>>>> >>>>>>> >>>>>>> Duncan Coutts wrote: >>>>>>>> On Fri, 2007-11-23 at 16:26 +0100, Wolfgang Jeltsch wrote: >>>>>>>>> Am Freitag, 23. November 2007 03:37 schrieben Sie: >>>>>>>>>> On Fri, 2007-11-23 at 01:50 +0100, Wolfgang Jeltsch wrote: >>>>>>>>>>> Dont’t just think in terms of single modules. If I have a >>>>>>>>>>> Cabal package, >>>>>>>>>>> I can declare used extensions in the Cabal file. A user can >>>>>>>>>>> decide not >>>>>>>>>>> to start building at all if he/she sees that the package uses an >>>>>>>>>>> extension unsupported by the compiler. >>>>>>>>>> Indeed. In theory Cabal checks all the extensions declared to >>>>>>>>>> be used by >>>>>>>>>> the package are supported by the selected compiler. In >>>>>>>>>> practise I'm not >>>>>>>>>> sure how well it does this or what kind of error message we get. >>>>>>>> >>>>>>>>> The problem is, of course, that you are not forced to specify >>>>>>>>> all used extensions in the Cabal file since you can still use >>>>>>>>> language pragmas. Sometimes it is even desirable to use >>>>>>>>> LANGUAGE pragmas instead of information in the Cabal file. For >>>>>>>>> example, even if some modules use undecidable instances, I >>>>>>>>> might not want all modules of the package to be compiled with >>>>>>>>> -XUndecidableInstances since this could hide problems with my >>>>>>>>> class structure. >>>>>>>> >>>>>>>> Our tentative plan there is to separate the extensions field >>>>>>>> into those >>>>>>>> used in some module, and those applied by cabal to every module. >>>>>>>> So that >>>>>>>> would allow you to specify a feature in one file but not all, while >>>>>>>> still declaring to the outside world that the package uses the >>>>>>>> feature. >>>>>>>> >>>>>>>> As for enforcing that, that may come almost for free when we get >>>>>>>> dependency chasing as we'll be looking for imports anyway. It >>>>>>>> shouldn't >>>>>>>> be much harder to look for language pragmas too. >>>>>>>> >>>>>>>> Duncan >>>>>>>> _______________________________________________ >>>>>>>> Glasgow-haskell-users mailing list >>>>>>>> Glasgow-haskell-users(a)haskell.org >>>>>>>> http://www.haskell.org/mailman/listinfo/glasgow-haskell-users >>>>>>> >>>>>>> _______________________________________________ >>>>>>> Glasgow-haskell-users mailing list >>>>>>> Glasgow-haskell-users(a)haskell.org >>>>>>> http://www.haskell.org/mailman/listinfo/glasgow-haskell-users >>>>>>> >>>>> >>>>> >>> >>> > > _______________________________________________ > Glasgow-haskell-users mailing list > Glasgow-haskell-users(a)haskell.org > http://www.haskell.org/mailman/listinfo/glasgow-haskell-users

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nbody (my own attempt) and performance problems
by Ryan Dickie 29 Nov '07

29 Nov '07

I thought it would be a nice exercise (and a good learning experience) to try and solve the nbody problem from the debian language shootout. Unfortunately, my code sucks. There is a massive space leak and performance is even worse. On the bright side, my implementation is purely functional. My twist: I manually unrolled a few loops from the C++ version. I believe that most of my performance problems stem from my abuse of tuple. The bodies are passed as a tuple of planets, a planet is a tuple of (position, velocity, mass) and the vectors position and velocity are also tuples of type double. My lame justification for that is to make it nice and handy to pass data around. Any tips would be greatly appreciated. --ryan

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Downside of -fglasgow-extensions
by manu 29 Nov '07

29 Nov '07

Hello, I'm trying to build diverse packages from Hackage with ghc 6.8.1, they usually fail to build because of missing language extensions. Sometimes I am unable to determine the proper name of the extension missing in .cabal I tend to slap {- #OPTIONS -fglasgow-exts #-} at the top of the troublesome file. It works, but out of curiosity, what is the downside of such an approach ? (bigger executables ?) Thanks M

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RFI: HDBC-1.1.3 build error
by Jim Stuttard 28 Nov '07

28 Nov '07

ubuntu gutsy ghc-6.8.1 HDBC-1.1.3$ runghc Setup.lhs build Preprocessing library HDBC-1.1.3... Building HDBC-1.1.3... [3 of 6] Compiling Database.HDBC.Types ( Database/HDBC/Types.hs, dist/build/Database/HDBC/Types.o ) Database/HDBC/Types.hs:208:0: Illegal polymorphic or qualified type: forall conn. (IConnection conn) => conn -> b In the type signature for `withWConn': withWConn :: forall b. ConnWrapper -> (forall conn. (IConnection conn) => conn -> b) -> b TIA

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Why aren't Float and Double Bounded?
by Jason Dusek 28 Nov '07

28 Nov '07

Among numeric types, it seems that only integer types are Bounded. -- _jsn

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A tale of Project Euler
by Andrew Coppin 28 Nov '07

28 Nov '07

Hi guys. Somebody just introduced me to a thing called "Project Euler". I gather it's well known around here... Anyway, I was a little bit concerned about problem #7. The problem is basically "figure out what the 10,001st prime number is". Consider the following two programs for solving this: First, somebody else wrote this in C: int n = 2 , m , primesFound = 0; for( n=0;n < MAX_NUMBERS;n++ ) if( prime[n] ) { primesFound++; if( primesFound == 10001 ) cout << n << " is the 10001st prime." << endl; for(m=2*n;m<MAX_NUMBERS;m+=n) prime[m]=false; } Second, my implementation in Haskell: primes :: [Integer] primes = seive [2..] where seive (p:xs) = p : seive (filter (\x -> x `mod` p > 0) xs) main = print (primes !! 10000) Well, we know who's winning the beauty contest. But here's the worrying thing: C program: 0.016 seconds Haskell program: 41 seconds Eeeps! o_O That's Not Good(tm). Replacing "primes :: [Integer]" with "primes :: [Word32]" speeds the Haskell version up to 18 seconds, which is much faster but still a joke compared to C. Running the Haskell code on a 2.2 GHz AMD Athlon64 X2 instead of a 1.5 GHz AMD Athlon drops the execution time down to 3 seconds. (So clearly the box I was using in my lunch break at work is *seriously* slow... presumably the PC running the C code isn't.) So, now I have a Haskell version that's "only" several hundred times slower. Neither program is especially optimised, yet the C version is drastically faster. This makes me sad. :-( By the way... I tried using Data.List.Stream instead. This made the program about 40% slower. I also tried both -fasm and -fvia-c. The difference was statistically insignificant. (Hey guys, nice work on the native codegen!) The difference in compilation speed was fairly drastic though, needless to say. (The machine is kinda low on RAM, so trying to call GCC makes it thrash like hell. So does linking, actually...) Also, I'm stuck with problem #10. (Find the sum of all primes less than 1 million.) I've let the program run for well over 15 minutes, and still no answer is forthcomming. It's implemented using the same primes function as above, with a simple filter and sum. (The type has to be changed to [Word64] to avoid overflowing the result though.) The other guy claims to have a C solution that takes 12 ms. There's a hell of a difference between 12 ms and over half an hour...(!) Clearly something is horribly wrong here. Uh... help?

