Re: [Haskell-cafe] ghc/dph
On 14/12/2010, at 13:35, Johannes Waldmann wrote: I want to use dph (data parallel haskell) for a presentation. (Nothing fancy, just compile and run some demos.) What ghc version should I use and where do I get it? That's a tricky question. We are currently working on getting DPH to work properly with GHC 7 but we aren't quite done yet. You might want to try 7.0.1 + the DPH sources from the darcs repo. I read the advice use HEAD but when I build from the 7.1.20101213 source snapshot, dph is not installed (should it be?) Nowadays, you have to install DPH separately which isn't easy since we haven't released the packages yet. In any case, DPH doesn't work with the current HEAD at all because I haven't adapted it to the new superclass story yet. Roman ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Functor = Applicative = Monad
3, John Smith volderm...@hotmail.com wrote: I would like to formally propose that Monad become a subclass of Applicative I'm not in favour of this change because of the code breakage issue. However, I think that an acceptable plan (mentioned elsewhere on the list, but doesn't seem to have had any subsequent discussion) would be to introduce a GHC warning for such cases: Warning: you are declaring a Monad instance for MyMonad without a corresponding Applicative instance. This will be an error in GHC 7.2 Then in 7.2 you can remove the warning and change the class hierarchy. (Substitute 7.4 for 7.2 if you think we need more time for library authors to update, or if you add the warning only to the 7.2 series). Cheers, Max ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Behaviour of System.Directory.getModificationTime
Hello, I am writing a program which scans a bunch of directories to detect changes (added, modified, deleted files). To detect modification, I would like to use getModification, doing something like the following: -- |Stores last modified timestamp of the file -- Yes, I come from Java... type HashMap = M.Map FilePath ClockTime data (Show a, Eq a) = Edit a = Mod a | Add a | Del a deriving (Eq,Show) checkChanges :: [String] - HashMap - IO ([Edit FilePath], HashMap) checkChanges [fs] m = do addedFilesList - lsRecursive fs timestamps - mapM getModificationTime addedFilesList let allts = zip addedFilesList timestamps let ret = (findDeletedFiles allts.updateScannedFiles allts) ([],m) return ret -- | Returns an updated map and a list of modified/added/deleted files updateScannedFiles :: [(FilePath,ClockTime)] - ([Edit FilePath], HashMap) - ([Edit FilePath], HashMap) updateScannedFiles []r = r updateScannedFiles ((path,ts):files) (updates,m) = case M.lookup path m of Nothing - updateScannedFiles files ((Add path:updates), M.insert path ts m) Just ts' - if ts' ts then updateScannedFiles files ((Mod path:updates), M.adjust (const ts) path m) else updateScannedFiles files (updates, m) -- omitting findDeletedFiles which is obvious and works I got the following test case that fails: recursively marks changed files as modified `for` do complexFileSetup -- create a small FS tree with 3 files root - tempDir state - checkChanges [root] M.empty writeFile (root / subdir / cFile.txt) this is another toast checkChanges [root] (snd state) = (\r - assertEqual there should be 1 changed file in 3 files 1 ((length.modified.fst) r)), In words: the getModificationTime of the overwritten file appears identical before and after the write. What am I doing wrong ? BTW, I checked the content of the file which has been correctly updated. Thanks for your help Arnaud ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [Haskell] Functor = Applicative = Monad
On 15/12/2010 04:01, Jonathan Geddes wrote: Fail can't just be removed. That would just break too much code. For example, I find myself writing code like the following: [a,b,c]- Just someList in place of let [a,b,c] = someList so that pattern match failure is lifted into the maybe monad (as long as I'm already in the maybe monad). I would like to see a MonadFail class, with one method 'fail', such that it is a compile-time error to try 'failable' pattern matches in a monad that is not an instance of MonadFail. --Jonathan Perhaps pattern match failures in a MonadPlus should bind to mzero - I believe that this is what your example and similar wish to achieve. I've updated http://haskell.org/haskellwiki/Functor-Applicative-Monad_Proposal to mention this. Does anyone know why fail and Pointed (in the paragraph This would eliminate...) aren't beginning a new paragraph? They are both preceded by a blank line in the wiki source. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] lhs2tex build failure
The latest version on GitHub should fix the problem. I'll make a new release soon. https://github.com/kosmikus/lhs2tex Cheers, Andres ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [Haskell] Functor = Applicative = Monad
Hi John,
John Smith wrote:
Perhaps pattern match failures in a MonadPlus should bind to mzero - I
believe that this is what your example and similar wish to achieve.
You updated the proposal to say:
a failed pattern match should error in the same way as is does for pure code,
while in
MonadPlus, the current behaviour could be maintained with mzero
Can you be more specific as to how that would interact with polymorphism
and type inference? What does it mean to be in MonadPlus? How does the
compiler know?
For example, what would be the static types and dynamic semantics of the
following expressions:
1. \a - do {Just x - return (Just a); return x}
2. do {Just x - return Nothing; return x}
3. \a - do {Just x - a; return x}
4. \a b - do {(x, _) - return (a, b); return x}
5. \a - do {(x, _) - return a; return x}
Tillmann
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Re: [Haskell-cafe] [Haskell] Functor = Applicative = Monad
Any refutable pattern match in do would force MonadFail (or MonadPlus if you
prefer). So
1. (MonadFail m) = a - m a, \ a - return a
2. (MonadFail m) = m a, mfail ...
3. (MonadFail m) = Maybe a - m a, \ a - case a of Nothing - mfail
...; Just x - return x
4. (Monad m) = a - b - m a, \ a b - return a
5. (Monad m) = (a, b) - m a, \ (a, b) - return a
As far as type inference and desugaring goes, it seems very little would
have to be changed in an implementation.
-- Lennart
2010/12/15 Tillmann Rendel ren...@informatik.uni-marburg.de
Hi John,
John Smith wrote:
Perhaps pattern match failures in a MonadPlus should bind to mzero - I
believe that this is what your example and similar wish to achieve.
You updated the proposal to say:
a failed pattern match should error in the same way as is does for pure
code, while in
MonadPlus, the current behaviour could be maintained with mzero
Can you be more specific as to how that would interact with polymorphism
and type inference? What does it mean to be in MonadPlus? How does the
compiler know?
