[Haskell-cafe] ANNOUNCE: text and text-icu, fast and comprehensive Unicode support using stream fusion
On behalf of the Data.Text team, I am delighted to announce the release of preview versions of two new packages: text 0.1 Fast, packed Unicode text support, using a modern stream fusion framework. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/text text-icu 0.1 Augments text with comprehensive character set conversion support and normalization (and soon more), via bindings to the ICU library. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/text-icu These packages fill out critical pieces of functionality for the Haskell platform, without compromising on either performance or safety. We are referring to these as *preview* releases because although the text package in particular has been quite heavily tested, it has not been thoroughly tuned, and we have not yet implemented a chunked lazy text representation suitable for streaming gigabytes of data. The APIs are pretty conventional, but are still subject to change. If you want to contribute, please get copies of the source trees from here: darcs get http://code.haskell.org/text darcs get http://darcs.serpentine.com/text-icu Please send bug reports and patches to your friendly Data.Text team: Tom Harper rthar...@aftereternity.co.uk Duncan Coutts duncan.cou...@worc.ox.ac.uk Bryan O'Sullivan b...@serpentine.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Status of Haskell under OsX
On 27 Feb 2009, at 08:17, Arne Dehli Halvorsen wrote: Manuel M T Chakravarty wrote: I'm planning to purchase a MacBookPro so I'm wondering how well Haskell is supported under this platform. At least two of the regular contributors to GHC work on Macs. That should ensure that Mac OS X is well supported. Installation is trivial with the Mac OS X installer package: http://haskell.org/ghc/download_ghc_6_10_1.html#macosxintel Good advice, but I've generally found the MacPorts version more consistantly built – plus, sudo port install ghc is nice and easy :) Hi, following on from this point: How does one get gtk2hs running on a mac? I have a MacBook Pro, and I've had ghc installed for some time now. (first in 6.8.2 (packaged), then 6.10.1 (packaged), then 6.8.2 via macports 1.6 then 6.10.1 via macports 1.7) I tried to install gtk2hs via macports, but it didn't work. (0.9.12? on 6.8.2, then on 6.10.1) Is there a recipe one could follow? Can I get the preconditions via macports, and then use cabal to install gtk2hs 0.10? For me, this worked: sudo port install ghc sudo port install gtk2 sudo port install cairomm curl http://downloads.sourceforge.net/gtk2hs/gtk2hs-0.10.0.tar.gz gtk2hs-0.10.0.tar.gz tar xvfz gtk2hs-0.10.0.tar.gz normal install stuff here. Bob___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: base-4 + gtk2hs-0.10.0 licensing
Am Donnerstag, 26. Februar 2009 21:39 schrieb Peter Hercek: The acceptable size of inlined fuctions for a C code is about 10 lines. I did not read any info how it would be for Haskell. At least, GHC inlines very massively, to my knowledge. And I think you need this massive inlining for reasonable performance because of Haskell’s high level nature, lazy evaluation, etc. Best wishes, Wolfgang ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: base-4 + gtk2hs-0.10.0 licensing
Am Donnerstag, 26. Februar 2009 20:20 schrieb Achim Schneider: Wolfgang Jeltsch g9ks1...@acme.softbase.org wrote: Am Donnerstag, 26. Februar 2009 09:17 schrieb Ketil Malde: Peter Hercek pher...@gmail.com writes: Relinking against newer Gtk2Hs versions might not work. You have the option of recompiling the new Gtk2Hs with the old GHC and relinking, don't you? Relinking is technically not possible because of inlining. I don't think the situation is any different from providing C headers that contain macros or inline functions. But as Peter Hercek said, the LGPL limits the amount of macro expansion for C libraries. And the amount of GHC’s inlining would probably exceed all limits. ;-) Best wishes, Wolfgang ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANNOUNCE: text and text-icu, fast and comprehensive Unicode support using stream fusion
On Fri, 2009-02-27 at 00:01 -0800, Bryan O'Sullivan wrote: text-icu 0.1 Augments text with comprehensive character set conversion support and normalization (and soon more), via bindings to the ICU library. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/text-icu Excellent! I was just wishing for this two days ago :D 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] ANNOUNCE: text and text-icu, fast and comprehensive Unicode support using stream fusion
Unfortunately it doesn’t build for me. I have libicu-dev 3.8.1 installed. $ cabal install text-icu Resolving dependencies... 'text-icu-0.1' is cached. Configuring text-icu-0.1... Preprocessing library text-icu-0.1... Error.hsc: In function ‘main’: Error.hsc:229: error: ‘U_ARGUMENT_TYPE_MISMATCH’ undeclared (first use in this function) Error.hsc:229: error: (Each undeclared identifier is reported only once Error.hsc:229: error: for each function it appears in.) Error.hsc:230: error: ‘U_DUPLICATE_KEYWORD’ undeclared (first use in this function) Error.hsc:231: error: ‘U_UNDEFINED_KEYWORD’ undeclared (first use in this function) Error.hsc:232: error: ‘U_DEFAULT_KEYWORD_MISSING’ undeclared (first use in this function) Error.hsc:260: error: ‘U_REGEX_OCTAL_TOO_BIG’ undeclared (first use in this function) Error.hsc:261: error: ‘U_REGEX_INVALID_RANGE’ undeclared (first use in this function) Error.hsc:262: error: ‘U_REGEX_STACK_OVERFLOW’ undeclared (first use in this function) Error.hsc:263: error: ‘U_REGEX_TIME_OUT’ undeclared (first use in this function) Error.hsc:264: error: ‘U_REGEX_STOPPED_BY_CALLER’ undeclared (first use in this function) compiling dist/build/Data/Text/ICU/Error_hsc_make.c failed command was: /usr/bin/gcc -c -D__GLASGOW_HASKELL__=610 -I/usr/local/lib/ghc-6.10.1/bytestring-0.9.1.4/include -I/usr/local/lib/ghc-6.10.1/base-4.0.0.0/include -I/usr/local/lib/ghc-6.10.1/include -IPAPI_INCLUDE_DIR dist/build/Data/Text/ICU/Error_hsc_make.c -o dist/build/Data/Text/ICU/Error_hsc_make.o cabal: Error: some packages failed to install: text-icu-0.1 failed during the building phase. The exception was: exit: ExitFailure 1 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] Translating an imperative algorithm - negascout