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Pb builind hdbc-sqlite3 (the end)
by manu 28 Nov '07

28 Nov '07

Hello I should think a bit before posting to the list, sorry for the pollution ! this error : Database/HDBC/Sqlite3/Utils.hsc:74:8: parse error on input `import' manu:/Volumes/data/Downloads/HDBC/hdbc-sqlite3 manu$ can be avoided by adding ForeignFunctionInterface to the extensions in the .cabal file I also had to add EmptyDataDecls to the extensions and since adding PatternSignatures cause a parse error (see http:// hackage.haskell.org/trac/hackage/attachment/ticket/160/cabal-1.2.0- extensions.patch) I added this pragma {-# LANGUAGE PatternSignatures #-} at the top of Statement.hsc and Connection.hs It did build ! Victory ! M

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Pb builind hdbc-sqlite3 (suite)
by manu 28 Nov '07

28 Nov '07

Hello, Still trying to build hdbc-sqlite3 it appears that the hdbc-sqlite3 package on Hackage is missing the C header file It is included with the hdbc-sqlite3 package found at http:// software.complete.org/hdbc-sqlite3/downloads however. Now I have another pb : >>> Building HDBC-sqlite3-1.1.3.0... [3 of 7] Compiling Database.HDBC.Sqlite3.Utils ( dist/build/Database/ HDBC/Sqlite3/Utils.hs, dist/build/Database/HDBC/Sqlite3/Utils.o ) Database/HDBC/Sqlite3/Utils.hsc:74:8: parse error on input `import' manu:/Volumes/data/Downloads/HDBC/hdbc-sqlite3 manu$ >>> line 74 is : foreign import ccall unsafe "sqlite3.h sqlite3_errmsg" I've checked and I have a sqlite3.h file in /usr/include what is this "parse error on input `import'" about ??? Thanks M

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Re: is there a more concise way to generate helper functions for a datatype built on records?
by Benedikt Huber 28 Nov '07

28 Nov '07

Neil Mitchell wrote: > Hi > > Some of these can be automatically derived by the Data.Derive tool... > The derivations Set, Is, From, Has, LazySet all look useful. > ... > > On Nov 24, 2007 4:01 PM, Thomas Hartman <tphyahoo(a)gmail.com> wrote: >> I think I'm running into more or less the same issue discussed at >> >> http://bloggablea.wordpress.com/2007/04/24/haskell-records-considered-grung… >> >> Just wondering if I missed anything, or if any of the ideas >> considering better records setter/getters have been implemented in the >> meantime. Hi, the Ref deriviation (included in Data.Derive) seems to be a good way to solve some aspects of this problem; I have some questions on my own though. Here is a working example of updating the two player's state in the pong game: > {-# OPTIONS -cpp #-} > {-# OPTIONS_DERIVE --output=file.h #-} > module Main where > import Control.Arrow > #include "file.h" Refs as in (http://www.haskell.org/pipermail/haskell-cafe/2007-June/026477.html ): > type Upd a = a -> a > data Ref cx t > = Ref { select :: cx -> t , update :: Upd t -> Upd cx } > (@.) :: Ref a b -> Ref b c -> Ref a c > a @. b > = Ref { select = select b . select a, > update = update a . update b } The game model: > data Object2D > = Object2D { x :: Double, y :: Double } deriving (Show {-! Ref !-}) > data Player > = Player { points :: Int, pos :: Object2D } deriving (Show {-! Ref !-}) > data Game > = Game { p1 :: Player, p2 :: Player, ball :: Object2D } deriving (Show {-! Ref !-}) > sampleGame :: Game > sampleGame = Game { p1 = Player 0 (Object2D 5 0), p2 = Player 0 (Object2D 5 10), ball = Object2D 5 5 } Game update proceeds in several steps, we now consider the first one: Updating the 2 player's position - this happens, at least conceptually, *in paralell* (for example: both players might be aloud to have a look at the other players position in the last turn, but not at the updated position). Here's the update for one player: > updatePlayerPos :: Bool -> Upd Player > updatePlayerPos moveRight > = update (refPos @. refX) $ > case moveRight of > True -> ((min 10) . (+1)) > False -> ((max 0) . (+(-1))) If sequential update is ok for us, the game state update is simply: > updatePositions :: Bool -> Bool -> Upd Game > updatePositions move1 move2 = update refP1 (updatePlayerPos move1) . update refP2 (updatePlayerPos move2) To get it *actually* work in parallel we have to create a new reference for both players: > refPlayers :: Ref Game (Player,Player) > refPlayers = Ref { select = select refP1 &&& select refP2, > update = \pu g -> let (p1',p2') = pu (p1 g, p2 g) in g { p1 = p1', p2 = p2' } } While the select part of the Ref is expressed using &&&, I don't know how the paralell update can be expressed in terms of combinators. Any hints ? Now, the game state update in the parallel version is easy. Note that it would also be possible now to take one player's position into account when updating the other player's position: > updatePositionsPar move1 move2 = (update refPlayers) $ updatePlayerPos move1 *** updatePlayerPos move2 So, the Ref deriviation is really nice for sequential updates; paralell updates on the other hand need some work. Furthermore, I don't really know how well Refs work if updates need information on other parts of the state without modifying it. (e.g. the AI player needs to know where the ball is, but does not modify the ball). I'd really appreciate if anyone has some additional clues. thanks, benedikt

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Pb building HDBC-sqlite3
by manu 28 Nov '07

28 Nov '07

Hello still, trying to use a database with ghc 6.8.1 - patience running low however :) I now have troubles installing HDBC-sqlite3 the build fails like so : >>>>> $ runhaskell Setup.lhs build Preprocessing library HDBC-sqlite3-1.1.3.0... Utils.hsc:31:33: error: hdbc-sqlite3-helper.h: No such file or directory Utils.hsc: In function ‘main’: Utils.hsc:70:0: error: parse error before ‘finalizeonce’ compiling dist/build/Database/HDBC/Sqlite3/Utils_hsc_make.c failed command was: /usr/local/bin/ghc -c -package base-3.0.0.0 -package mtl-1.1.0.0 -package HDBC-1.1.3 -I. dist/build/Database/HDBC/Sqlite3/ Utils_hsc_make.c -o dist/build/Database/HDBC/Sqlite3/Utils_hsc_make.o >>>>> the hdbc-sqlite3-helper.h file is nowhere to be found on my system should it be part of the package ? Thanks M

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About garbage collecting
by Maurício 28 Nov '07

28 Nov '07

Hi, If available memory is low, is the garbage collector going to eliminate data that is still referenced, but it knows it can be recalculated when needed? Thanks, Maurício

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Building MissingH on Windows
by nionita＠lycos.de 28 Nov '07

28 Nov '07

Hi, I'm trying to build MissingH (0.18.6) on Windows, but it looks like (probably because of changes in Cabal) the Setup.hs is broken. Im using GHC 6.8.1. Following message: $ runhaskell Setup.hs configure Setup.hs:19:35: Couldn't match expected type `(Either GenericPackageDescription PackageDescription, HookedBuildInfo)' against inferred type `PackageDescription' In the first argument of `(confHook defaultUserHooks)', namely `mydescrip' In the expression: let mydescrip = case os of "mingw32" -> ... _ -> ... in (confHook defaultUserHooks) mydescrip flags In the definition of `customConfHook': customConfHook descrip flags = let mydescrip = ... in (confHook defaultUserHooks) mydescrip flags I'm new to Cabal and I couldn't see a fast way to fix it. Thanks, Nicu