For example, what would be the static types and dynamic semantics of the
following expressions:
1. \a - do {Just x - return (Just a); return x}
2. do {Just x - return Nothing; return x}
3. \a - do {Just x - a; return x}
4. \a b - do {(x, _) - return (a, b); return x}
5. \a - do {(x, _) - return a; return x}
Tillmann
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Re: [Haskell-cafe] [Haskell] Functor = Applicative = Monad
John Smith proposed: a failed pattern match should error in the same way as is does for pure code, while in MonadPlus, the current behaviour could be maintained with mzero Lennart Augustsson wrote: Any refutable pattern match in do would force MonadFail (or MonadPlus if you prefer). I guess that would work out, but I think John proposed something else. Tillmann ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ghc/dph
It looks like your best bet may be to use GHC 6.12 but then the question remains: what version exactly, and where do I get it. it seems I need something that was HEAD at the time (6.13.* ?) but I don't find older snapshot releases on http://haskell.org/ghc/dist/ Thanks - J.W. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] par / pseq example
I was trying to find an easy example for par/pseq, and I finally used plain mergesort ( on Prelude.[] ) and I observed that it is best to give +RTS -A1G (or more) such that there are only very few garbage collections. This roughly cuts execution time in half (from +RTS -N1 to -N4, on an i7 CPU) which is nice for a demonstration. The following is the very straightforward program that I use. Is it OK? I'm not asking for a faster sort algorithm, but whether par/pseq is used correctly/idiomatically in this program (so that students don't get a wrong impression). msort [] = [] ; msort [x] = [x] msort xs = let ( here, there ) = splitAt ( div ( length xs ) 2 ) xs mshere = msort here msthere = msort there inlast mshere `par` last msthere `pseq` merge mshere msthere merge [] ys = ys ; merge xs [] = xs merge (x:xs) (y:ys) = if x y then x : merge xs (y:ys) else y : merge (x:xs) ys Thanks - J.W. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] TLS package server interface do not seem to allow for asyncrhonious communication
On Wed, Dec 15, 2010 at 12:20 AM, Antoine Latter aslat...@gmail.com wrote: Maybe I'm missing something - but shouldn't the code listening on the Handle already be in it's own thread? The general recipe is: 1. Bind a socket to port 2. Call Network.accept, then take the resultant Handle, call forkIO with the TLS actions and the resultant handle. Go back to 1. Yes, for 99% of users this is the right thing to do. Note that Haskell threads are lightweight green threads and that under the hood you are getting efficient async networking using epoll() or kqueue() on Linux/OSX. G -- Gregory Collins g...@gregorycollins.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] installing gtk2
Hi everybody,I've got problems installing gtk2 onMac OS X 10.6.5.Here's the error message I receive when I try to install gtk2: bli-dor-nb01:~ max-buchholz$ sudo port install gvfs Password: --- Computing dependencies for gvfs --- Building gvfs Error: Target org.macports.build returned: shell command failed (see log for details) Log for gvfs is at: /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_release_ports_devel_gvfs/main.log Error: Status 1 encountered during processing. To report a bug, see http://guide.macports.org/#project.tickets bli-dor-nb01:~ max-buchholz$ sudo port install gtk2hs --- Computing dependencies for gtk2hs --- Dependencies to be installed: gvfs --- Building gvfs Error: Target org.macports.build returned: shell command failed (see log for details) Error: Failed to install gvfs Log for gvfs is at: /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_release_ports_devel_gvfs/main.log Error: The following dependencies were not installed: gvfs Error: Status 1 encountered during processing. To report a bug, see http://guide.macports.org/#project.tickets bli-dor-nb01:~ max-buchholzmce_markernbsp; bli-dor-nb01:~ max-buchholz$ sudo port install gtk2hs--- Computing dependencies for gtk2hs--- Dependencies to be installed: gvfs--- Building gvfsError: Target org.macports.build returned: shell command failed (see log for details)Error: Failed to install gvfsLog for gvfs is at: /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_release_ports_devel_gvfs/main.logError: The following dependencies were not installed: gvfsError: Status 1 encountered during processing.To report a bug, see http://guide.macports.org/#project.ticketsbli-dor-nb01:~ max-buchholzmce_markernbsp;Now I tried to install gvfs and receive the following:bli-dor-nb01:~ max-buchholz$ sudo port install gvfsPassword:--- Computing dependencies for gvfs--- Building gvfsError: Target org.macports.build returned: shell command failed (see log for details)Log for gvfs is at: /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_release_ports_devel_gvfs/main.logError: Status 1 encountered during processing.To report a bug, see http://guide.macports.org/#project.ticketsI hope you could help me!RegardsMax GRATIS! Movie-FLAT mit ber 300 Videos. Jetzt freischalten unter http://movieflat.web.de ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [Haskell] Functor = Applicative = Monad
On 15/12/2010 11:39, Lennart Augustsson wrote: Any refutable pattern match in do would force MonadFail (or MonadPlus if you prefer). So 1. (MonadFail m) = a - m a, \ a - return a 2. (MonadFail m) = m a, mfail ... 3. (MonadFail m) = Maybe a - m a, \ a - case a of Nothing - mfail ...; Just x - return x 4. (Monad m) = a - b - m a, \ a b - return a 5. (Monad m) = (a, b) - m a, \ (a, b) - return a As far as type inference and desugaring goes, it seems very little would have to be changed in an implementation. Is there a need for a MonadFail, as distinct from mzero? fail always seems to be defined as error in ordinary monads, and as mzero in MonadPlus (or left at the default error). ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [Haskell] Functor = Applicative = Monad
Yes, I think there should be a MonadFail distinct from MonadPlus. Some types, like IO, are not in MonadPlus, but have a special implementation of the fail method. Personally, I think fail should just be removed, but that would break existing code. The fail method was introduced for the wrong reasons (better error messages was the excuse). -- Lennart On Wed, Dec 15, 2010 at 11:51 AM, John Smith volderm...@hotmail.com wrote: On 15/12/2010 11:39, Lennart Augustsson wrote: Any refutable pattern match in do would force MonadFail (or MonadPlus if you prefer). So 1. (MonadFail m) = a - m a, \ a - return a 2. (MonadFail m) = m a, mfail ... 3. (MonadFail m) = Maybe a - m a, \ a - case a of Nothing - mfail ...; Just x - return x 4. (Monad m) = a - b - m a, \ a b - return a 5. (Monad m) = (a, b) - m a, \ (a, b) - return a As far as type inference and desugaring goes, it seems very little would have to be changed in an implementation. Is there a need for a MonadFail, as distinct from mzero? fail always seems to be defined as error in ordinary monads, and as mzero in MonadPlus (or left at the default error). ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GHC 7.0.1 developer challenges
On 13/12/2010 15:45, Peter Simons wrote: Hi Mathieu, Why don't you use ulimit for this job? $ ulimit -m 32M; ./cpsa yes, I was thinking the same thing. Relying exclusively on GHC's ability to limit run-time memory consumption feels like an odd choice for this task. It's nice that this feature exists in GHC, but it's inherently non-portable and outside of the scope of the language. There really ought to be a better way to catch an infinite loop that this. ulimit is a good way to catch an infinite loop. But it's not a good way to tell GHC how much memory you want to use - if GHC knows the memory limit, then it can make much more intelligent decisions about how to manage memory. The -M flag causes the GC algorithm to switch from copying (fast but hungry) to compaction (slow but frugal) as the limit approaches. Cheers, Simon ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Infinite lists in real world programs