Toby == Toby Hutton toby.hut...@gmail.com writes: Toby But I don't want to try and refactor the code you've Toby provided without some tests to ensure everything is correct. Toby Rule number one for refactoring. :) A very good reminder. I'll write some simple (data, that is) test cases - I intend to package it as a small library anyway - with type classes so I can plug-in different search algorithms, and it's time I got to grips with HUnit and QuickCheck. Anton It's worth keeping in mind the lesson of the lambda Anton calculus: that a local variable is just a Anton function in disguise. I'd never thought about that before. Thanks to both of you for your suggestions. Most helpful. -- Colin Adams Preston Lancashire ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Coming up with a better API for Network.Socket.recv
On Fri, Feb 27, 2009 at 12:03 AM, Bryan O'Sullivan b...@serpentine.com wrote: On Thu, Feb 26, 2009 at 1:45 PM, Johan Tibell johan.tib...@gmail.com wrote: I find it quite inconvenient to use the `recv` function in Network.Socket as it throws an exception when reaching EOF and there's no way to check whether EOF has been reached before calling `recv`. I agree, the current behaviour is quite unfortunate. In fact, I'm pretty sure I added an entry point named recv_ to network-bytestring to work around precisely this problem. Yes, that's indeed the reason we added it. My current thinking is that we'd drop `recv` from network-bytestring in favor of `recv_`. I've checked how many libraries on Hackage depend on network-bytestring and there are few enough that we could make such a change. It's a bit unfortunate that these libraries have an open dependency on network-bytestring (e.g. network-bytestring = 0.1.1.2). I will contact the maintainers of those libraries before making a new release. There's another problem with the network APIs: they mirror the BSD socket API too faithfully, and provide insufficient type safety. You can try to send on an unconnected socket, and to bind a socket that's already connected, both of which should be statically forbidden. The APIs for datagram-oriented networking ought to be distinct from the stream-oriented variety, I think, even if the underlying C-level calls end up being substantially the same. Really, the big thing that's missing here is enough application of elbow grease from someone who's got a good eye for design and doesn't mind all the slog involved. I think that if someone published a network-alt package (much like the one that was published a few years ago) and tooted their horn vigorously enough, we could put the existing network package out to pasture in fairly short order. I would be interested in trying to create a better API. However, I'm not sure what it would look like. The design space is pretty big. * How can we provide the static guarantees we want? Perhaps with some kind of lightweight monadic regions but if so which definition should we use i.e. can a region return a Socket to the parent region or not? This has implications on how easy the API is to understand. * Should we use enumerators or not? Can they be added as a convenience layer on top of type safe low-level layer? Cheers, Johan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Coming up with a better API for Network.Socket.recv
On Fri, Feb 27, 2009 at 12:07 AM, Achim Schneider bars...@web.de wrote: Bryan O'Sullivan b...@serpentine.com wrote: There's another problem with the network APIs: they mirror the BSD socket API too faithfully, and provide insufficient type safety. You can try to send on an unconnected socket, and to bind a socket that's already connected, both of which should be statically forbidden. The APIs for datagram-oriented networking ought to be distinct from the stream-oriented variety, I think, even if the underlying C-level calls end up being substantially the same. Iteratees to the rescue? Ideally, we'd have a composable IO system that's uniform across different types of IO. I would very much like that. However, even after thinking about the problem for several problems I don't know of a generic definition that feels right. Hopefully someone smarter will come up with one. Cheers, Johan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Coming up with a better API for Network.Socket.recv
2009/2/27 Brandon S. Allbery KF8NH allb...@ece.cmu.edu: On 2009 Feb 26, at 23:41, Achim Schneider wrote: Brandon S. Allbery KF8NH allb...@ece.cmu.edu wrote: On 2009 Feb 26, at 16:45, Johan Tibell wrote: Anyway, the reason recv doesn't return 0 is that if you have a datagram socket, a zero-length recv is valid and doesn't mean EOF. My man page says a retval of 0 means that the peer has performed an orderly shutdown, which, in the UDP case, means that it has send a complete datagram... no mention of EOF. A true EOF in the sense of no more data will be received would mean unbinding the socket. Right. Just have to realize that a zero-length datagram packet is possible and even meaningful, so 0 isn't available as an EOF flag. If this is the case then the Network.Socket module is broken when used for UDP as it throw an exception on receiving a valid message. Anyway, the POSIX spec indicates the EOF condition as return -1 with errno == ECONNRESET; this should not be taken as anything but the limited expressiveness of a C-based API. We should map this return to Nothing. I'm not sure I agree. I think using exceptions in this case is fine as loosing the connection is indeed an exceptional condition and the best thing a program can do in this case is probably to abort processing of the disconnected client. Cheers, Johan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Coming up with a better API for Network.Socket.recv
Anyway, the POSIX spec indicates the EOF condition as return -1 with errno == ECONNRESET; this should not be taken as anything but the limited expressiveness of a C-based API. We should map this return to Nothing. Johan I'm not sure I agree. I think using exceptions in this case is fine as Johan loosing the connection is indeed an exceptional condition and the best Johan thing a program can do in this case is probably to abort processing of Johan the disconnected client. I guess this depends upon how exceptional you want an exception to be. To my mind, a lost connection is a fairly normal condition (FAR to normal for my teleworking situation :-( ). That is, I would expect the exception to occur rather than not, during one run of a program. On that basis, I would suggest Nothing is better than an exception. But I guess it depends upon the program. For long running servers, my expectation above is surely true. But other servers might not share the same expectation. Perhaps it should be configurable? -- Colin Adams Preston Lancashire ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Performance question