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building a Haskell package on cygwin
by Galchin Vasili 28 Nov '07

28 Nov '07

Hello, What is involved in building a package on cygwin? Kind regards, Vasya

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about GADTs on ghci
by Yu-Teh Shen 28 Nov '07

28 Nov '07

i have seen the documents in http://www.haskell.org/haskellwiki/Generalised_algebraic_datatype but i can not run the following code on ghci ex: data Term x where K :: Term (a -> b -> a) S :: Term ((a -> b -> c) -> (a -> b) -> a -> c) Const :: a -> Term a (:@) :: Term (a -> b) -> (Term a) -> Term b infixl 6 :@ could any tell me how to run the code? Thanks a lot

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Re: [Haskell-cafe] A tale of three shootout entries
by Ryan Dickie 28 Nov '07

28 Nov '07

Oops forgot to hit reply-to-all.. resending.. N-body is looking good. I am running and amd64 3000+ on ghc 6.8.1. The debian shootout is showing a huge gap between ghc 6.6 and g++ but I am not seeing that gap. One concern though is that the code doesn't look very "haskellish". So much pointer manip. For the nbody c++ code I am getting: -0.169075164 -0.169031665 real 0m11.168s user 0m10.891s sys 0m0.043s and for the nbody haskell code I am getting: -0.169075164 -0.169031665 real 0m11.595s user 0m11.422s sys 0m0.044s On Nov 26, 2007 8:21 PM, Don Stewart <dons(a)galois.com> wrote: > s.clover: > > In some spare time over the holidays I cooked up three shootout > > entries, for Fasta, the Meteor Contest, and Reverse Complement. I > > Yay! > > > First up is the meteor-contest entry. > > > > http://shootout.alioth.debian.org/gp4/benchmark.php? > > test=meteor&lang=ghc&id=5 > > > > This is the clear win of the bunch, with significantly improved time > > thanks to its translation of the better algorithm from Clean. > > Well done! Though looks like we'll have to follow the C++ implementation > to be really competitive. > > > Next is reverse-complement. > > > > http://shootout.alioth.debian.org/gp4/benchmark.php ? > > test=revcomp&lang=ghc&id=3 > > Very good. I'm glad someone looked at that, since the old code was > moderately naive (first bytestring effort). > > > Finally, there's fasta. > > > > http://shootout.alioth.debian.org/gp4/benchmark.php? > > test=fasta&lang=ghc&id=2 > > Yeah, we should do something better here. Hmm. > > > p.s. It looks like they've depreciated chameneos in favor of a new > > version, chameneos-redux. As this was one of the places Haskell > > really rocked the competition, it would probably be worth updating > > Definitely. I note also we're beating Erlang on the new thread-ring > benchmark too, > > http://shootout.alioth.debian.org/gp4/benchmark.php?test=threadring&lang=all > > > the Haskell entry for the new benchmark. Also, the n-bodies benchmark > > seems like another that could be much improved. > > Yeah, that's a hard one. > > -- Don > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe >

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the ability to talk to POSIX device drivers
by Galchin Vasili 28 Nov '07

28 Nov '07

Hello, I saw somewhere that in one of the Haskell libraries there is support to open, read, write, ioctl, etc. to POSIX drivers, but I don't see in the Haskell Report. ?? Kind regards, Vasili

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data-parallel prime sieve?
by Adam Megacz 28 Nov '07

28 Nov '07

Hello, Can anybody point me to a data-parallel implementation of the prime sieve -- or any other prime number enumerator? NESL/Nepal/DP-Haskell code would be nice, but anything fitting the data parallel model will do. I'm particularly looking for a solution that doesn't wind up being dominated by the I/O latency between the serial and parallel contexts -- especially as you get towards higher numbers where the distance between the primes becomes a significant fraction of the amount of storage in the parallel context. I found pseudocode for such a program in a set of NESL slides from 1995 (before it was released) as well as a paper about a CM-2 implementation, but neither is quite satisfactory. Thanks! - a -- PGP/GPG: 5C9F F366 C9CF 2145 E770 B1B8 EFB1 462D A146 C380

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St. Petersburg Game
by manolo＠austrohungaro.com 28 Nov '07

28 Nov '07

Hello, I'm trying to program an implementation of the St. Petersburg game in Haskell. There is a coin toss implied, and the random-number generation is driving me quite mad. So far, I've tried this: import Random increment :: Int -> Int increment b = b + 1 main = do let b = 0 let c = randomRIO (1,2) until (c == 1) increment b return b This is intended to print the number of consecutive heads (i.e., 2) before the first tail, but I get the following error: ERROR "StPetersburg.hs":8 - Type error in application *** Expression : until (c == 1) increment b *** Term : c == 1 *** Type : Bool *** Does not match : Int -> Bool I don't really see what's going on, so any help will be more than welcome. I hope this is a suitable question for the Haskell Café list. I'm using Hugs in an Ubuntu box, in case that should be useful. Thanks, Manolo

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return in Monad class necessary?
by Henning Thielemann 27 Nov '07

27 Nov '07

I wonder whether it is a typical mistake of beginners to write 'return' within a do-block (that is, not at the end) and if it is possible to avoid this mistake by clever typing. In a proper monad 'return' can be fused with subsequent actions, and thus it is not necessary within a sequence of actions. However, although sensible, 'return' is also not required at the end of a block. Has someone already thought about a replacement for monads?

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Browser action and new http library
by bbrown 27 Nov '07

27 Nov '07

I am trying to use the HTTP library 3001 for ghc 6.8 and cant figure out how to use a proxy to do a GET request as I am behind a proxy server. My thinking is that I could use the setProxy method it looks like it returns a BrowserAction? What do I do with that. Here is the current code (I havent really used the setProxy yet). -- -- HTTP LIBRARY version: HTTP-3001.0.2 import Data.Char (intToDigit) import Network.HTTP import Network.URI import Network.Browser (defaultGETRequest) import System.Environment (getArgs) import System.Exit (exitFailure) import System.IO (hPutStrLn, stderr) main = do args <- getArgs case args of [addr] -> case parseURI addr of Nothing -> err "Could not parse URI" Just uri -> do cont <- get uri putStr cont _ -> err "Usage: lman <url>" err :: String -> IO a err msg = do hPutStrLn stderr msg exitFailure get :: URI -> IO String get uri = do eresp <- simpleHTTP (defaultGETRequest uri) resp <- handleErr (err . show) eresp case rspCode resp of (2,0,0) -> return (rspBody resp) _ -> err (httpError resp) where showRspCode (a,b,c) = map intToDigit [a,b,c] httpError resp = showRspCode (rspCode resp) ++ " " ++ rspReason resp -- -- Handle Connection Errors handleErr :: Monad m => (ConnError -> m a) -> Either ConnError a -> m a handleErr h (Left e) = h e handleErr _ (Right v) = return v -- End of File -- Berlin Brown [berlin dot brown at gmail dot com] http://botspiritcompany.com/botlist/?