Hello Café, I was wondering if using infinite lists was a viable and efficient solution in haskell programs (I mean not simple prototypes) : I was considering using them to model agents in a hierarchical multi-agent application for school. A list would representate the state of an agent at a step of the program. Let's say we have two simple agents, one multiplying its input by 2 and the other dividing it by 4 : agent1 = fmap (*2) agent2 = fmap (/4) allValues = xs where ys = agent1 xs xs = 100:agen2 ys main = do mapM_ print $ take 100 allValues Of course, in a real program, an agent would rather take a list of multiple agents (i.e. a list of lists) in input, so that its ouput could depend on what several agents feed him. Some could state what I'm trying to do is FRP, and I agree. But it remains a simple goal so I'd like to keep the program simple, and not go into the whole complexity of a FRP framework (and I'm working with a non-haskeller). For instance, with my solution, I cannot dynamically connect or disconnect agents during the runtime, but I'll will not need to do that in my program. Besides, I'd like to try to implement this myself, not use an already existing framework. So is it viable or would the use of multiple infinite lists kill the performances? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Rendering of hask in new wiki (MSIE6)
Hi, In MSIE6, hask tags are rendered like this (from the Monad_Transformers page): transformers: provides the classes MonadTrans and MonadIO , as well as concrete monad transformers such as StateT ... etc. The Wiki source: [http://hackage.haskell.org/package/transformers transformers]: provides the classes haskMonadTrans/hask and haskMonadIO/hask, as well as concrete monad transformers such as haskStateT/hask. HTML (a small piece of it): provides the classes div class=inline-codediv dir=ltr style=text-align: left;div class=source-haskell style=font-family: monospace;MonadTrans/div/div/div Words MonadTrans, MonadIO, StateT etc are enclosed in hask tags. They show up in monospace, each starting a new line. Is this only MSIE6, or this is how it is supposed to render? Thanks. PS I am not attaching a screenshot to the mailing list; if anyone needs to see it I'll send via personal e-mail. -- Dimitry Golubovsky Anywhere on the Web ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Rendering of hask in new wiki (MSIE6)
On Wed, Dec 15, 2010 at 09:01:49AM -0500, Dimitry Golubovsky wrote: HTML (a small piece of it): provides the classes div class=inline-codediv dir=ltr style=text-align: left;div class=source-haskell style=font-family: monospace;MonadTrans/div/div/div Words MonadTrans, MonadIO, StateT etc are enclosed in hask tags. They show up in monospace, each starting a new line. Is this only MSIE6, or this is how it is supposed to render? They're inline in FireFox. That text-align: seems unnecessary. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Iteratee-like
From: Permjacov Evgeniy permea...@gmail.com current links https://github.com/permeakra/Rank2Iteratee https://github.com/permeakra/PassiveIteratee The main difference from 'original' iteratees I read about is that both do not use 'chunks' and pass data one-by-one. So, what I wrote may be slower, but should be easier to maintain and more transparent for ghc optimising facilities. I wanted as clean and simple code as possible, but it is still very, very messy at some places and I want it cleaner. Any suggestions? I also want to check, how good ghc does its work with this messy modules. They may become interesting benchmarks. Have you tried comparing it to either iteratee or enumerator (which had mostly comparable performance last time I checked, with a slight edge to iteratee)? Or to Oleg's library? Try writing test cases, a simple byte-counting application, or similar, so you can compare the performance with the other versions. Both enumerator and iteratee include demo programs that you could use as a starting point. I agree that iteratees which work on a per-element level are very clean and should be amenable to optimization by GHC. It also shows a very clear relationship with stream-fusion techniques. Unfortunately when I last tried it I couldn't get acceptable performance. I was using ghc-6.12.1 IIRC, so it could be different now. John ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Rendering of hask in new wiki (MSIE6)
On Wed, 15 Dec 2010 15:01:49 +0100, Dimitry Golubovsky golubov...@gmail.com wrote: Hi, In MSIE6, hask tags are rendered like this (from the Monad_Transformers page): transformers: provides the classes MonadTrans and MonadIO , as well as concrete monad transformers such as StateT MSIE8 (with compatibility updates) and Opera on my system display the page correctly. Regards, Henk-Jan van Tuyl -- http://Van.Tuyl.eu/ http://members.chello.nl/hjgtuyl/tourdemonad.html -- ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GHC 7.0.1 developer challenges
Hi John, I think the previous responder was asserting the 32M limit, not you. I believe the previous poster suggested that you use ulimit to provide a hard upper bound for run-time memory use. That 32M figure seemed to be made up out of thin air just as an example to illustrate the syntax of the ulimit command. I don't have the impression that it was meant be any significant. [My program allows] users to set a step count bound, after which the program aborts. But guess what users do. They keep increasing the step count bound to see if just a few more steps will allow termination on their problem. Of course, some end up setting the bound so high, that thrashing occurs. I see. I must have misunderstood the situation. From your original posting, I got the impression that the program would depend on an externally enforced memory limit just to terminate at all! So for implementations of undecidable algorithms, you really need an intelligent memory bound on the GHC runtime. Well, some sort of externally enforced memory limit is useful, yes, but you don't strictly need that functionality in GHC. You can just as well use the operating system to enforce that limit, i.e. by means of 'ulimit'. Take care, Peter ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Infinite lists in real world programs
On Wed, Dec 15, 2010 at 02:52:11PM +0100, Yves Parès wrote: Hello Café, So is it viable or would the use of multiple infinite lists kill the performances? Sounds perfectly reasonable to me. I don't see any reason why using multiple infinite lists would have anything to do with the performance of your program -- unless you do something silly like try to compute their length. =) -Brent ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [Haskell] Functor = Applicative = Monad
On Wed, 2010-12-15 at 13:51 +0200, John Smith wrote: On 15/12/2010 11:39, Lennart Augustsson wrote: Any refutable pattern match in do would force MonadFail (or MonadPlus if you prefer). So 1. (MonadFail m) = a - m a, \ a - return a 2. (MonadFail m) = m a, mfail ... 3. (MonadFail m) = Maybe a - m a, \ a - case a of Nothing - mfail ...; Just x - return x 4. (Monad m) = a - b - m a, \ a b - return a 5. (Monad m) = (a, b) - m a, \ (a, b) - return a As far as type inference and desugaring goes, it seems very little would have to be changed in an implementation. Is there a need for a MonadFail, as distinct from mzero? fail always seems to be defined as error in ordinary monads, and as mzero in MonadPlus (or left at the default error). Not all types can implement mplus to begin with even if they can have 'zero' type. For example technically Maybe breaks the laws while still having useful fail: (guard . even) = (Just 1 | Just 2) (guard . even) = Just 1 guard (even 1) guard False Nothing /= Just () Nothing | Just () guard False | guard True (guard (even 1)) | (guard (even 2)) ((guard . even) = Just 1) | ((guard . even) = Just 2) Regards signature.asc Description: This is a digitally signed message part ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Infinite lists in real world programs
try to compute their length Yes ^^, that's silly. I don't see any reason why using multiple infinite lists would have anything to do with the performance That's comforting. Well, it seems to be a very simple, haskellish and elegant solution, so basic pragmatism -- with an slice of pessimism -- tells it was too good too be true ^^. 2010/12/15 Brent Yorgey byor...@seas.upenn.edu On Wed, Dec 15, 2010 at 02:52:11PM +0100, Yves Parès wrote: Hello Café, So is it viable or would the use of multiple infinite lists kill the performances? Sounds perfectly reasonable to me. I don't see any reason why using multiple infinite lists would have anything to do with the performance of your program -- unless you do something silly like try to compute their length. =) -Brent ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Rendering of hask in new wiki (MSIE6)