The random() function is only marginally better than rand(). On Fri, Feb 27, 2009 at 6:50 AM, Ketil Malde ke...@malde.org wrote: Lennart Augustsson lenn...@augustsson.net writes: C's rand() function is very bad and should never be used really. On Linux (really GNU libc, I suppose) it is the same as random(). But for portability, one is encouraged to spend the two extra letters. I don't understand the details, but I think the Mersenne twister is much better in any case. -k -- If I haven't seen further, it is by standing in the footprints of giants ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Status of Haskell under OsX
Thomas Davie wrote: For me, this worked: sudo port install ghc sudo port install gtk2 sudo port install cairomm curl http://downloads.sourceforge.net/gtk2hs/gtk2hs-0.10.0.tar.gz gtk2hs-0.10.0.tar.gz tar xvfz gtk2hs-0.10.0.tar.gz normal install stuff here. It worked! I had to throw out gtk2, which was present in an incompatible version. Then I did make/make install, and tried compiling a few apps in the demo catalog. Most of them show up, but with these errors: Xlib: extension RANDR missing on display /tmp/launch-UoNAfJ/:0. Xlib: extension Generic Event Extension missing on display /tmp/launch-UoNAfJ/:0. Testing out the demos, it seems it can't find Graphics.UI.Gtk.Glade, Graphics.Rendering.OpenGL System.Gnome.GConf System.Gnome.VFS Media.Streaming.GStreamer Graphics.UI.Gtk.MozEmbed Graphics.UI.Gtk.SourceView Graphics.Rendering.Cairo.SVG Any idea on whether I should: port install some package port install some package + reinstall gtk2hs haskell install some package haskell install some package + reinstall gtk2hs? In pango, I get Layout.hs:41:44: Not in scope: type constructor or class `Event' Layout.hs:42:20: Not in scope: data constructor `Expose' ..but I got that on Windows too. ...and demo/arabic does not show any arabic Bob ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Status of Haskell under OsX
On 27 Feb 2009, at 11:21, Arne Dehli Halvorsen wrote: Thomas Davie wrote: For me, this worked: sudo port install ghc sudo port install gtk2 sudo port install cairomm curl http://downloads.sourceforge.net/gtk2hs/gtk2hs-0.10.0.tar.gz gtk2hs-0.10.0.tar.gz tar xvfz gtk2hs-0.10.0.tar.gz normal install stuff here. It worked! I had to throw out gtk2, which was present in an incompatible version. Then I did make/make install, and tried compiling a few apps in the demo catalog. Most of them show up, but with these errors: Xlib: extension RANDR missing on display /tmp/launch-UoNAfJ/:0. Xlib: extension Generic Event Extension missing on display /tmp/ launch-UoNAfJ/:0. Yep, I see these errors too – even after sudo port install randr. Testing out the demos, it seems it can't find Graphics.UI.Gtk.Glade, Graphics.Rendering.OpenGL System.Gnome.GConf System.Gnome.VFS Media.Streaming.GStreamer Graphics.UI.Gtk.MozEmbed Graphics.UI.Gtk.SourceView Graphics.Rendering.Cairo.SVG Perhaps the demos are out of date? Graphics.Rendering.OpenGL is found in the OpenGL package, and System.Gnome looks unlikely to work on OS X. Bob___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Missing documentation for Haddock
On http://haskell.org/haddock/doc/html/module-attributes.html the not-home attribute is missing (it's documentation is present, but the attribute itself is not named). -- Colin Adams Preston Lancashire ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Missing documentation for Haddock
2009/2/27 Colin Paul Adams co...@colina.demon.co.uk: On http://haskell.org/haddock/doc/html/module-attributes.html the not-home attribute is missing (it's documentation is present, but the attribute itself is not named). Thanks for the report. By the way, the Haddock trac page is at: http://trac.haskell.org/haddock We also have a mailing list: hadd...@projects.haskell.org I will fix this bug directly, so we don't need a bug ticket of course. But it may be nice for you to know where to report bugs in the future. David ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Translating an imperative algorithm - negascout
Am Donnerstag, den 26.02.2009, 20:54 + schrieb Colin Paul Adams: Hello Haskellers, I want to implement the negascout algorithm for the game I'm writing. Wikipedia gives the algorithm in imperative terms: http://en.wikipedia.org/wiki/Negascout I've tried to translate this into Haskell. I'm not sure if I'm going about it the right way, and if I am, if I've done it correctly. Any comments on my effort here, are welcome: A more systematic transformation may lead to a more efficient loop: In the pseudocode, I have replaced the first conditional with the max function and pulled the calculation of (depth - 1) out of the loop: function negascout(node, depth, alpha, beta) if node is a terminal node or depth = 0 return the heuristic value of node b := beta d := depth - 1 foreach child of node alpha := max(alpha, -negascout (child, d, -b, -alpha)) if alpha = beta return alpha if alpha = b alpha := -negascout(child, d, -beta, -alpha) if alpha = beta return alpha b := alpha+1 return alpha In order to make this more Haskell-ish, we assume three self-explaining functions: terminal:: Node - Bool heuristicValue :: Node - Int children:: Node - [a] (Idiomatic) Haskell does not use mutable state or conditionals without else-branch, so we make three modifications: 1) We use pattern matching for the first conditional 2) Every other conditional if c then a rest is rewritten as if c then do a rest else rest and do return x rest is abbreviated as return x (Here, 'return' is the imperative return statement, not the monadic unit) 3) We bring the program into single static assignment form. That is, we introduce new variables, so that every variable is assigned to only once. This is not always possible, because the loop would require us to introduce an unknown number of variables. Therefore, we allow reassignments at the end of an iteration. And there it is, written in Haskell-like pseudocode: negascout :: Node - Int - Int - Int - Int negascout node depth alpha beta | terminal node || depth == 0 = heuristicValue node | otherwise = do b := beta d := depth - 1 foreach child of node do alpha' := max(alpha, - negascout child d (-b) (-alpha)) if alpha' = beta then return alpha' else if alpha' = b then do alpha'' := - negascout child d (-beta) (-alpha') if alpha'' = beta then return alpha'' else do alpha := alpha'' b := alpha'' + 1 else do alpha := alpha' b := alpha' + 1 return alpha Now we see that only alpha and b are modified by the loop. From that it follows how the loop can be turned into a recursive function: This function takes alpha, b and the list of remaining children as its argument: negascout node depth alpha beta | terminal node || depth == 0 = heuristicValue node | otherwise = loop alpha beta (children node) where d = depth - 1 loop alpha b (c:cs) = let alpha' = max(alpha, - negascout c d (-b) (-alpha)) in if alpha' = beta then alpha' else if alpha' = b then let alpha'' = - negascout c d (-beta) (-alpha') in if alpha'' = beta then alpha'' else loop alpha'' (alpha'' + 1) cs else loop alpha' (alpha' + 1) cs loop alpha _ [] = alpha Now you can move around the declarations, introduce some nice guards, optimize the calls where b==alpha+1 or beta==alpha+1 and hunt for hidden folds. (Warning: I didn't test it) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Status of Haskell under OsX