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Announce: strict-concurrency
by Don Stewart 27 Nov '07

27 Nov '07

While writing some multi-core concurrent code I needed more precise control over which thread evaluated particular expressions. The default concurrent types, MVar and Chan, are lazy, and sometimes not suitable. The little package, http://hackage.haskell.org/cgi-bin/hackage-scripts/package/strict-concurren… Provies the MVar type, but with strict putMVar by default, and an element-strict Chan type. For some applications, these stricter types can yield improved time and space use. (For others, they can make things worse) The strict channel type in particular seems useful, as it can be used to force worker threads to evaluate to WHNF before returning values to a driver thread. Enjoy, Don

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Pretty-printing peg solitaire boards
by Maurício 27 Nov '07

27 Nov '07

Hi, I'm trying to pretty-print (with Text . PrettyPrint . HughesPJ) a set of peg solitaire boards. No matter what I try, I always get this: 00# 00# 0000#00 0000000 0000000 000 000 : 00# 00# 0000000 0000000 0000000 000 000 but what I really want is this: 00# 00# 00# 00# 0000#00 0000000 0000000 : 0000000 0000000 000 000 000 000 000 What I'm I doing wrong? When I have two boards a,b::Doc, I'm composing them with a <+> colon <+> b and rendering them with just 'render'. Should I try something else? Thanks, Maurício

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Re: [Haskell-cafe] New demo/test program for Yhc Javascript backend
by Thomas Hartman 27 Nov '07

27 Nov '07

Fair enough, I can wait for a couple of days. You might want to fix thartman@none:~/haskell-installs/yhc-install/yhc/src/translator/js/test>darcs whatsnew { hunk ./src/translator/js/test/Makefile 12 - $(YHC) -includes ../lib/haskell -linkcore $< + $(YHC) --includes ../lib/haskell --linkcore $< } immediately though. This is the only makefile for the javascript stuff in the repo, and it doesn't work because of - instead of --. Given your darcs log message that the javascript compiler would be broken I initially assumed that was the reason and not a flags change. More questions. So okay, it builds, I have Test1.html. It's a blank file with a bunch of javascript. I have firebug, so I can ask execute stuff in the javascript console. But I can't figure out what to execute. factorial isn't there, nor sumlst... none of the interesting looking functions? So what is this supposed to do? And can I change the makefile so that at least it generates javascript where I can execute the interesting functions in the firebug console? thomas. 2007/11/26, Dimitry Golubovsky <golubovsky(a)gmail.com>: > Thomas, > > OK, let's try to get on the same page regarding where the project is. > > The Javascript generator is maybe not optimal, but it works. > > DOM bindings are generated from W3C's IDL files, so everything DOM > provides may be used by Haskell programs, whether in CPS notation, or > monadic, this will become clear, which form to use, in the near > future. > > The recent HsWTKDemo works well in major browsers (FF, MSIE, Opera) > except for Safari, but this is probably a hard case due to the lack of > debugging information. > > If you look at its source http://darcs.haskell.org/yhc/web/jsdemos/HsWTKDemo.hs > > (no, you cannot compile it at the moment because it is plain CPS) you > may see some stuff related to static page layout definition in > declarative way (look for upcntW, factW, etc.) This part is almost > finalized wrt notation. What's left undecided is whether to use plain > CPS notation, or monadic notation for parts of the code that involve > imperative stuff (see e. g. updateD function where node's children are > replaced in order to update what's displayed). > > This all works perfectly in plain CPS. Understanding that nowadays > Monads are mainstream, I am trying to adopt monadic notation based on > the Cont monad instead of plain CPS. I ran one example (EchoM) on MSIE > and noticed memory leaks on each user's action. However when the page > is unloaded, MSIE shrinks in size which is a good sign. I think I know > where the cause is, tonight I'll try to fix it. If unsuccessful, I'll > probably unroll all monadic changes. > > Next steps are: > > 1. Finalize the code notation for static layout and imperative part > and check the base library into the Yhc repo > > 2. Generate haddock documentation > > 3. Write a better documentation for developers > > 4. Set up a web service that would allow everybody to submit their > Haskell source and generate HTML page with Javascript in response; > this I think can be done based on the hpaste program (backed by > Happs). > > Just for now, you have to wait a couple days while I am straightening > the monadic thing out. I'd appreciate if you look at the code of > HsWTKDemo and give me your impressions about notation, etc. > > Thank you. > > -- > Dimitry Golubovsky > > Anywhere on the Web >

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idea for ycr2js demo, actually meant for an in-house project. is this realistic?
by Thomas Hartman 27 Nov '07

27 Nov '07

As I mentioned in a previous post, I've been spending quite some time trying to get live with ycr2js because there's a project it would be useful for for my day job, as well as making another nice demo to add to the list. Basically, I have some functionality that does client-side filtering of large html tables. It's pretty smart -- it can filter on multiple columns, and the filter can be any javascript expression from String -> Bool (to use haskell terminology in a javascript context). The filter works by hiding rows that don't match the filter; it's built on mochikit. Unfortunately this is rather ugly from the user's perspective. You have to type something like x.match("my string") into the search string or (x > 5 && x < 7) where x is some variable buried in the javascript. I would like for the user to be able to enter search criteria in a more intuitive "google" style =skittles or (=~"mr. goodbar" and =~"15 grams") so you need a parser that takes the search criteria and converts it into a function from (String -> Bool) This parser is relatively easy to build in haskell; I built it. It's surely also doable in javascript, but not as nicely, easily, and cleanly, and being a better haskell than javascript programmer as well, I would rather generate the javascript from haskell. So at any rate what I have is -- parser from String -> (String -> Bool) (haskell) -- working html/javascript built on mochikit that filters a multicolumn table with multiple filter expressions. There is a function here that takes a string and returns a bool, but it's icky, doesn't recognize quoted strings, doesn't recognize boolean and/or or parentheses. I want to replace it with a function generated from haskell that does all of these things. What I need is to combine these two components. I'll try and post some minimal source code for the parser and the javascript/mochikit stuff soon, and if this problem is tractable it can become another example for ycr2js. A possible reason why this wouldn't work is that when you're using the ycr2js stuff, *everything* has to be generated; it doesn't play well plugging in an existing javascript function with a generated one. I'd be surprised if that was the case, but since I haven't actually successfully generated any code yet i guess anything possible. At any rate, if this sort of thing could cause issues please someone in the know give me fair warning. thomas.

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Re: [Haskell-cafe] New demo/test program for Yhc Javascript backend
by Thomas Hartman 27 Nov '07

27 Nov '07

2007/11/26, Dimitry Golubovsky <golubovsky(a)gmail.com>: > Thomas, > > All published examples (source, html) go into web/jsdemos subdirectory > (from the root of the Yhc repo source tree). right; it would be nice to have a makefile (or makefiles) there that works out of the box, rather than relying on the wiki http://haskell.org/haskellwiki/Yhc/Javascript/Users_guide#Building_and_inst… which, among other things, requires cleaning up tabs for the formatting to work. Even if it can't be incorporated into the buildbot, it would be nice to have some working make examples to orient one's self. Secondly, with regards to your cps changes, are you aware of *any* demos that will compile from head? I want to get going with this because I have a situation where ycr2js would be really useful for an in-house project, client side table filtering on large tables. Maybe I should say a bit about this as well so you can tell me if this seems realistic, I'll write a separate email about that. t. > > Not all of them may be compilable at the moment though (and some will > never be compilable in the future, just kept there for historic > reasons - that's why they are not being tested by the buildbot). > > I am currently going through transition from plain CPS to Cont monad, > so regular monadic notation can be used instead of CPS. However I am > experiencing memory leaks in MSIE (try the EchoM example) which I did > not expect to happen (never had them in plain CPS). If I cannot fix > that I'll roll back to plain CPS. > > On 11/26/07, Thomas Hartman <tphyahoo(a)gmail.com> wrote: > > It would be really helpful if you could include this (and other) > > examples in an /examples directory under > > > > src/translator/js > > > -- > Dimitry Golubovsky > > Anywhere on the Web >