On Wed, 2010-12-15 at 09:01 -0500, Dimitry Golubovsky wrote: Hi, In MSIE6, hask tags are rendered like this (from the Monad_Transformers page): transformers: provides the classes MonadTrans and MonadIO , as well as concrete monad transformers such as StateT ... etc. The Wiki source: [http://hackage.haskell.org/package/transformers transformers]: provides the classes haskMonadTrans/hask and haskMonadIO/hask, as well as concrete monad transformers such as haskStateT/hask. HTML (a small piece of it): provides the classes div class=inline-codediv dir=ltr style=text-align: left;div class=source-haskell style=font-family: monospace;MonadTrans/div/div/div Words MonadTrans, MonadIO, StateT etc are enclosed in hask tags. They show up in monospace, each starting a new line. Is this only MSIE6, or this is how it is supposed to render? Thanks. PS I am not attaching a screenshot to the mailing list; if anyone needs to see it I'll send via personal e-mail. In epiphany (webkit) it displays OK. You can always test on pages like http://browsershots.org/http://haskell.org/haskellwiki/Monad_Transformers In general I'd say that MSIE should be avoided and updated to newer version like 7 or 8 (according to wikipedia they should be avaible for Windows XP - or at least they were available when Windows XP was supported) - IE6 have technology from 2001. I understand however that it may be outside your control (maybe portable Fx would be solution?) Regards PS. BTW - does anyone have statistics on browser share on Haskell site? According to Wikipedia IE6 have still around 16% market share but I guess it is lower here. signature.asc Description: This is a digitally signed message part ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [Haskell] Functor = Applicative = Monad
On Wed, Dec 15, 2010 at 06:25:30PM +0100, Maciej Piechotka wrote: On Wed, 2010-12-15 at 13:51 +0200, John Smith wrote: On 15/12/2010 11:39, Lennart Augustsson wrote: Any refutable pattern match in do would force MonadFail (or MonadPlus if you prefer). So 1. (MonadFail m) = a - m a, \ a - return a 2. (MonadFail m) = m a, mfail ... 3. (MonadFail m) = Maybe a - m a, \ a - case a of Nothing - mfail ...; Just x - return x 4. (Monad m) = a - b - m a, \ a b - return a 5. (Monad m) = (a, b) - m a, \ (a, b) - return a As far as type inference and desugaring goes, it seems very little would have to be changed in an implementation. Is there a need for a MonadFail, as distinct from mzero? fail always seems to be defined as error in ordinary monads, and as mzero in MonadPlus (or left at the default error). Not all types can implement mplus to begin with even if they can have 'zero' type. For example technically Maybe breaks the laws while still having useful fail: (guard . even) = (Just 1 | Just 2) (guard . even) = Just 1 guard (even 1) guard False Nothing /= Just () Nothing | Just () guard False | guard True (guard (even 1)) | (guard (even 2)) ((guard . even) = Just 1) | ((guard . even) = Just 2) But that depends on what laws you choose for MonadPlus. See http://www.haskell.org/haskellwiki/MonadPlus . -Brent ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Rendering of hask in new wiki (MSIE6)
Hi In general I'd say that MSIE should be avoided and updated to newer version like 7 or 8 (according to wikipedia they should be avaible for Windows XP - or at least they were available when Windows XP was supported) - IE6 have technology from 2001. I understand however that it may be outside your control (maybe portable Fx would be solution?) I strongly agree that MSIE 6 should be avoided, but for many company networks it's required. The big problem isn't that 16% (or whatever) of people use it, it's that while technical people will use a modern and powerful browser, many non-technical managers will just use the default settings/systems, and it gives a bad impression if when told that Haskell is a great tool a manager looks up haskell.org and sees a messy splat. For reference, the new Haddock style also gives various rendering issues in IE6. I reported these a while back (to Mark) but never got any response. Thanks, Neil ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [Haskell] Functor = Applicative = Monad
On 15 Dec 2010, at 17:48, Brent Yorgey wrote: On Wed, Dec 15, 2010 at 06:25:30PM +0100, Maciej Piechotka wrote: On Wed, 2010-12-15 at 13:51 +0200, John Smith wrote: On 15/12/2010 11:39, Lennart Augustsson wrote: Any refutable pattern match in do would force MonadFail (or MonadPlus if you prefer). So [..] As far as type inference and desugaring goes, it seems very little would have to be changed in an implementation. Is there a need for a MonadFail, as distinct from mzero? fail always seems to be defined as error in ordinary monads, and as mzero in MonadPlus (or left at the default error). Not all types can implement mplus to begin with even if they can have 'zero' type. For example technically Maybe breaks the laws while still having useful fail: [..] But that depends on what laws you choose for MonadPlus. See http://www.haskell.org/haskellwiki/MonadPlus . What has any of this to do with monads? Cheers Conor ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Iteratee-like
On 12/15/2010 05:48 PM, John Lato wrote: From: Permjacov Evgeniy permea...@gmail.com mailto:permea...@gmail.com current links https://github.com/permeakra/Rank2Iteratee https://github.com/permeakra/PassiveIteratee The main difference from 'original' iteratees I read about is that both do not use 'chunks' and pass data one-by-one. So, what I wrote may be slower, but should be easier to maintain and more transparent for ghc optimising facilities. I wanted as clean and simple code as possible, but it is still very, very messy at some places and I want it cleaner. Any suggestions? I also want to check, how good ghc does its work with this messy modules. They may become interesting benchmarks. Have you tried comparing it to either iteratee or enumerator (which had mostly comparable performance last time I checked, with a slight edge to iteratee)? Or to Oleg's library? Try writing test cases, a simple byte-counting application, or similar, so you can compare the performance with the other versions. Both enumerator and iteratee include demo programs that you could use as a starting point. I wrote a simple counter (attached,works for both variants of package), that literally counts bytes of given value in input. I got three-time slower result then with lazy io ( 0_o) with rank2types variant and six-seven time slower result with no CPS-version. Looks like ghc is really good with list fusion... I'm still reading tutorial from iteratee package, so I have not compared with it yet. An equivalend lazy io programm attached. Can someone give an advice how to improve performance? I agree that iteratees which work on a per-element level are very clean and should be amenable to optimization by GHC. It also shows a very clear relationship with stream-fusion techniques. Unfortunately when I last tried it I couldn't get acceptable performance. I was using ghc-6.12.1 IIRC, so it could be different now. John module Main where import Data.List import System.IO import System.Environment main = do (fn:ls:_) - getArgs flip mapM_ ls $ \ec - do fc - readFile fn let v = foldl' (\n cc - if ec == cc then (n+1) else n ) 0 fc putStrLn $ for character ++ show ec ++ count is ++ show v putStrLn $ all done module Main where import Data.Char import Data.Iteration.Types import Data.Iteration.IO.File import Data.Word import System.Environment main = do fn:cl:_ - getArgs flip mapM_ cl $ \c - do let ccc n = do cb - nextI (putStrLn $ count for char ++ show c ++ is ++ show n) (putStrLn . show) n `seq` if (cb == fromIntegral ( ord c ) ) then ccc (n + 1) else ccc n flip runIterator (fileE fn) $ mkI $ ccc 0 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Infinite lists in real world programs
It sounds like a good fit for your problem as stated. One thing to note is that Haskell will give you great abstractions for very strong amounts of code, as long as what you want to do is a good fit for the abstraction. Haskell makes it quite hard to fit a square peg into a round hole, so if one day you decide you need an agent that generates random numbers, you can either do dangerous stuff with unsafeInterleaveIO or you'll need to find a more flexible abstraction. Cheers, Edward ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Rendering of hask in new wiki (MSIE6)
On Wed, 2010-12-15 at 17:56 +, Neil Mitchell wrote: Hi In general I'd say that MSIE should be avoided and updated to newer version like 7 or 8 (according to wikipedia they should be avaible for Windows XP - or at least they were available when Windows XP was supported) - IE6 have technology from 2001. I understand however that it may be outside your control (maybe portable Fx would be solution?) I strongly agree that MSIE 6 should be avoided, but for many company networks it's required. The big problem isn't that 16% (or whatever) of people use it, it's that while technical people will use a modern and powerful browser, many non-technical managers will just use the default settings/systems, and it gives a bad impression if when told that Haskell is a great tool a manager looks up haskell.org and sees a messy splat. For reference, the new Haddock style also gives various rendering issues in IE6. I reported these a while back (to Mark) but never got any response. Thanks, Neil I cannot speak for anyone but from what I remember supporting MSIE is neither trivial nor fan. If you happen to use newer version of IE or even different operating system (if I remember correctly most of Haskell users use GNU/Linux) then you have bad luck - you have to use other tools like virtual machines etc. - only to find out that you have not been visited once by IE 6. I'm not sure how many changes are going to be commited into haddock backend/themes but once ported it would need to be maintained. Regards signature.asc Description: This is a digitally signed message part ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Infinite lists in real world programs