Thomas Davie wrote: Testing out the demos, it seems it can't find Graphics.UI.Gtk.Glade, Graphics.Rendering.OpenGL System.Gnome.GConf System.Gnome.VFS Media.Streaming.GStreamer Graphics.UI.Gtk.MozEmbed Graphics.UI.Gtk.SourceView Graphics.Rendering.Cairo.SVG Perhaps the demos are out of date? Graphics.Rendering.OpenGL is found in the OpenGL package, and System.Gnome looks unlikely to work on OS X. Did a macports install of glade (took ages!), gtkglext, gconf, glut. Reran configure/make/make install for gtk2hs Also did macports install of hs-cabal, then cabal update cabal install opengl cabal install glut Was a little confused for a while because Porticus (ports GUI) was out of date. Maybe I could have installed ghc, hs-cabal + all gtk preconditions, and then installed gtk2hs++ via cabal? Anyway, the opengl demo and the glade demos run now, and if I need mozembed and similar, I trust I will be able to get them in in a similar way. Thanks for helping, I am looking forward to creating GUIs. Bob Arne D Halvorsen ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re[4]: [Haskell-cafe] Re: Incremental array updates
Hello Eugene, Thursday, February 26, 2009, 10:28:13 PM, you wrote: Thanks, I'll have a look at these. Treating unboxed stuff polymorphically is anyways very interesting and would be good to use in collections API that has been recently discussed (and which I occasionally try to continue inventing with scarce success :-/ ). does this mean that type classes from Edison and Container (Collection?) libraries are not good enough or you don't checked them? -- Best regards, Bulatmailto:bulat.zigans...@gmail.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ByteString questions
isn't this sufficient? might require some more Win32 bindings... http://msdn.microsoft.com/en-us/library/ms810467.aspx 2009/2/27 Galchin, Vasili vigalc...@gmail.com ;^) On Thu, Feb 26, 2009 at 11:15 PM, Brandon S. Allbery KF8NH allb...@ece.cmu.edu wrote: On 2009 Feb 26, at 23:58, Galchin, Vasili wrote: i.e. protocol events seem to leak into an application = yuck On Thu, Feb 26, 2009 at 10:57 PM, Galchin, Vasili vigalc...@gmail.comwrote: I already looked at MSDN examples and am not seriously enccouraged ;^( So, next stop: look for a serial library in C (or C++ with appropriate wrappers) for Win32 and make an FFI binding for it. -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allb...@kf8nh.com system administrator [openafs,heimdal,too many hats] allb...@ece.cmu.edu electrical and computer engineering, carnegie mellon universityKF8NH ___ 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: Re[4]: [Haskell-cafe] Re: Incremental array updates
I'm exactly basing on them, but they don't have at least these things: - Monad-mutable collections like MArray - Instances of something like Assoc for arrays (arrays are collections in some sense, after all) - Treatment for unboxed types (I don't know yet, whether it is needed; but why do STUArrays have special treatment then?) It's not that I am in desperate need for these, but making the already-good collection API even better sounds like fun :) Actually, it started with me writing a monad-mutable hashtable and thinking about what its interface should be, so probably I should just upload the hashtable to hackage as is and look what comes next :) 2009/2/27 Bulat Ziganshin bulat.zigans...@gmail.com: Hello Eugene, Thursday, February 26, 2009, 10:28:13 PM, you wrote: Thanks, I'll have a look at these. Treating unboxed stuff polymorphically is anyways very interesting and would be good to use in collections API that has been recently discussed (and which I occasionally try to continue inventing with scarce success :-/ ). does this mean that type classes from Edison and Container (Collection?) libraries are not good enough or you don't checked them? -- Best regards, Bulat mailto:bulat.zigans...@gmail.com -- Eugene Kirpichov Web IR developer, market.yandex.ru ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re[6]: [Haskell-cafe] Re: Incremental array updates
Hello Eugene, Friday, February 27, 2009, 4:42:03 PM, you wrote: I'm exactly basing on them, but they don't have at least these things: them means Edison or Collections typeclasses? - Treatment for unboxed types (I don't know yet, whether it is needed; but why do STUArrays have special treatment then?) imho, this doesn't need its own typeclass Actually, it started with me writing a monad-mutable hashtable and thinking about what its interface should be, so probably I should just upload the hashtable to hackage as is and look what comes next :) what are the differences against Data.Hashtable? -- Best regards, Bulatmailto:bulat.zigans...@gmail.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: ANNOUNCE: pqueue-mtl, stateful-mtl
Ryan Ingram ryani.s...@gmail.com wrote in article 2f9b2d30902151615n1e8e25e8ubbee20d93c8ec...@mail.gmail.com in gmane.comp.lang.haskell.cafe: You can roll your own pure STT monad, at the cost of performance: Do you (or anyone else) know how to prove this STT implementation type-safe? It seems to be safe but I'm not sure how to prove it. -- Edit this signature at http://www.digitas.harvard.edu/cgi-bin/ken/sig A mathematician is a device for turning coffee into theorems. Paul Erdos (1913-1996) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: Re[6]: [Haskell-cafe] Re: Incremental array updates
2009/2/27 Bulat Ziganshin bulat.zigans...@gmail.com: Hello Eugene, Friday, February 27, 2009, 4:42:03 PM, you wrote: I'm exactly basing on them, but they don't have at least these things: them means Edison or Collections typeclasses? The EdisonAPI. - Treatment for unboxed types (I don't know yet, whether it is needed; but why do STUArrays have special treatment then?) imho, this doesn't need its own typeclass I hope so :) Actually, it started with me writing a monad-mutable hashtable and thinking about what its interface should be, so probably I should just upload the hashtable to hackage as is and look what comes next :) what are the differences against Data.Hashtable? Support for ST monad and stuff like insertWith, mergeWith. -- Best regards, Bulat mailto:bulat.zigans...@gmail.com -- Eugene Kirpichov Web IR developer, market.yandex.ru ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Hidden module?