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Re: getDirectoryContents still causing problems Re: problems building ycr2js (hopefully fixed)
by Thomas Hartman 27 Nov '07

27 Nov '07

Based on my experience, I wouldn't recommend doing scons fullclean; rather, I would darcs checkout and go from scratch. Annoying, but seems to work better. thomas. 2007/11/26, Dimitry Golubovsky <golubovsky(a)gmail.com>: > Thomas, > > This happens sometimes as Yhc depends on many other packages not very > well in sync (e. g. FilePath). Plus, internal dependencies are not > always tracked very well. Or binary core format gets upgraded (that > means, the core linker does not accept older versions of core files, > and all of them have to be regenerated). > > You may see sometimes recommendations in the Yhc mailing list: pull > patches, then do scons fullclean. Or re-check the whole repo out, > which is basically the same. > > Thanks. > > On 11/26/07, Thomas Hartman <tphyahoo(a)gmail.com> wrote: > > False alarm. > > > > I rm -rf ed yhhc, fresh darcs got the latest yhc, reinstalled yhc, and redid > > > > (cd src/translator/js; make all install) > > > > and it built. > > > > 2007/11/26, Dimitry Golubovsky <golubovsky(a)gmail.com>: > > > Thomas, > > > > > > It looks like this comes from Yhc, not from the Javascript backend. > > > > > > Have you done the full sequence of (starting with clean repo)? > > > > > > darcs get darcs.haskell.org/yhc > > > scons core=1 build > > > scons prefix=... install # whatever your stuff goes, and yhc will be > > > in bin/ from that, and this bin/ should be on your path > > > (cd src/translator/js; make all install) > > > > > > Please let me know where it fails. > > > > > > Thank you. > > > > > > On 11/26/07, Thomas Hartman <tphyahoo(a)gmail.com> wrote: > > > > still having problems darcs pulling your updates, related to System.FilePath. > > > > > > > > did you make clean and then make again? > > > > > > > > I darcs pulled everything. > > > > > > > > (cd src/translator/js; make all install) > > > > > > > > ... ... > > > > (cd /home/thartman/haskell-installs/yhc-install/yhc/src/translator/js/lib/haskell; > > > > \ > > > > for f in `find . -name '*.hs' | sort` ; do make -s -f > > > > /home/thartman/haskell-installs/yhc-install/yhc/src/translat\ > > > > or/js/Makefile `dirname $f`/`basename $f .hs`.ycr ; done) > > > > yhc: /home/thartman/haskell-installs/yhc-install/yhc/inst/lib/yhc/packages: > > > > getDirectoryContents: does not exist (No such fi\ > > > > le or directory) > > > > > > > > -s flag silences, we don't want that, with verbose output again we see > > > > that make is failing for a huge number of packages > > > > > > > > (cd /home/thartman/haskell-installs/yhc-install/yhc/src/translator/js/lib/h\ > > > > askell; \ > > > > for f in `find . -name '*.hs' | sort` ; do make -f > > > > /home/thartman/haskell-installs/yhc-install/yhc/src/translator/\ > > > > js/Makefile `dirname $f`/`basename $f .hs`.ycr ; done) > > > > > yhc --core --no-bytecode CDOM/Level1/DomUtils.hs > > > > yhc: /home/thartman/haskell-installs/yhc-install/yhc/inst/lib/yhc/packages: > > > > getDirectoryContents: does not exist (No such fi\ > > > > le or directory) > > > > > > > > make: *** [CDOM/Level1/DomUtils.ycr] Error 1 > > > > yhc --core --no-bytecode CDOM/Level1/Events.hs > > > > yhc: /home/thartman/haskell-installs/yhc-install/yhc/inst/lib/yhc/packages: > > > > getDirectoryContents: does not exist (No such fi\ > > > > le or directory) > > > > > > > > ... > > > > > > > > thartman@none:~/haskell-installs/yhc-install/yhc/src/translator/js/lib/haskell>yhc > > > > --core --no-bytecode CDOM/Level1/DomUtils\ > > > > .hs > > > > yhc: /home/thartman/haskell-installs/yhc-install/yhc/inst/lib/yhc/packages: > > > > getDirectoryContents: does not exist (No such fi\ > > > > le or directory) > > > > > > > > Unfamiliar with yhc, I couldn't figure out where getDirectory contents > > > > is being called from. > > > > > > > > Grepping at the root, I guess something here is causing problems > > > > > > > > thartman@none:~/haskell-installs/yhc-install/yhc>grep -irl > > > > getDirectoryContents * > > > > Make/Useful.hs > > > > inst/bin/yhc > > > > src/compiler98/Package.hs > > > > src/packages/yhc-base-1.0/System/Directory.hs > > > > src/packages/haskell98-1.0/Directory.hs > > > > src/tester/Main.hs > > > > tests/conformance98/Directory/getDirContents/Main.hs > > > > > > > > best, thomas. > > > > > > > > 2007/11/25, Dimitry Golubovsky <golubovsky(a)gmail.com>: > > > > > Thomas, > > > > > > > > > > On Nov 25, 2007 5:50 PM, Thomas Hartman <tphyahoo(a)gmail.com> wrote: > > > > > > Thanks Dmitri, I also had to fix an issue with System.FilePath, > > > > > > there's a message about this on haskell cafe. > > > > > > > > > > In fact, takeDirectory is the right replacement for getDirectory in > > > > > older FilePath. I have pushed this change too. > > > > > > > > > > Thanks. > > > > > > > > > > -- > > > > > Dimitry Golubovsky > > > > > > > > > > Anywhere on the Web > > > > > > > > > > > > > > > > > > -- > > > Dimitry Golubovsky > > > > > > Anywhere on the Web > > > > > > > > -- > Dimitry Golubovsky > > Anywhere on the Web >

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Re: getDirectoryContents still causing problems Re: problems building ycr2js (hopefully fixed)
by Thomas Hartman 27 Nov '07