if one day you decide you need an agent that generates random numbers I could say that my agents now run in a certain monad, I just would have to transform my basic agents to : agent1 = liftM . fmap (*2) (or even agen1 = fmap . fmap (*2), however it is less readable IMO) Thanks for your comments. 2010/12/15 Edward Z. Yang ezy...@mit.edu It sounds like a good fit for your problem as stated. One thing to note is that Haskell will give you great abstractions for very strong amounts of code, as long as what you want to do is a good fit for the abstraction. Haskell makes it quite hard to fit a square peg into a round hole, so if one day you decide you need an agent that generates random numbers, you can either do dangerous stuff with unsafeInterleaveIO or you'll need to find a more flexible abstraction. Cheers, Edward ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Infinite lists in real world programs
On Wed, Dec 15, 2010 at 06:38:04PM +0100, Yves Parès wrote: try to compute their length Yes ^^, that's silly. I don't see any reason why using multiple infinite lists would have anything to do with the performance That's comforting. Well, it seems to be a very simple, haskellish and elegant solution, so basic pragmatism -- with an slice of pessimism -- tells it was too good too be true ^^. Premature pessimism is the root of all procrastination. -Brent ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Rendering of hask in new wiki (MSIE6)
On 15 December 2010 18:23, Maciej Piechotka uzytkown...@gmail.com wrote: For reference, the new Haddock style also gives various rendering issues in IE6. I reported these a while back (to Mark) but never got any response. Thanks, Neil I cannot speak for anyone but from what I remember supporting MSIE is neither trivial nor fan. If you happen to use newer version of IE or even different operating system (if I remember correctly most of Haskell users use GNU/Linux) then you have bad luck - you have to use other tools like virtual machines etc. - only to find out that you have not been visited once by IE 6. And you have to pay for a copy of MS-Windows to run in your VM. I.e. YOU (read I) have to pay to support someone else's broken software. So you wouldn't catch me trying to support IE 6 (or anything else). Standards have a good reason for existing. -- Colin Adams Preston, Lancashire, ENGLAND () ascii ribbon campaign - against html e-mail /\ www.asciiribbon.org - against proprietary attachments ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Infinite lists in real world programs
Excerpts from Yves Parès's message of Wed Dec 15 13:28:11 -0500 2010: if one day you decide you need an agent that generates random numbers I could say that my agents now run in a certain monad, I just would have to transform my basic agents to : agent1 = liftM . fmap (*2) (or even agen1 = fmap . fmap (*2), however it is less readable IMO) Yes, it's one of the really great things about Haskell. :-) But since implementing functionality takes so much less code in Haskell than in many other languages, don't be shy to rewrite as necessary. Edward ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Rendering of hask in new wiki (MSIE6)
On Wed, 15 Dec 2010 18:45:10 +0100, Maciej Piechotka uzytkown...@gmail.com wrote: : You can always test on pages like http://browsershots.org/http://haskell.org/haskellwiki/Monad_Transformers : : PS. BTW - does anyone have statistics on browser share on Haskell site? According to Wikipedia IE6 have still around 16% market share but I guess it is lower here. Statistics from A tour of the Haskell Monad functions (on my site), after 15.351 pageviews: Top 15 Browsers Browsers % Mozilla 1.975,07% Firesomething Add-On 12,06% Opera 9.6 3,46% Internet Explorer 8.0 2,96% Internet Explorer 7.0 1,73% Mozilla 1.81,61% Internet Explorer 6.0 1,31% Firefox 3.00,43% General Crawlers 0,39% Firefox 2.00,23% Konqueror 4.2 0,17% Opera 9.0 0,13% Opera 9.5 0,07% Opera 9.2 0,05% Konqueror 3.0 0,05% Top 10 operating systems Operating System % Linux 53,29% Windows XP 24,63% Windows Vista 9,17% Macintosh OS X 8,01% Windows 7 2,97% Windows 2003 0,67% FreeBSD0,56% SunOS 0,33% Windows 2000 0,29% Windows 98 0,04% Regards, Henk-Jan van Tuyl -- http://Van.Tuyl.eu/ http://members.chello.nl/hjgtuyl/tourdemonad.html -- ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Rendering of hask in new wiki (MSIE6)
Yes, the current syntax highligthing plugin (SyntaxHighlight_GeSHi) is quite annoying. It's the version that comes with debian which has the advantage that it will be updated automatically. However, it the surrounding div class=inline-code is my attempt at hacking around the fact that it doesn't even support inline-markup. Another issue is the weird way of trimming white space only on the first line. I'm now leaning towards writing a new custom plugin, but that means i have to write (and test) PHP code. Maybe I find some time over the holidays. If anyone else wants to propose another plugin, let me know. On 15 December 2010 14:01, Dimitry Golubovsky golubov...@gmail.com wrote: Hi, In MSIE6, hask tags are rendered like this (from the Monad_Transformers page): transformers: provides the classes MonadTrans and MonadIO , as well as concrete monad transformers such as StateT ... etc. The Wiki source: [http://hackage.haskell.org/package/transformers transformers]: provides the classes haskMonadTrans/hask and haskMonadIO/hask, as well as concrete monad transformers such as haskStateT/hask. HTML (a small piece of it): provides the classes div class=inline-codediv dir=ltr style=text-align: left;div class=source-haskell style=font-family: monospace;MonadTrans/div/div/div Words MonadTrans, MonadIO, StateT etc are enclosed in hask tags. They show up in monospace, each starting a new line. Is this only MSIE6, or this is how it is supposed to render? Thanks. PS I am not attaching a screenshot to the mailing list; if anyone needs to see it I'll send via personal e-mail. -- Dimitry Golubovsky Anywhere on the Web ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- Push the envelope. Watch it bend. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Rendering of hask in new wiki (MSIE6)
On 16/12/2010, at 3:31 AM, Ross Paterson wrote: On Wed, Dec 15, 2010 at 09:01:49AM -0500, Dimitry Golubovsky wrote: HTML (a small piece of it): provides the classes div class=inline-codediv dir=ltr style=text-align: left;div class=source-haskell style=font-family: monospace;MonadTrans/div/div/div Words MonadTrans, MonadIO, StateT etc are enclosed in hask tags. They show up in monospace, each starting a new line. Is this only MSIE6, or this is how it is supposed to render? They're inline in FireFox. That text-align: seems unnecessary. One normally expects div elements to be *block-level*; that's what div is for. Inline stuff should use span, that's what span is for. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Iteratee-like