Cabalising hsc2hc I get (this is actually from manually building the package): --- [pa...@bagend hsc2hs-0.67.20061107]$ runghc Setup.hs build Preprocessing executables for hsc2hs-0.67.20061107... Building hsc2hs-0.67.20061107... Main.hs:32:7: Could not find module `System.Process': it is a member of package process-1.0.1.0, which is hidden [pa...@bagend hsc2hs-0.67.20061107]$ which I cannot understand. Please help! --- Cristiano ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Status of Haskell under OsX
On Fri, Feb 27, 2009 at 12:04 AM, Thomas Davie tom.da...@gmail.com wrote: On 27 Feb 2009, at 08:17, Arne Dehli Halvorsen wrote: Manuel M T Chakravarty wrote: I'm planning to purchase a MacBookPro so I'm wondering how well Haskell is supported under this platform. At least two of the regular contributors to GHC work on Macs. That should ensure that Mac OS X is well supported. Installation is trivial with the Mac OS X installer package: http://haskell.org/ghc/download_ghc_6_10_1.html#macosxintel Good advice, but I've generally found the MacPorts version more consistantly built – plus, sudo port install ghc is nice and easy :) Does the MacPort have GMP linked statically or dynamically? I haven't gotten around to trying to build things with a dynamic libgmp yet... but it's not fun to have LGPL statically linked stuff if you care about your own licensing terms. Hi, following on from this point: How does one get gtk2hs running on a mac? I have a MacBook Pro, and I've had ghc installed for some time now. (first in 6.8.2 (packaged), then 6.10.1 (packaged), then 6.8.2 via macports 1.6 then 6.10.1 via macports 1.7) I tried to install gtk2hs via macports, but it didn't work. (0.9.12? on 6.8.2, then on 6.10.1) Is there a recipe one could follow? Can I get the preconditions via macports, and then use cabal to install gtk2hs 0.10? For me, this worked: sudo port install ghc sudo port install gtk2 sudo port install cairomm curl http://downloads.sourceforge.net/gtk2hs/gtk2hs-0.10.0.tar.gz gtk2hs-0.10.0.tar.gz tar xvfz gtk2hs-0.10.0.tar.gz normal install stuff here. Bob___ 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] Hidden module?
Am Freitag, 27. Februar 2009 15:13 schrieb Cristiano Paris:
Cabalising hsc2hc I get (this is actually from manually building the
package):
---
[pa...@bagend hsc2hs-0.67.20061107]$ runghc Setup.hs build
Preprocessing executables for hsc2hs-0.67.20061107...
Building hsc2hs-0.67.20061107...
Main.hs:32:7:
Could not find module `System.Process':
it is a member of package process-1.0.1.0, which is hidden
[pa...@bagend hsc2hs-0.67.20061107]$
which I cannot understand. Please help!
---
Cristiano
Cabal hides all packages not listed among the build-depends when building the
libraries. I think in 2006, System.Process was in the base package ('twas
before the base-split), so process is not listed among the build-depends in
hsc2hs' .cabal file.
Add it and try again.
Cheers,
Daniel
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Re: [Haskell-cafe] ANNOUNCE: text and text-icu, fast and comprehensive Unicode support using stream fusion
2009/2/27 Bryan O'Sullivan b...@serpentine.com: On behalf of the Data.Text team, I am delighted to announce the release of preview versions of two new packages: text 0.1 Fast, packed Unicode text support, using a modern stream fusion framework. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/text This is a nice news. What is the preferred way to parse some Text ? Thanks, Thu ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: [darcs-users] darcs and Google Summer of Code
Hi, (carefully avoiding your name :-P) On Mon, Feb 23, 2009 at 16:08:18 +0100, Wolfgang Jeltsch wrote: Tomorrow, I will discuss with the first half of my student project students (3 students) about what exact topic they will pursue. My idea is to let them start a Grapefruit-based darcs GUI. They should not use the currenct darcs interface directly where it doesn’t fit GUI frontends well. Instead they should write a wrapper around the “ugly” parts which exposes a “nice” interface. Later, one could merge this wrapper into the darcs codebase so that darcs exports the “nice” interface then. The GUI code wouldn’t have to change much then. It would be interesting to see how they get on writing their wrapper around the darcs library as opposed to making darcs invocations (although if you were to go the latter route, I noticed that the patch-tag folks have uploaded a 'DarcsHelpers' package which may be of some use. In April, the second half of the students will start with their project. If there is some graphics support in Grapefruit at that time then they might work on a patch viewer. What do you think about that? In addition to my previous suggestion that the students hang out in #darcs, maybe they could start some sort of blog detailing their progress, and with the occasional screenshot? It would be a great addition to the darcs planet: http://planet.darcs.net Thanks! -- Eric Kow http://www.nltg.brighton.ac.uk/home/Eric.Kow PGP Key ID: 08AC04F9 signature.asc Description: Digital signature ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Strict version of Data.Map.map
I guess so. Maybe using mapAccum helps: import qualified Data.Map as M strictMap :: (a - b) - M.Map k a - M.Map k b strictMap f m = case M.mapAccum f' () m of ((), m') - m' where f' () x = x' `seq` ((), x') where x' = f x testStrictness mapper = m `seq` Not strict. where m = mapper (const e) (M.singleton () ()) e = error Strict! :: () Very clever. I had tried to use mapAccum but I couldn't figure out what to put in the accumulator. I didn't realize it didn't make a difference (unit will do) as long as it is evaluated when the Map is. Seq wrecks my head ;) Thanks! Edsko ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Sparse vector operations
Hi all, In a couple of my projects I have needed to perform operations on (very) sparse vectors. I came up with the attached simple module which defines a typeclass and implements instances for simple and nested (Int)Maps. Is this the right way to go about it? Am I reinventing some wheels? Comments welcome. Best, -- Grzegorz http://www.nabble.com/file/p22247686/SparseVector.hs SparseVector.hs -- View this message in context: http://www.nabble.com/Sparse-vector-operations-tp22247686p22247686.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] ANNOUNCE: text and text-icu, fast and comprehensive Unicode support using stream fusion
2009/2/27 minh thu not...@gmail.com: 2009/2/27 Bryan O'Sullivan b...@serpentine.com: On behalf of the Data.Text team, I am delighted to announce the release of preview versions of two new packages: text 0.1 Fast, packed Unicode text support, using a modern stream fusion framework. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/text This is a nice news. What is the preferred way to parse some Text ? I mean it is straightforward to rewrite attoparsec to use Text instead of (Lazy and Strict) Bytestring, but is it the way to go ? Thanks, Thu ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Trouble building ArrayRef 0.1.3
Hi When I try to build ArrayRef 0.1.3 I get: Control/Concurrent/LockingBZ.hs:159:54: Ambiguous type variable `e' in the constraint: `Exception e' arising from a use of `throw' at Control/Concurrent/LockingBZ.hs:159:54-60 Probable fix: add a type signature that fixes these type variable(s) I am compiling with: runhaskell Setup.hs build I run Debian Linux with GHC 6.10.1. Anybody has a solution for my problem? Greetings, Mads Lindstrøm ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Hidden module?