27 Nov '07

False alarm. I rm -rf ed yhhc, fresh darcs got the latest yhc, reinstalled yhc, and redid (cd src/translator/js; make all install) and it built. 2007/11/26, Dimitry Golubovsky <golubovsky(a)gmail.com>: > Thomas, > > It looks like this comes from Yhc, not from the Javascript backend. > > Have you done the full sequence of (starting with clean repo)? > > darcs get darcs.haskell.org/yhc > scons core=1 build > scons prefix=... install # whatever your stuff goes, and yhc will be > in bin/ from that, and this bin/ should be on your path > (cd src/translator/js; make all install) > > Please let me know where it fails. > > Thank you. > > On 11/26/07, Thomas Hartman <tphyahoo(a)gmail.com> wrote: > > still having problems darcs pulling your updates, related to System.FilePath. > > > > did you make clean and then make again? > > > > I darcs pulled everything. > > > > (cd src/translator/js; make all install) > > > > ... ... > > (cd /home/thartman/haskell-installs/yhc-install/yhc/src/translator/js/lib/haskell; > > \ > > for f in `find . -name '*.hs' | sort` ; do make -s -f > > /home/thartman/haskell-installs/yhc-install/yhc/src/translat\ > > or/js/Makefile `dirname $f`/`basename $f .hs`.ycr ; done) > > yhc: /home/thartman/haskell-installs/yhc-install/yhc/inst/lib/yhc/packages: > > getDirectoryContents: does not exist (No such fi\ > > le or directory) > > > > -s flag silences, we don't want that, with verbose output again we see > > that make is failing for a huge number of packages > > > > (cd /home/thartman/haskell-installs/yhc-install/yhc/src/translator/js/lib/h\ > > askell; \ > > for f in `find . -name '*.hs' | sort` ; do make -f > > /home/thartman/haskell-installs/yhc-install/yhc/src/translator/\ > > js/Makefile `dirname $f`/`basename $f .hs`.ycr ; done) > > > yhc --core --no-bytecode CDOM/Level1/DomUtils.hs > > yhc: /home/thartman/haskell-installs/yhc-install/yhc/inst/lib/yhc/packages: > > getDirectoryContents: does not exist (No such fi\ > > le or directory) > > > > make: *** [CDOM/Level1/DomUtils.ycr] Error 1 > > yhc --core --no-bytecode CDOM/Level1/Events.hs > > yhc: /home/thartman/haskell-installs/yhc-install/yhc/inst/lib/yhc/packages: > > getDirectoryContents: does not exist (No such fi\ > > le or directory) > > > > ... > > > > thartman@none:~/haskell-installs/yhc-install/yhc/src/translator/js/lib/haskell>yhc > > --core --no-bytecode CDOM/Level1/DomUtils\ > > .hs > > yhc: /home/thartman/haskell-installs/yhc-install/yhc/inst/lib/yhc/packages: > > getDirectoryContents: does not exist (No such fi\ > > le or directory) > > > > Unfamiliar with yhc, I couldn't figure out where getDirectory contents > > is being called from. > > > > Grepping at the root, I guess something here is causing problems > > > > thartman@none:~/haskell-installs/yhc-install/yhc>grep -irl > > getDirectoryContents * > > Make/Useful.hs > > inst/bin/yhc > > src/compiler98/Package.hs > > src/packages/yhc-base-1.0/System/Directory.hs > > src/packages/haskell98-1.0/Directory.hs > > src/tester/Main.hs > > tests/conformance98/Directory/getDirContents/Main.hs > > > > best, thomas. > > > > 2007/11/25, Dimitry Golubovsky <golubovsky(a)gmail.com>: > > > Thomas, > > > > > > On Nov 25, 2007 5:50 PM, Thomas Hartman <tphyahoo(a)gmail.com> wrote: > > > > Thanks Dmitri, I also had to fix an issue with System.FilePath, > > > > there's a message about this on haskell cafe. > > > > > > In fact, takeDirectory is the right replacement for getDirectory in > > > older FilePath. I have pushed this change too. > > > > > > Thanks. > > > > > > -- > > > Dimitry Golubovsky > > > > > > Anywhere on the Web > > > > > > > > -- > Dimitry Golubovsky > > Anywhere on the Web >

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getDirectoryContents still causing problems Re: problems building ycr2js (hopefully fixed)
by Thomas Hartman 27 Nov '07

27 Nov '07

still having problems darcs pulling your updates, related to System.FilePath. did you make clean and then make again? I darcs pulled everything. (cd src/translator/js; make all install) ... ... (cd /home/thartman/haskell-installs/yhc-install/yhc/src/translator/js/lib/haskell; \ for f in `find . -name '*.hs' | sort` ; do make -s -f /home/thartman/haskell-installs/yhc-install/yhc/src/translat\ or/js/Makefile `dirname $f`/`basename $f .hs`.ycr ; done) yhc: /home/thartman/haskell-installs/yhc-install/yhc/inst/lib/yhc/packages: getDirectoryContents: does not exist (No such fi\ le or directory) -s flag silences, we don't want that, with verbose output again we see that make is failing for a huge number of packages (cd /home/thartman/haskell-installs/yhc-install/yhc/src/translator/js/lib/h\ askell; \ for f in `find . -name '*.hs' | sort` ; do make -f /home/thartman/haskell-installs/yhc-install/yhc/src/translator/\ js/Makefile `dirname $f`/`basename $f .hs`.ycr ; done) > yhc --core --no-bytecode CDOM/Level1/DomUtils.hs yhc: /home/thartman/haskell-installs/yhc-install/yhc/inst/lib/yhc/packages: getDirectoryContents: does not exist (No such fi\ le or directory) make: *** [CDOM/Level1/DomUtils.ycr] Error 1 yhc --core --no-bytecode CDOM/Level1/Events.hs yhc: /home/thartman/haskell-installs/yhc-install/yhc/inst/lib/yhc/packages: getDirectoryContents: does not exist (No such fi\ le or directory) ... thartman@none:~/haskell-installs/yhc-install/yhc/src/translator/js/lib/haskell>yhc --core --no-bytecode CDOM/Level1/DomUtils\ .hs yhc: /home/thartman/haskell-installs/yhc-install/yhc/inst/lib/yhc/packages: getDirectoryContents: does not exist (No such fi\ le or directory) Unfamiliar with yhc, I couldn't figure out where getDirectory contents is being called from. Grepping at the root, I guess something here is causing problems thartman@none:~/haskell-installs/yhc-install/yhc>grep -irl getDirectoryContents * Make/Useful.hs inst/bin/yhc src/compiler98/Package.hs src/packages/yhc-base-1.0/System/Directory.hs src/packages/haskell98-1.0/Directory.hs src/tester/Main.hs tests/conformance98/Directory/getDirContents/Main.hs best, thomas. 2007/11/25, Dimitry Golubovsky <golubovsky(a)gmail.com>: > Thomas, > > On Nov 25, 2007 5:50 PM, Thomas Hartman <tphyahoo(a)gmail.com> wrote: > > Thanks Dmitri, I also had to fix an issue with System.FilePath, > > there's a message about this on haskell cafe. > > In fact, takeDirectory is the right replacement for getDirectory in > older FilePath. I have pushed this change too. > > Thanks. > > -- > Dimitry Golubovsky > > Anywhere on the Web >

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New demo/test program for Yhc Javascript backend
by Dimitry Golubovsky 27 Nov '07

27 Nov '07

Hi, For those of you who are interested in using Haskell in client-side web application programming: I have added a new demo/test program to this Wiki page ("Does it leak?"): http://haskell.org/haskellwiki/Yhc/Javascript This demo program shows some progress made since the first announcement of Yhc Javascript backend (Core to Javascript converter) was made about a year ago. Please test the demo for functionality and memory leaks in various browsers. Your feedback is appreciated. The demo program is self-contained (does not require any Haskell libraries beyond those included with Yhc). There is a darcs repo: http://www.golubovsky.org/repos/wsptest/ from which this demo program along with Makefile can be obtained if anybody wants to play with the code. Thanks. -- Dimitry Golubovsky Anywhere on the Web

3 3

The Monad.Reader - Call for Copy
by Wouter Swierstra 26 Nov '07

26 Nov '07

Call for Copy The Monad.Reader - Issue 10 I would like to welcome articles for the anniversary issue of The Monad.Reader. * The Monad.Reader * The Monad.Reader is an 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, including: 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 by e-mail (wss at cs.nott.ac.uk) to me before ** January 25, 2008 ** Articles should be written according to the guidelines available from http://www.haskell.org/haskellwiki/The_Monad.Reader 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 sort something out. Looking forward to your submission, Wouter This message has been checked for viruses but the contents of an attachment may still contain software viruses, which could damage your computer system: you are advised to perform your own checks. Email communications with the University of Nottingham may be monitored as permitted by UK legislation.