On 12/15/2010 05:48 PM, John Lato wrote: From: Permjacov Evgeniy permea...@gmail.com mailto:permea...@gmail.com current links https://github.com/permeakra/Rank2Iteratee https://github.com/permeakra/PassiveIteratee The main difference from 'original' iteratees I read about is that both do not use 'chunks' and pass data one-by-one. So, what I wrote may be slower, but should be easier to maintain and more transparent for ghc optimising facilities. I wanted as clean and simple code as possible, but it is still very, very messy at some places and I want it cleaner. Any suggestions? I also want to check, how good ghc does its work with this messy modules. They may become interesting benchmarks. Have you tried comparing it to either iteratee or enumerator (which had mostly comparable performance last time I checked, with a slight edge to iteratee)? Or to Oleg's library? Try writing test cases, a simple byte-counting application, or similar, so you can compare the performance with the other versions. Both enumerator and iteratee include demo programs that you could use as a starting point. Ok, I tested with ByteString chunks and got roughly the same performance (less then 5 % difference) as with Data.Iteratee (as expected, as it is not a monad a bottlenec when using chunks). However, with Word8' streams I slows down to point six times slower then lazy IO. this is still may be acceptable if IO actions has to be performed while making nontrivial list fusions, but in general it is fail. Well, ghc has another complicated case for compiler optimisation tests. CPS-style with rank2 types provides boost to performance, but when using chunks it is insignificant, so haskell-98 version of iteratees may be used with no worries. I agree that iteratees which work on a per-element level are very clean and should be amenable to optimization by GHC. It also shows a very clear relationship with stream-fusion techniques. Unfortunately when I last tried it I couldn't get acceptable performance. I was using ghc-6.12.1 IIRC, so it could be different now. John ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GHC 7.0.1 developer challenges
On Wed, Dec 15, 2010 at 7:59 AM, Simon Marlow marlo...@gmail.com wrote: The -M flag causes the GC algorithm to switch from copying (fast but hungry) to compaction (slow but frugal) as the limit approaches. Ah, so that's what it's doing. My measurements say that part of the code is working well. Of course, my conclusion is based on a tiny sample size. John ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Gtk 0.12.0, Windows 7, Haskell Platform 2010.2.0.0, build error
Hi all, I am having some issues building Gtk2Hs on Windows 7. It completes compiling the whole thing and then errors out with this message: Registering gtk-0.12.0... setup.exe: WARNING: cache is out of date: c:/Program Files/Haskell Platform/2010.2.0.0\lib\package.conf.d\package.cache use 'ghc-pkg recache' to fix. gtk-0.12.0: library-dirs: c:/devel/dist/win32/libpng-1.4.3-1/lib doesn't exist or isn't a directory (use --force to override) cabal.exe: Error: some packages failed to install: gtk-0.12.0 failed during the building phase. The exception was: ExitFailure 1 I'm not sure why it's looking at c:/devel/dist/win32/libpng-1.4.3-1/lib and I couldn't find any reference to this directory in the source tree. I tried to do a ghc-pkg recache but I get the follow permissions error: ghc-pkg.exe: c:/Program Files/Haskell Platform/2010.2.0.0\lib\package.conf.d\package.cache: you don't have permission to modify this file I changed this file to be world-writeable but with the same results. I get the same error if I try and cabal install gtk. Thanks for your help. -deech ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Cabal message problem.
Hi, I see this kind of information a lot when I using cabal to install package. Or sometimes same packages both exist in global and user space, which is a shadowed by message. How to resolve that? Thanks. Resolving dependencies... command line: cannot satisfy -package Cabal-1.10.0.0: Cabal-1.10.0.0-9ac678c7f1e4f8dd31bac0e19f600698 is unusable due to missing or recursive dependencies: process-1.0.1.4-24e3819e5c17aaf49bfec6a0ab739420 (use -v for more information) -- 竹密岂妨流水过 山高哪阻野云飞 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Cabal message problem.
On 16 December 2010 13:35, Magicloud Magiclouds magicloud.magiclo...@gmail.com wrote: Hi, I see this kind of information a lot when I using cabal to install package. Or sometimes same packages both exist in global and user space, which is a shadowed by message. How to resolve that? Thanks. Resolving dependencies... command line: cannot satisfy -package Cabal-1.10.0.0: Cabal-1.10.0.0-9ac678c7f1e4f8dd31bac0e19f600698 is unusable due to missing or recursive dependencies: process-1.0.1.4-24e3819e5c17aaf49bfec6a0ab739420 (use -v for more information) This means you built Cabal-1.10.0.0 against process-1.0.1.4, but have subsequently upgraded (or downgraded or uninstalled) process. As such, rebuild Cabal. ghc-pkg check will give you a list of all broken packages. -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Haskell Weekly News: Issue 162 - December 15, 2010
Welcome to issue 162 of the HWN, a newsletter covering developments in the [1]Haskell community in the week of December 05 - 11. Wouter Swierstra [2]sent a call for papers for the ICFP 2011 to be held in Tokyo, Japan between September 19 - 21. The announcement contains all relevant dates of importance Dmitry Astapov [3]announced the realease of haskell-mpi, a suite of Haskell bindings to the C MPI [Message Passing Interface] and convenience APIs on top of it. David Waern [4]annouced a new version of the venerable Haddock. This version is compatible with .haddock files produced by the version of Haddock that comes with GHC 7.0.1. Michael Snoyman [5]announced the first release of his library and executable packdeps. This is a library and executable containing the same functionality as the original packdeps website, namely letting you know when your version bounds exclude the use of the newest version of a library available. Michael also [6]announced the second major release of the mime-mail library. This is a package providing support for rendering multipart emails. Jasper Van der Jeugt [7]announced the 0.0.2.0 release of the digestive functors library. The library provides a general API to input consumption, and is an upgrade of formlets. So, what went on this week? Top Reddit Stories * Cartesian Closed Comic: Résumé Domain: ro-che.info, Score: 35, Comments: 1 On Reddit: http://www.reddit.com/r/haskell/comments/ekiao/cartesian_closed_comic_résumé/ Original: http://ro-che.info/ccc/11.html * GHC blog: An overhaul of stack management, and some performance improvements Domain: hackage.haskell.org, Score: 32, Comments: 2 On Reddit: http://www.reddit.com/r/haskell/comments/emabe/ghc_blog_an_overhaul_of_stack_management_and_some/ Original: http://hackage.haskell.org/trac/ghc/blog/stack-chunks * How do You use Emacs for Haskell Development? Domain: self.haskell, Score: 29, Comments: 10 On Reddit: http://www.reddit.com/r/haskell/comments/ehl99/how_do_you_use_emacs_for_haskell_development/ Original: /r/haskell/comments/ehl99/how_do_you_use_emacs_for_haskell_development/ * Library versus Framework: Yesod's Own World Domain: docs.yesodweb.com, Score: 26, Comments: 22 On Reddit: http://www.reddit.com/r/haskell/comments/ejgen/library_versus_framework_yesods_own_world/ Original: http://docs.yesodweb.com/blog/yesods-own-world/ * Visualizing Haskell types part II, Gin and monotonic : Inside T5 Domain: blog.ezyang.com, Score: 24, Comments: 2 On Reddit: http://www.reddit.com/r/haskell/comments/eiaef/visualizing_haskell_types_part_ii_gin_and/ Original: http://blog.ezyang.com/2010/12/gin-and-monotonic/ * Package of the day: parallel-io: combinators for sequencing IO actions onto a thread pool Domain: hackage.haskell.org, Score: 21, Comments: 15 On Reddit: http://www.reddit.com/r/haskell/comments/ehsqo/package_of_the_day_parallelio_combinators_for/ Original: http://hackage.haskell.org/package/parallel-io-0.2.2 * Package of the day: haskell-mpi: Control.Parallel.MPI for high performance parallel (cluster) computations in Haskell Domain: hackage.haskell.org, Score: 19, Comments: 5 On Reddit: http://www.reddit.com/r/haskell/comments/ej5av/package_of_the_day_haskellmpi_controlparallelmpi/ Original: http://hackage.haskell.org/package/haskell-mpi-1.0.0 * From Polymorphism To Polytypism Domain: zenzike.com, Score: 19, Comments: On Reddit: http://www.reddit.com/r/haskell/comments/ejleb/from_polymorphism_to_polytypism/ Original: http://zenzike.com/posts/2010-12-10-from-polymorphic-to-polytypic/ * Hussling Haskell types into Hasse diagrams : Inside T5 Domain: blog.ezyang.com, Score: 18, Comments: On Reddit: http://www.reddit.com/r/haskell/comments/eh2zw/hussling_haskell_types_into_hasse_diagrams_inside/ Original: http://blog.ezyang.com/2010/12/hussling-haskell-types-into-hasse-diagrams/ * Building a business with Haskell: Case Studies: Cryptol, HaLVM and Copilot Domain: corp.galois.com, Score: 17, Comments: 1 On Reddit: http://www.reddit.com/r/haskell/comments/ejmwq/building_a_business_with_haskell_case_studies/ Original: http://corp.galois.com/blog/2010/12/10/building-a-business-with-haskell-case-studies-cryptol-halvm-1.html Top StackOverflow Questions * What is the benefit of purely functional data structure? votes: 15, answers: 4 Read on SO: http://stackoverflow.com/questions/4399837/what-is-the-benefit-of-purely-functional-data-structure * Haskell: Equation Expander 1+(1+(1+(1+(…=∞ votes: 9, answers: 2 Read on SO: http://stackoverflow.com/questions/4404663/haskell-equation-expander- * Pure Functional Language: Haskell votes: 7, answers: 6 Read on SO:
Re: [Haskell-cafe] cannot install regex-posix using cabal ?