On Fri, Feb 27, 2009 at 3:19 PM, Daniel Fischer
daniel.is.fisc...@web.de wrote:
Cabal hides all packages not listed among the build-depends when building the
libraries. I think in 2006, System.Process was in the base package ('twas
before the base-split), so process is not listed among the build-depends in
hsc2hs' .cabal file.
Add it and try again.
I had to append process and directory as dependencies but then it
worked. How can I submit a patch to Hackage? Do I have to contact the
owner?
Cristiano
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Re: [Haskell-cafe] Trouble building ArrayRef 0.1.3
Hello Mads, Friday, February 27, 2009, 6:27:52 PM, you wrote: i made this lib back in the ghc 6.4 days, so it probably have a lot of compatibility problems here and there :( i'm self still use ghc 6.6 :) When I try to build ArrayRef 0.1.3 I get: Control/Concurrent/LockingBZ.hs:159:54: Ambiguous type variable `e' in the constraint: `Exception e' arising from a use of `throw' at Control/Concurrent/LockingBZ.hs:159:54-60 Probable fix: add a type signature that fixes these type variable(s) I am compiling with: runhaskell Setup.hs build I run Debian Linux with GHC 6.10.1. Anybody has a solution for my problem? Greetings, Mads Lindstrøm ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- Best regards, Bulatmailto:bulat.zigans...@gmail.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANNOUNCE: text and text-icu, fast and comprehensive Unicode support using stream fusion
On Fri, Feb 27, 2009 at 12:57 AM, George Pollard por...@porg.es wrote: Unfortunately it doesn’t build for me. I have libicu-dev 3.8.1 installed. Yes, as the README states, the text-icu package needs ICU 4.0. The basic text library has no such external dependencies. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Data.Binary, strict reading
On Thu, 2009-02-26 at 09:17 +, Neil Mitchell wrote: I suggest you use withFile instead and decode from the Handle that gives you (via hGetContents) rather than decodeFile from the file name. That makes it much clearer. Of course you have to avoid doing lazy stuff, but that should be ok, Binary is strict in reading by default. That was my first attempt, but the types didn't match up. I can withFile using a System.IO handle, but Data.Binary doesn't seem to be able to start going from a Handle. I guess I have to hop via the ByteString bit myself with hGetContents. That's perfectly fine, and much better than currently. However Yes, you would use hGetContents. readDB = io $ (dbLocation = r) `catch` (λ_ → return empty) where r x = fmap (decode · BL.fromChunks · return) $ B.readFile x This seems to be a very nice way of doing it, the strictness is explicit in the ByteString.readFile. I've gone for this in my code. I still think my suggestion was nicer. It makes the resource boundedness completely explicit, not relying on any strictness properties. It also doesn't unnecessarily read the whole file into memory before processing, though I expect for your example that doesn't matter too much. Duncan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] differences between Data.Array and Data.Vector
manlio_perillo: Hi. In Hackage there are some packages named *array*, and others named *vector*. What are the differences? Is available a guide to the various data structures available in Haskell? The vector packages tend to be either easily growable, or easily fusible, or both. There's no clear convention though. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: ANNOUNCE: pqueue-mtl, stateful-mtl
Hmm, that's a really good question now that you mention it. So, the implementation given is trivially *not* type-safe; eventually the Int index will wrap around and reuse indices at the potentially wrong type. But lets say you replaced IntMap with Map Integer, to avoid this problem. A simple property: STTRefs cannot escape to another STT session. Proof: See SPJ's original ST paper. This is actually kind of useful on its own, because you can nest STTs over each other to provide something like regions. Then it comes down to, within a session, is there some way for an STTRef to mingle and break the type-safety rule. I can think of two potential ways this might happen. First, if the underlying monad is something like List or Logic, there may be a way for STTRefs to move between otherwise unrelated branches of the computation. Second, if the underlying monad is something like Cont, there may be a way for an STTRef to get transmitted back in time via a continuation to a point where it hadn't been allocated yet. So if there is a counterexample I expect it to come down to one of those two cases. -- ryan On Thu, Feb 26, 2009 at 11:22 PM, Chung-chieh Shan ccs...@post.harvard.edu wrote: Ryan Ingram ryani.s...@gmail.com wrote in article 2f9b2d30902151615n1e8e25e8ubbee20d93c8ec...@mail.gmail.com in gmane.comp.lang.haskell.cafe: You can roll your own pure STT monad, at the cost of performance: Do you (or anyone else) know how to prove this STT implementation type-safe? It seems to be safe but I'm not sure how to prove it. -- Edit this signature at http://www.digitas.harvard.edu/cgi-bin/ken/sig A mathematician is a device for turning coffee into theorems. Paul Erdos (1913-1996) ___ 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
[Haskell-cafe] Making the pointfree package work with cabal
Today I was very happy to discover the pointfree package, since lambdabot unfortunately doesn't work on Windows. The package works just fine, but the installation process is less than ideal. cabal install pointfree doesn't work and to install it manually you have to add containers and array to the build-depends list in the cabal file. To get rid of the warning about the build type you have to add build-type: Simple. I asked in the IRC channel what the best course of action was to fix this and they referred me here. The author of the package is Thomas Jäger, who should go by the IRC name TheHunter. I would hereby like to ask him to make these small changes and upload a new version, or to give me or someone else permission to do so. Regards, Remco Niemeijer ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Trouble building ArrayRef 0.1.3
Hi For anyone who may care, I have googled a workaround. The problem below is similar to the problem mentioned here http://stackoverflow.com/questions/431527/ambiguous-type-variable-error-msg . I wrote: Hi When I try to build ArrayRef 0.1.3 I get: Control/Concurrent/LockingBZ.hs:159:54: Ambiguous type variable `e' in the constraint: `Exception e' arising from a use of `throw' at Control/Concurrent/LockingBZ.hs:159:54-60 Probable fix: add a type signature that fixes these type variable(s) I am compiling with: runhaskell Setup.hs build I run Debian Linux with GHC 6.10.1. Anybody has a solution for my problem? Greetings, Mads Lindstrøm /Mads ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re[2]: [Haskell-cafe] Trouble building ArrayRef 0.1.3