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SingHaskell, Nov 28 (Second Call)
by Tom Schrijvers 26 Nov '07

26 Nov '07

What is SingHaskell? Sing(apore)Haskell is a Haskell (and related languages) meeting in Singapore. The meeting is organized by Tom Schrijvers ( Tom.Schrijvers(a)cs.kuleuven.be ) and Martin Sulzmann ( sulzmann(a)comp.nus.edu.sg ) and will be hosted by the National University of Singapore. Date and location Sing(apore)Haskell takes place on Wed 28 Nov 2007 (right before APLAS'07 http://flint.cs.yale.edu/aplas2007/) The meeting will be held on the National University of Singapore campus at COM1-02-VC (2nd floor video conference room, School of Computing) Further location details: http://www.comp.nus.edu.sg/aboutsoc/getting_to_soc_at_com1.htm http://www.comp.nus.edu.sg/corpcomm/location/maps.htm#com1 http://www.comp.nus.edu.sg/corpcomm/location/COM1_L2.htm The meeting starts at 9:30am and should end around 2pmish (with a lunch-break, on your own, in between) Let Tom or Martin know if you are interested in coming. Either to attend the meeting or even give a talk. Programme 9:30-9:55 Welcome, Quick intro to Haskell, Martin Sulzmann 10:00-10:25 First Class Constraint Programming in Haskell, Tom Schrijvers 10:30-10:55 Implementing STM in Concurrent Haskell, Frank Huch 11:00-11:25 Rule-based concurrent programming in Haskell, Edmund Lam 11:30-11:55 XHaskell - Adding regular expression types to Haskell, Kenny 12:00 - 12:25 Static Contract Checking for Haskell, Dana Xu 12:30 - 13:20 Lunch break 13:30 - 13:25 Functional dependencies versus type functions and beyond, Martin Sulzmann 13:30-13:55 Bernd Brassel For more information, see http://taichi.ddns.comp.nus.edu.sg/taichiwiki/SingHaskell2007 -- Tom Schrijvers Department of Computer Science K.U. Leuven Celestijnenlaan 200A B-3001 Heverlee Belgium tel: +32 16 327544 e-mail: tom.schrijvers(a)cs.kuleuven.be url: http://www.cs.kuleuven.be/~toms/

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Re: problems building ycr2js (hopefully fixed)
by Dimitry Golubovsky 26 Nov '07

26 Nov '07

Thomas, On Nov 25, 2007 5:50 PM, Thomas Hartman <tphyahoo(a)gmail.com> wrote: > Thanks Dmitri, I also had to fix an issue with System.FilePath, > there's a message about this on haskell cafe. In fact, takeDirectory is the right replacement for getDirectory in older FilePath. I have pushed this change too. Thanks. -- Dimitry Golubovsky Anywhere on the Web

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problems building ycr2js (hopefully fixed)
by Dimitry Golubovsky 26 Nov '07

26 Nov '07

Hi, I have made the file `addtags.idl' part of the repo. Please do scons update and see if it compiles. PS If there are any other problems with Yhc/Javascript backend, please CC me, golubovsky(a)gmail.com Thanks -- Dimitry Golubovsky Anywhere on the Web

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problems building ycr2js
by Dimitry Golubovsky 26 Nov '07

26 Nov '07

Hi again, I'm thinking: if this all is about a small file, addtags.idl which is generated in some unusual way, I might just add it to the distributable source tree, and then nobody would have had problems with ${var:m:n} substitution. Thanks. -- Dimitry Golubovsky Anywhere on the Web

1 0

Re: [Haskell-cafe] Libraries need a new owner
by Don Stewart 26 Nov '07

26 Nov '07

bernardy: > On Nov 25, 2007 9:23 PM, Don Stewart <dons(a)galois.com> wrote: > > > > What are the long term goals of the project? To merge key data > > structures into the containers library? > > > > They are a more like a replacement, with (almost) the same api, and > better performance (last time we checked). > > Besides, I maintain a common class framework API to use (and test, etc.) > all those beasts uniformly. Can you give an overview of which data structures we now have better replacements for, and what is preventing them being replaced? Perhaps a good next step would be to break containers up into smaller pieces, so that individual parts of the containers library can be selectively replaced? Once we have experience with what breaks, and what is faster, then we can proceed to replace components? -- Don

1 0

problems building ycr2js
by Dimitry Golubovsky 26 Nov '07

26 Nov '07

Hi, This is my stuff, and I am of course willing to fix this to make more compatible. I am not really deep into this "shell hell" (that is, used anything that worked for me not seeing much difference between shells in e. g. Archlinux vs. Ubuntu), but if there are any suggestions what could be fixed (if at all) please let me know. Thanks. -- Dimitry Golubovsky Anywhere on the Web

1 0

Searched for mdo on haskell.org. Found nothing.
by Richard Kelsall 26 Nov '07

26 Nov '07

I was reading the 'Problems with do notation' thread and Thomas Schilling suggested reading about mdo. Not knowing mdo I thought that sounds interesting and went to http://haskell.org/ which redirects you to http://haskell.org/haskellwiki/Haskell and gives you a search box. Typing mdo and clicking the Search button gives "Showing below 0 results starting with #1. No page title matches No page text matches Note: unsuccessful searches are often caused by searching for common words like "have" and "from", which are not indexed, or by specifying more than one search term (only pages containing all of the search terms will appear in the result)." Maybe mdo is too common to be indexed? So I went to Google and searched for Haskell mdo and top of the list is this page : http://www.haskell.org/ghc/docs/latest/html/users_guide/syntax-extns.html which is Chapter 8. GHC Language Features 8.3. Syntactic extensions which describes mdo. Did I do something wrong when searching haskell.org? Richard.

6 8

Haskell code in Wordpress
by Paulo J. Matos 26 Nov '07

26 Nov '07

Hi all, I'm curious about the best way to typeset haskell code in a wordpress blog. Using blockquote removes all indentation. :-( Cheers, -- Paulo Jorge Matos - pocm at soton.ac.uk http://www.personal.soton.ac.uk/pocm PhD Student @ ECS University of Southampton, UK

6 6

problems building ycr2js
by Thomas Hartman 25 Nov '07

25 Nov '07

OK, I struggled through the instructions at http://haskell.org/haskellwiki/Yhc/Javascript/Users_guide#Downloading and am getting tripped up at (cd src/translator/js; make all install) any advice? ... blah blah blah.... ghc --make -i../../../depends/filepath splitter.hs -o /home/thartman/haskell-installs/yhc-install/yhc/src/translator/js/inst\ /bin/splitter [1 of 4] Compiling System.FilePath.Version_0_11 ( ../../../depends/filepath/System/FilePath/Version_0_11.hs, ../../../depend\ s/filepath/System/FilePath/Version_0_11.o ) [2 of 4] Compiling System.FilePath ( ../../../depends/filepath/System/FilePath.hs, ../../../depends/filepath/System/FilePat\ h.o ) [4 of 4] Compiling Main ( splitter.hs, splitter.o ) Linking /home/thartman/haskell-installs/yhc-install/yhc/src/translator/js/inst/bin/splitter ... echo > W3C/addtags.idl for tag in SUB SUP SPAN BDO I B U S \ STRIKE BIG SMALL EM STRONG DFN CODE \ SAMP KBD VAR CITE ACRONYM ABBR \ DD DT NOFRAMES NOSCRIPT ADDRESS CENTER ; do \ ltag=`echo ${tag:1} | tr [:upper:] [:lower:]` ; \ echo " interface HTML${tag:0:1}${ltag}Element : HTMLElement {" >> W3C/addtags.idl ; \ echo " };" >> W3C/addtags.idl ; \ echo >> W3C/addtags.idl ; \ done /bin/sh: Syntax error: Bad substitution make: *** [W3C/addtags.idl] Error 2