canot it be fixed ? - e^(π.i) + 1 = 0 -- View this message in context: http://haskell.1045720.n5.nabble.com/cannot-install-regex-posix-using-cabal-tp3301201p3307465.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Cabal message problem.
On Thu, Dec 16, 2010 at 10:55 AM, Ivan Lazar Miljenovic ivan.miljeno...@gmail.com wrote: On 16 December 2010 13:35, Magicloud Magiclouds magicloud.magiclo...@gmail.com wrote: Hi, I see this kind of information a lot when I using cabal to install package. Or sometimes same packages both exist in global and user space, which is a shadowed by message. How to resolve that? Thanks. Resolving dependencies... command line: cannot satisfy -package Cabal-1.10.0.0: Cabal-1.10.0.0-9ac678c7f1e4f8dd31bac0e19f600698 is unusable due to missing or recursive dependencies: process-1.0.1.4-24e3819e5c17aaf49bfec6a0ab739420 (use -v for more information) This means you built Cabal-1.10.0.0 against process-1.0.1.4, but have subsequently upgraded (or downgraded or uninstalled) process. As such, rebuild Cabal. ghc-pkg check will give you a list of all broken packages. -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com The annoying thing is, I did not upgrade Cabal. Cabal and process are now coming with ghc 7. But many cabal packages do not know about this, I am not sure if this is cabal's fault or the packages'. So when installing some packages by cabal, they install the same version of, for example, process again. Then other packages depend on Cabal will give out this error. -- 竹密岂妨流水过 山高哪阻野云飞 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Cabal message problem.
On Thu, Dec 16, 2010 at 2:24 PM, Magicloud Magiclouds magicloud.magiclo...@gmail.com wrote: On Thu, Dec 16, 2010 at 10:55 AM, Ivan Lazar Miljenovic ivan.miljeno...@gmail.com wrote: On 16 December 2010 13:35, Magicloud Magiclouds magicloud.magiclo...@gmail.com wrote: Hi, I see this kind of information a lot when I using cabal to install package. Or sometimes same packages both exist in global and user space, which is a shadowed by message. How to resolve that? Thanks. Resolving dependencies... command line: cannot satisfy -package Cabal-1.10.0.0: Cabal-1.10.0.0-9ac678c7f1e4f8dd31bac0e19f600698 is unusable due to missing or recursive dependencies: process-1.0.1.4-24e3819e5c17aaf49bfec6a0ab739420 (use -v for more information) This means you built Cabal-1.10.0.0 against process-1.0.1.4, but have subsequently upgraded (or downgraded or uninstalled) process. As such, rebuild Cabal. ghc-pkg check will give you a list of all broken packages. -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com The annoying thing is, I did not upgrade Cabal. Cabal and process are now coming with ghc 7. But many cabal packages do not know about this, I am not sure if this is cabal's fault or the packages'. So when installing some packages by cabal, they install the same version of, for example, process again. Then other packages depend on Cabal will give out this error. -- 竹密岂妨流水过 山高哪阻野云飞 And, sure, I could reinstall Cabal. Then things seem fine. But it is weird. I have to have the same packages installed at two places of the system. -- 竹密岂妨流水过 山高哪阻野云飞 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] $ do?
From: Roman Cheplyaka r...@ro-che.info Sent: Wed, December 15, 2010 1:36:55 AM * Jonathan Geddes geddes.jonat...@gmail.com [2010-12-14 19:59:14-0700] Quick question: Why do I need the $ in the following bits of code? main = withSocketsDo $ do --do something with sockets foo = fromMaybe 0 $ do --do something in the maybe monad I don't see (after admittedly only a minute or so thinking about it) where any grammar ambiguities would be if 'do' had an implicit $ in front of it: foo = fromMaybe 0 do --do something in maybe Though now that I've written it down, that is hard for me to visually parse at a glance. I'm still curious though. Hi Jonathan, it's not clear whether you ask how this implies from the standard or what the rationale of such syntax is. Regarding the former, there are two distinct syntactic categories in Haskell: lexp and aexp. aexp produces all the constructs that can be used as function arguments and does not include do expressions. lexp is more broad and produces do expressions as well. Next look at these productions to see the difference between function application and operator application (sections 3.3 and 3.4 of 2010 report): fexp→ [fexp] aexp infixexp → lexp qop infixexp Regarding the rationale, I'm not so sure and I'd like to hear an explanation from someone competent. But I assume it has something to do with the fact that if you supply a 'do' argument, you cannot supply any more arguments (because 'do' extends to the right as far as possible). Not that I'm convinced that it is a valid reason to prohibit such construct. Years ago, I built GHC with a modified grammar including do and lambdas as aexp. It seemed to work. There were certainly conflicts reported by Happy, but examples seemed to work nicely and I couldn't think of any actual ambiguity. Brandon ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Beginners help
According to map's definition, we know the 'fs' should be a list of function. so 'p' need a [a-b] as its parameter.And the result of 'p' should be a list of function which accepts [a] and return [b]. So the type of 'p' is [a-b] - [[a] - [b]] hope i make it clear. - e^(π.i) + 1 = 0 -- View this message in context: http://haskell.1045720.n5.nabble.com/Beginners-help-tp3306796p3307470.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Cabal message problem.
On 16 December 2010 17:26, Magicloud Magiclouds magicloud.magiclo...@gmail.com wrote: And, sure, I could reinstall Cabal. Then things seem fine. But it is weird. I have to have the same packages installed at two places of the system. What makes you say that? Does ghc-pkg list show it twice? -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Cabal message problem.