Hello Mads, Friday, February 27, 2009, 10:08:17 PM, you wrote: http://haskell.org/haskellwiki/Upgrading_packages is more appropriate, see 2.3 Hi For anyone who may care, I have googled a workaround. The problem below is similar to the problem mentioned here http://stackoverflow.com/questions/431527/ambiguous-type-variable-error-msg I wrote: Hi When I try to build ArrayRef 0.1.3 I get: Control/Concurrent/LockingBZ.hs:159:54: Ambiguous type variable `e' in the constraint: `Exception e' arising from a use of `throw' at Control/Concurrent/LockingBZ.hs:159:54-60 Probable fix: add a type signature that fixes these type variable(s) I am compiling with: runhaskell Setup.hs build I run Debian Linux with GHC 6.10.1. Anybody has a solution for my problem? Greetings, Mads Lindstrøm /Mads ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- Best regards, Bulatmailto:bulat.zigans...@gmail.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Sparse vector operations
Grzegorz Chrupala wrote: Hi all, In a couple of my projects I have needed to perform operations on (very) sparse vectors. I came up with the attached simple module which defines a typeclass and implements instances for simple and nested (Int)Maps. Is this the right way to go about it? Am I reinventing some wheels? Comments welcome. Best, -- Grzegorz http://www.nabble.com/file/p22247686/SparseVector.hs SparseVector.hs I've been working on a matrix/vector library over the last month. The matrices are implemented as QuadTrees, using block decomposition techniques for various algorithms. Vectors were kind of an afterthought, but they are implemented as binary trees - the thought being that they would decompose symmetrically with matrices. Sparsity comes free with this approach (more or less), and is already implemented. Divide and conquer based parallelism should fit nicely into the mix too, but i haven't got to that point. From what I've tested so far, the performance is about the same as hmatrix and the various other matrix libraries on hackage. I've been trying to implement stream fusion for it over the last couple of days, but haven't been able to get it working right - maybe Dons can offer some advice. For testing purposes, the uvector fusion based flat-matrix addition is twice as fast: add a b = mapU (uncurryU (+)) $ zipU a b With the tree based code, profiling shows matrix (*) and (+) perform a decent amount of memory allocation, so fusion should provide a big win i think. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Sparse vector operations
Neal Alexander wrote: Grzegorz Chrupala wrote: Hi all, In a couple of my projects I have needed to perform operations on (very) sparse vectors. I came up with the attached simple module which defines a typeclass and implements instances for simple and nested (Int)Maps. Is this the right way to go about it? Am I reinventing some wheels? Comments welcome. Best, -- Grzegorz http://www.nabble.com/file/p22247686/SparseVector.hs SparseVector.hs I've been working on a matrix/vector library over the last month. The matrices are implemented as QuadTrees, using block decomposition techniques for various algorithms. Vectors were kind of an afterthought, but they are implemented as binary trees - the thought being that they would decompose symmetrically with matrices. Sparsity comes free with this approach (more or less), and is already implemented. Divide and conquer based parallelism should fit nicely into the mix too, but i haven't got to that point. From what I've tested so far, the performance is about the same as hmatrix and the various other matrix libraries on hackage. I've been trying to implement stream fusion for it over the last couple of days, but haven't been able to get it working right - maybe Dons can offer some advice. For testing purposes, the uvector fusion based flat-matrix addition is twice as fast: add a b = mapU (uncurryU (+)) $ zipU a b With the tree based code, profiling shows matrix (*) and (+) perform a decent amount of memory allocation, so fusion should provide a big win i think. Forgot to link the code: http://community.haskell.org/~hexpuem/bdMatrix/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Hidden module?
Cristiano Paris cristiano.pa...@gmail.com wrote: I had to append process and directory as dependencies but then it worked. How can I submit a patch to Hackage? Do I have to contact the owner? In general, just try the maintainer and/or author adresses given on hsc2hs's hackage page. I'd advice you to switch over to c2hs, which is actively developed, while hsc2hs's last update date smells like abandonware. -- (c) this sig last receiving data processing entity. Inspect headers for copyright history. All rights reserved. Copying, hiring, renting, performance and/or quoting of this signature prohibited. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] How can you effectively manually determine the type?
Hello, I'm new at haskell and I have the following question: let's say I type the following: function = foldr until Now my first question is what is the type of this function? Well let's see what the type of until and foldr is: until :: (a - Bool) - (a - a) - a - a foldr :: (a - b - b) - b - [a] - b So I would be thinking: we fill until in the position of (a - b - b) so, a correspond with (a - Bool) and b correspond with (a - a) and b correspond with a. Hmm a small problem, I think we can divide that as follows: b1 corresponds with (a - a) and b2 corresponds with a. So I get: foldr until :: b1 - [a] - b2 foldr until :: (a - a) - [a - Bool] - a Is this a correct way of thinking or am I wrong? And another question is: can someone give me an example how this can be executed? All my code that I tried to execute resulted in errors with foldr until. Thanks! ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Samples for http package
Hi everyone, are there any examples on how to use the current version of the http package? Günther ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] memory issues
bulat.ziganshin:
Hello Rogan,
Saturday, February 28, 2009, 1:18:47 AM, you wrote:
data Block = Block {
offset::Integer
, size::Integer
} deriving (Eq)
try
!offset::Integer
, !size::Integer
offset :: !Integer
And possibly just using {-# UNPACK #-}!Int64 would be ok?