2 5

emacs haskellers: r-stripping files becomes popular
by Valery V. Vorotyntsev 25 Nov '07

25 Nov '07

Add the following lines to your ~/.emacs: ------- BEGIN OF ELISP CODE ------- ;(global-set-key (kbd "<f9> s") 'delete-trailing-whitespace) (defun delete-trailing-whitespace-if-confirmed () "Delete all the trailing whitespace across the current buffer, asking user for confirmation." (if (and (save-excursion (goto-char (point-min)) (re-search-forward "[[:space:]]$" nil t)) (y-or-n-p "Delete trailing whitespace? ")) (delete-trailing-whitespace))) (add-hook 'before-save-hook 'delete-trailing-whitespace-if-confirmed) ------- END OF ELISP CODE ------- Have fun! -- vvv

6 9

is there a more concise way to generate helper functions for a datatype built on records?
by Thomas Hartman 25 Nov '07

25 Nov '07

I think I'm running into more or less the same issue discussed at http://bloggablea.wordpress.com/2007/04/24/haskell-records-considered-grung… Just wondering if I missed anything, or if any of the ideas considering better records setter/getters have been implemented in the meantime. t. ************** -- Is there any way to do the following more concisely? -- Seems like a lot of boilerplate data GameState = GameState { guesses :: Int, userHighScores :: UserHighScores, answer :: Maybe Int } deriving Show -- State Helpers --------------------------------------- modGuesses f gSt = _set_guesses ( (f . guesses) gSt) gSt modUserHighScores f gSt = _set_userHighScores ( (f . userHighScores) gSt) gSt modAnswer f gSt = _set_answer ( (f . answer) gSt) gSt _set_guesses new gSt = gSt {guesses=new} _set_userHighScores new gSt = gSt { userHighScores=new } _set_answer new gSt = gSt { answer=new }

5 4

nhc vs ghc
by brad clawsie 25 Nov '07

25 Nov '07

can anyone provide a concise list of the major differences between nhc98 and ghc? for example, can i build a cabal package with nhc98? i get that ghc and nhc98 are not interchangeable, otherwise i am not sure thanks

7 7

been scouring through the Haskell prelude to no avail ...
by Galchin Vasili 25 Nov '07

25 Nov '07

Hello, Is there any predefined datatype that can be used to represent a two byte value? Kind regards, Vasili

2 1

Re: [Yhc] Re: [Haskell-cafe] yhc install fails
by Thomas Hartman 25 Nov '07

25 Nov '07

Thanks, that worked. I think there's some weird issue with the way the build happens that requires you to do rm -rf yhc; darccs get http://...yhc for a truly "fair" build to take place. I saw something in a bug report about how things get cached. That means that an ok from a buildbot doesn't mean that the build is really ok. It occurs to me that if it's possible to get the buildbot to do rm -rf and darcs re-checkout that might be worth doing, until the issues with stuff getting cached get resolved. But maybe that's smiting a mosquito with a flamethrower. thomas. 2007/11/22, Thomas Shackell <shackell(a)cs.york.ac.uk>: > Apologies, I broke this when I fixed the getArgs bug. It's actually just > a build problem, Storable needs to be built before C/String. I didn't > notice it because it only happens with a fresh (uncompiled) copy of yhc. > Anyway fix pushed. > > > Thanks > > Tom > > > > > Neil Mitchell wrote: > > Yhc people: > > > > On Nov 21, 2007 8:46 PM, Thomas Hartman <tphyahoo(a)gmail.com> wrote: > >> I'm having the devil of a time getting yhc to install. > >> > >> http://hpaste.org/4028 > >> > >> or for posterity > >> > >> root@none:~/yhc-install/yhc>scons > >> > >> ... blah blah blah... > >> > >> Compiling PreludeAux ( src/packages/yhc-base-1.0/PreludeAux.hs ) > >> YHC_build(["src/packages/yhc-base-1.0/Foreign/Util.hbc"], > >> ["src/packages/yhc-base-1.0/Foreign/Util.hs"]) > >> inst/bin/yhc --core --cpp -c src/packages/yhc-base-1.0/Foreign/Util.hs > >> Compiling Foreign.Util ( src/packages/yhc-base-1.0/Foreign/Util.hs ) > >> YHC_build(["src/packages/yhc-base-1.0/Foreign/C/String.hbc"], > >> ["src/packages/yhc-base-1.0/Foreign/C/String.hs"]) > >> inst/bin/yhc --core --cpp -c src/packages/yhc-base-1.0/Foreign/C/String.hs > >> Error: File not found, Foreign.Storable > >> Reason: imported from Foreign.C.String > >> Looked in: > >> /root/yhc-install/yhc/src/packages/yhc-base-1.0/ > >> /root/yhc-install/yhc/inst/lib/yhc/packages/yhc-base/1.0 > >> scons: *** [src/packages/yhc-base-1.0/Foreign/C/String.hbc] Error 1 > >> scons: building terminated because of errors. > >> > >> > >> root@none:~/yhc-install/yhc>ghc --version > >> The Glorious Glasgow Haskell Compilation System, version 6.8.1 > >> > >> advice? > >> > >> thomas. > >> _______________________________________________ > >> Haskell-Cafe mailing list > >> Haskell-Cafe(a)haskell.org > >> http://www.haskell.org/mailman/listinfo/haskell-cafe > >> > > _______________________________________________ > > Yhc mailing list > > Yhc(a)haskell.org > > http://www.haskell.org/mailman/listinfo/yhc > >

1 0

Call external program and get stdout
by Maurício 24 Nov '07

24 Nov '07

Hi, How can I call a program (like, for instance, 'grep text *') and get the standard output? All actions I found (executeFile, system) do not give me the output of the program. Thanks, Maurício

5 6

Unix (Posix) low-level device driver functionality?
by Galchin Vasili 24 Nov '07

24 Nov '07

Hello, I am seriously trying to push the mainstream computer industry. I am a kernel developer for POSIX OS's (e.g. Linux) and Windows. I would at the very least be able to write "test"/correctness software in Haskell where I am able to open Unix/Windows drivers and test storage firmware. The possibility exists in Houston to do this .. I want FPLs (in particular Haskell) to strut their "stuff" even on humble stubble stuff like firmware verification. In any case, it seems like the GHC documentation allows "raw driver I/O"but when I look at the actual GHC 6.8.1 libraries I don't see low level driver functionailty. Kind regards, Vasya

3 2

Composing monads
by Maurício 24 Nov '07

24 Nov '07

Hi, If I have two computations a->IO b and b->IO c, can I join them to get an a->IO c computation? I imagine something like a liftM dot operator. Thanks, Maurício

9 10

Polymorphic dynamic typing
by Paulo Silva 24 Nov '07

24 Nov '07

Hello, Type representations using GADTs are being used to achieve dynamic typing in Haskell. However, representing polymorphic types is problematic. Does anyone know any work about including polymorphism in dynamic typing? Best regards, Paulo

4 3