On Thu, Dec 16, 2010 at 2:59 PM, Ivan Lazar Miljenovic ivan.miljeno...@gmail.com wrote: On 16 December 2010 17:26, Magicloud Magiclouds magicloud.magiclo...@gmail.com wrote: And, sure, I could reinstall Cabal. Then things seem fine. But it is weird. I have to have the same packages installed at two places of the system. What makes you say that? Does ghc-pkg list show it twice? -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com Yep. For example, now I have message as this when installing darcs. command line: cannot satisfy -package Cabal-1.10.0.0: Cabal-1.10.0.0-9ac678c7f1e4f8dd31bac0e19f600698 is unusable due to missing or recursive dependencies: process-1.0.1.4-24e3819e5c17aaf49bfec6a0ab739420 (use -v for more information) The only way I know to get rid of this is to install Cabal-1.10.0.0 again. Then you could see that, it exists both global and user. $ ghc-pkg list /usr/local/lib/ghc-7.0.1/package.conf.d Cabal-1.10.0.0 array-0.3.0.2 base-4.3.0.0 bin-package-db-0.0.0.0 bytestring-0.9.1.8 containers-0.4.0.0 directory-1.1.0.0 extensible-exceptions-0.1.1.2 ffi-1.0 filepath-1.2.0.0 ghc-7.0.1 ghc-binary-0.5.0.2 ghc-prim-0.2.0.0 haskell2010-1.0.0.0 haskell98-1.1.0.0 hpc-0.5.0.6 integer-gmp-0.2.0.2 old-locale-1.0.0.2 old-time-1.0.0.6 pretty-1.0.1.2 process-1.0.1.4 random-1.0.0.3 rts-1.0 template-haskell-2.5.0.0 time-1.2.0.3 unix-2.4.1.0 /home/magicloud/.ghc/i386-linux-7.0.1/package.conf.d Cabal-1.10.0.0 HTTP-4000.0.10 binary-0.5.0.2 containers-0.3.0.0 dataenc-0.13.0.4 deepseq-1.1.0.2 directory-1.0.1.2 filepath-1.1.0.4 html-1.0.1.2 mmap-0.5.7 mtl-1.1.1.1 network-2.2.1.10 parsec-2.1.0.1 process-1.0.1.4 regex-base-0.93.2 regex-compat-0.93.1 regex-posix-0.94.4 tar-0.3.1.0 terminfo-0.3.1.3 text-0.11.0.1 utf8-string-0.3.6 zlib-0.5.2.0 -- 竹密岂妨流水过 山高哪阻野云飞 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Cabal message problem.
On 16 December 2010 18:30, Magicloud Magiclouds magicloud.magiclo...@gmail.com wrote: On Thu, Dec 16, 2010 at 2:59 PM, Ivan Lazar Miljenovic For example, now I have message as this when installing darcs. command line: cannot satisfy -package Cabal-1.10.0.0: Cabal-1.10.0.0-9ac678c7f1e4f8dd31bac0e19f600698 is unusable due to missing or recursive dependencies: process-1.0.1.4-24e3819e5c17aaf49bfec6a0ab739420 (use -v for more information) The only way I know to get rid of this is to install Cabal-1.10.0.0 again. Then you could see that, it exists both global and user. $ ghc-pkg list /usr/local/lib/ghc-7.0.1/package.conf.d Cabal-1.10.0.0 array-0.3.0.2 base-4.3.0.0 bin-package-db-0.0.0.0 bytestring-0.9.1.8 containers-0.4.0.0 directory-1.1.0.0 extensible-exceptions-0.1.1.2 ffi-1.0 filepath-1.2.0.0 ghc-7.0.1 ghc-binary-0.5.0.2 ghc-prim-0.2.0.0 haskell2010-1.0.0.0 haskell98-1.1.0.0 hpc-0.5.0.6 integer-gmp-0.2.0.2 old-locale-1.0.0.2 old-time-1.0.0.6 pretty-1.0.1.2 process-1.0.1.4 random-1.0.0.3 rts-1.0 template-haskell-2.5.0.0 time-1.2.0.3 unix-2.4.1.0 /home/magicloud/.ghc/i386-linux-7.0.1/package.conf.d Cabal-1.10.0.0 HTTP-4000.0.10 binary-0.5.0.2 containers-0.3.0.0 dataenc-0.13.0.4 deepseq-1.1.0.2 directory-1.0.1.2 filepath-1.1.0.4 html-1.0.1.2 mmap-0.5.7 mtl-1.1.1.1 network-2.2.1.10 parsec-2.1.0.1 process-1.0.1.4 regex-base-0.93.2 regex-compat-0.93.1 regex-posix-0.94.4 tar-0.3.1.0 terminfo-0.3.1.3 text-0.11.0.1 utf8-string-0.3.6 zlib-0.5.2.0 You seem to have process installed twice... any reason for that? Possibly something has gone wrong with your user setup; try backing up your ~/.ghc, deleting it and try again. -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Cabal message problem.
On Thu, Dec 16, 2010 at 3:48 PM, Ivan Lazar Miljenovic ivan.miljeno...@gmail.com wrote: On 16 December 2010 18:30, Magicloud Magiclouds magicloud.magiclo...@gmail.com wrote: On Thu, Dec 16, 2010 at 2:59 PM, Ivan Lazar Miljenovic For example, now I have message as this when installing darcs. command line: cannot satisfy -package Cabal-1.10.0.0: Cabal-1.10.0.0-9ac678c7f1e4f8dd31bac0e19f600698 is unusable due to missing or recursive dependencies: process-1.0.1.4-24e3819e5c17aaf49bfec6a0ab739420 (use -v for more information) The only way I know to get rid of this is to install Cabal-1.10.0.0 again. Then you could see that, it exists both global and user. $ ghc-pkg list /usr/local/lib/ghc-7.0.1/package.conf.d Cabal-1.10.0.0 array-0.3.0.2 base-4.3.0.0 bin-package-db-0.0.0.0 bytestring-0.9.1.8 containers-0.4.0.0 directory-1.1.0.0 extensible-exceptions-0.1.1.2 ffi-1.0 filepath-1.2.0.0 ghc-7.0.1 ghc-binary-0.5.0.2 ghc-prim-0.2.0.0 haskell2010-1.0.0.0 haskell98-1.1.0.0 hpc-0.5.0.6 integer-gmp-0.2.0.2 old-locale-1.0.0.2 old-time-1.0.0.6 pretty-1.0.1.2 process-1.0.1.4 random-1.0.0.3 rts-1.0 template-haskell-2.5.0.0 time-1.2.0.3 unix-2.4.1.0 /home/magicloud/.ghc/i386-linux-7.0.1/package.conf.d Cabal-1.10.0.0 HTTP-4000.0.10 binary-0.5.0.2 containers-0.3.0.0 dataenc-0.13.0.4 deepseq-1.1.0.2 directory-1.0.1.2 filepath-1.1.0.4 html-1.0.1.2 mmap-0.5.7 mtl-1.1.1.1 network-2.2.1.10 parsec-2.1.0.1 process-1.0.1.4 regex-base-0.93.2 regex-compat-0.93.1 regex-posix-0.94.4 tar-0.3.1.0 terminfo-0.3.1.3 text-0.11.0.1 utf8-string-0.3.6 zlib-0.5.2.0 You seem to have process installed twice... any reason for that? Possibly something has gone wrong with your user setup; try backing up your ~/.ghc, deleting it and try again. -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com Yes. When I reinstalled Cabal to user space, it also installed process to user space again. And I also do not know why the global process does not fit it. But checking the package.conf.d shows: /usr/local/lib/ghc-7.0.1/package.conf.d/process-1.0.1.4-24e3819e5c17aaf49bfec6a0ab739420.conf /home/magicloud/.ghc/i386-linux-7.0.1/package.conf.d/process-1.0.1.4-dbac0acfd36adbff7779acc361040910.conf The hash code is different. Also are the Cabal-1.10.0.0-*.conf. Really hoping cabal has some kind of way to ignore these version thing. -- 竹密岂妨流水过 山高哪阻野云飞 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