-- Don
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Re: [Haskell-cafe] memory issues
Am Samstag, 28. Februar 2009 00:37 schrieb Bulat Ziganshin: Hello Daniel, Saturday, February 28, 2009, 2:21:31 AM, you wrote: printf %s $ unlines $ map (show) (sort $! blocks content) Bad! Use mapM_ print $ sort $ blocks content are you sure? Tested it. The printf %s is very bad. Replacing that reduced allocation and GC time by a factor of 2+. The difference between mapM_ print and putStr $ unlines $ map show $ ... is too small for me to be sure that mapM_ print is really better. print may waste a lot of time, locking stdout for every line printed Hm, maybe main = do args - getArgs content - B.readFile (args!!0) hout - openFile (args!!1) WriteMode mapM_ (hPrint hout) $ sort $ blocks content hClose hout ? I find hardly any difference, though. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Incremental array updates
I'm still learning haskell, so I may be missing something pretty obvious, but isn't this the kind of thing that the diff array types were created for. http://en.wikibooks.org/wiki/Haskell/Hierarchical_libraries/Arrays#DiffArray_.28module_Data.Array.Diff.29 -Keith On Thu, Feb 26, 2009 at 06:45:27PM +, Ross Paterson wrote: Yes, bucketing problems like this are a common case that the standard functions cannot handle. Perhaps the libraries need a canned solution. Stratch that -- as Bulat points out, accumArray is such a canned solution. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Translating an imperative algorithm - negascout
Holger Siegel wrote: loop alpha b (c:cs) = let alpha' = max(alpha, - negascout c d (-b) (-alpha)) in if alpha' = beta then alpha' else if alpha' = b then let alpha'' = - negascout c d (-beta) (-alpha') in if alpha'' = beta then alpha'' else loop alpha'' (alpha'' + 1) cs else loop alpha' (alpha' + 1) cs loop alpha _ [] = alpha Guard-izing and where-izing that for more clarity: loop alpha _ [] = alpha loop alpha b (c:cs) = result where alpha' = max(alpha, - negascout c d (-b) (-alpha)) result | alpha' = beta = alpha' | alpha' = b = result' | otherwise = loop alpha' (alpha' + 1) cs where result' | alpha'' = beta = alpha'' | otherwise = loop alpha'' (alpha'' + 1) cs where alpha'' = - negascout c d (-beta) (-alpha') Which makes it obvious that the result function is something inlined into itself. Uninlining may make the code clearer still, or maybe not. -- Live well, ~wren ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: ANNOUNCE: pqueue-mtl, stateful-mtl
I note that all of your broken issues revolve around calls that can't be written in terms of lift; that is, you need access to the STT constructor in order to create these problems. It's obvious that anything that accesses the STT constructor will potentially not be typesafe; the question I have is that whether you can construct something that isn't typesafe just via the use of runSTT lift. If you wanted to implement callCC directly (as opposed to lift . callCC) you would need to be extremely careful, as you noticed. -- ryan On Fri, Feb 27, 2009 at 2:27 PM, David Menendez d...@zednenem.com wrote: On Fri, Feb 27, 2009 at 1:28 PM, Ryan Ingram ryani.s...@gmail.com wrote: Then it comes down to, within a session, is there some way for an STTRef to mingle and break the type-safety rule. I can think of two potential ways this might happen. First, if the underlying monad is something like List or Logic, there may be a way for STTRefs to move between otherwise unrelated branches of the computation. Second, if the underlying monad is something like Cont, there may be a way for an STTRef to get transmitted back in time via a continuation to a point where it hadn't been allocated yet. I think promoting MonadPlus would be safe. The code for mplus will end up looking something like: mplus (STT a) (STT b) = STT (StateT (\heap - runStateT a heap `mplus` runStateT b heap)) so each branch is getting its own copy of the heap. The fancier logic stuff, like msplit, doesn't promote well through StateT, and isn't type-safe in STT For example: class (MonadPlus m) = ChoiceMonad m where msplit :: m a - m (Maybe (a, m a)) instance ChoiceMonad [] where msplit [] = [Nothing] msplit (x:xs) = [Just (x,xs)] There are at least two ways to promote msplit through StateT. The method I used in my library is, instance (ChoiceMonad m) = ChoiceMonad (StateT s m) where msplit m = StateT $ \s - msplit (runStateT m s) = return . maybe (Nothing, s) (\ ((a,s'),r) - (Just (a, StateT (\_ - r)), s')) If you promoted that instance through STT, it would no longer be safe. test = do Just (_, rest) - msplit $ mplus (return ()) (return ()) ref1 - newSTTRef 'a' rest ref2 - newSTTRef (65 :: Int) readSTTRef ref1 The call to rest effectively undoes the first call to newSTTRef, so that ref1 and ref2 end up referring to the same cell in the heap. I'm confident callCC and shift will cause similar problems. -- Dave Menendez d...@zednenem.com http://www.eyrie.org/~zednenem/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Incremental array updates
It is, but they are still too slow. STArrays rock the world. 2009/2/28 Keith Sheppard keiths...@gmail.com: I'm still learning haskell, so I may be missing something pretty obvious, but isn't this the kind of thing that the diff array types were created for. http://en.wikibooks.org/wiki/Haskell/Hierarchical_libraries/Arrays#DiffArray_.28module_Data.Array.Diff.29 -Keith On Thu, Feb 26, 2009 at 06:45:27PM +, Ross Paterson wrote: Yes, bucketing problems like this are a common case that the standard functions cannot handle. Perhaps the libraries need a canned solution. Stratch that -- as Bulat points out, accumArray is such a canned solution. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- Eugene Kirpichov Web IR developer, market.yandex.ru ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
