[Haskell-cafe] cabal: internal error when reading package index
L.S., I was trying to install a package from a local drive and got the following message: cabal install Resolving dependencies... cabal: internal error when reading package index: could not read tar file entryThe package index or index cache is probably corrupt. Running cabal update might fix it. Then I tried cabal update: cabal update Downloading the latest package list from hackage.haskell.org Skipping download: Local and remote files match. Note: there is a new version of cabal-install available. To upgrade, run: cabal install cabal-install Trying the command cabal install cabal-install gave the same internal error message as for the first command. What can I do about this? Regards, Henk-Jan van Tuyl -- Folding@home What if you could share your unused computer power to help find a cure? In just 5 minutes you can join the world's biggest networked computer and get us closer sooner. Watch the video. http://folding.stanford.edu/ http://Van.Tuyl.eu/ http://members.chello.nl/hjgtuyl/tourdemonad.html Haskell programming -- ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] cabal: internal error when reading package index
On 18 September 2013 19:23, Henk-Jan van Tuyl hjgt...@chello.nl wrote: L.S., I was trying to install a package from a local drive and got the following message: cabal install Resolving dependencies... cabal: internal error when reading package index: could not read tar file entryThe package index or index cache is probably corrupt. Running cabal update might fix it. Then I tried cabal update: cabal update Downloading the latest package list from hackage.haskell.org Skipping download: Local and remote files match. Note: there is a new version of cabal-install available. To upgrade, run: cabal install cabal-install Trying the command cabal install cabal-install gave the same internal error message as for the first command. What can I do about this? Maybe try deleting the current download? Namely ~/.cabal/packages/hackage.haskell.org/00-index.* Regards, Henk-Jan van Tuyl -- Folding@home What if you could share your unused computer power to help find a cure? In just 5 minutes you can join the world's biggest networked computer and get us closer sooner. Watch the video. http://folding.stanford.edu/ http://Van.Tuyl.eu/ http://members.chello.nl/hjgtuyl/tourdemonad.html Haskell programming -- ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com http://IvanMiljenovic.wordpress.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Multi-param typeclass vs locally constrained typeclass methods
Could someone please explain what the difference (if any!), in semantics is between class Foo f = Bar f g where method1 :: f a - g a and class Bar' g where method2 :: Foo f = f a - g a ? Maybe the translation of the above to something lower level might help. [Note: f a - g a is just an example, and is not meaningful to the question]. The best answer would contain a design guideline for typeclasses, which would spell out conditions in which to use each variant. Jacques ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Multi-param typeclass vs locally constrained typeclass methods
* Jacques Carette care...@mcmaster.ca [2013-09-18 08:21:51-0400] Could someone please explain what the difference (if any!), in semantics is between class Foo f = Bar f g where method1 :: f a - g a and class Bar' g where method2 :: Foo f = f a - g a Bar is more flexible than Bar'. If you have n types, you can write n^2 Bar instances (potentially having very different semantics) to convert between them. You can only write n Bar' instances, on the other hand. In these instances you can dispatch based on 'g' but not on 'f'. 'f' is abstract, and you only can access it through the Foo interface. So they are quite different. Roman signature.asc Description: Digital signature ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] future (editor) of HCAR?
Dear all, The Haskell Communities and Activities Report has been produced twice a year for more than ten years now: http://www.haskell.org/haskellwiki/Haskell_Communities_and_Activities_Report I have been responsible for producing it the last few years, which was fun. I am now looking to pass that on, handing over the HCAR to someone else. Any takers? Editing HCAR is a few days work per year, but it is also a great way to be involved in the Haskell community - you get a lot of news first hand. There are various procedures in place that automate some of the work, and if someone is interested in taking over, I'm very willing to help along, for example producing the next edition of the report together for a smooth transition. Below I attach the previous call for contributions, which also answers some basic questions about the report. For further questions about the process etc., anybody interested simply get in touch with me. Also, such a transition is a good opportunity to rethink model and processes. Maybe you (anybody on the mailing list) have completely new ideas for how the HCAR should be organized? How it could function better? What other purposes it could serve than it has so far? ... (Or even that HCAR in its existing form is not needed anymore, but could be replaced by something great new?) Best, Janis. Original-Nachricht Betreff: Call for Contributions - Haskell Communities and Activities Report, May 2013 edition Datum: Mon, 08 Apr 2013 21:56:19 +0200 Von: Janis Voigtländer j...@informatik.uni-bonn.de An: Haskell hask...@haskell.org Dear all, I would like to collect contributions for the 24th edition of the Haskell Communities Activities Report http://www.haskell.org/haskellwiki/Haskell_Communities_and_Activities_Report Submission deadline: 1 May 2013 (please send your contributions to hcar at haskell.org, in plain text or LaTeX format) This is the short story: * If you are working on any project that is in some way related to Haskell, please write a short entry and submit it. Even if the project is very small or unfinished or you think it is not important enough --- please reconsider and submit an entry anyway! * If you are interested in an existing project related to Haskell that has not previously been mentioned in the HCAR, please tell me, so that I can contact the project leaders and ask them to submit an entry. * Feel free to pass on this call for contributions to others that might be interested. More detailed information: The Haskell Communities Activities Report is a bi-annual overview of the state of Haskell as well as Haskell-related projects over the last, and possibly the upcoming six months. If you have only recently been exposed to Haskell, it might be a good idea to browse the previous edition --- you will find interesting projects described as well as several starting points and links that may provide answers to many questions. Contributions will be collected until the submission deadline. They will then be compiled into a coherent report that is published online as soon as it is ready. As always, this is a great opportunity to update your webpages, make new releases, announce or even start new projects, or to talk about developments you want every Haskeller to know about! Looking forward to your contributions, Janis (current editor) FAQ: Q: What format should I write in? A: The required format is a LaTeX source file, adhering to the template that is available at: http://haskell.org/communities/05-2013/template.tex There is also a LaTeX style file at http://haskell.org/communities/05-2013/hcar.sty that you can use to preview your entry. If you do not know LaTeX, then use plain text. If you modify an old entry that you have written for an earlier edition of the report, you should already have received your old entry as a template (provided I have your valid email address). Please modify that template, rather than using your own version of the old entry as a template. Q: Can I include Haskell code? A: Yes. Please use lhs2tex syntax (http://people.cs.uu.nl/andres/lhs2tex/). The report is compiled in mode polycode.fmt. Q: Can I include images? A: Yes, you are even encouraged to do so. Please use .jpg format, then. Q: Should I send files in .zip archives or similar? A: No, plain file attachements are the way. Q: How much should I write? A: Authors are asked to limit entries to about one column of text. A general introduction is helpful. Apart from that, you should focus on recent or upcoming developments. Pointers to online content can be given for more comprehensive or historic overviews of a project. Images do not count towards the length limit, so you may want to use this opportunity to pep up entries. There is no minimum
Re: [Haskell-cafe] future (editor) of HCAR?
I would be delighted to take the full responsibility (or just help) in the HCAR. I have some ideas, maybe I could get some time later to write them down. 2013/9/18 Janis Voigtlaender j...@informatik.uni-bonn.de Dear all, The Haskell Communities and Activities Report has been produced twice a year for more than ten years now: http://www.haskell.org/**haskellwiki/Haskell_**Communities_and_Activities_ **Reporthttp://www.haskell.org/haskellwiki/Haskell_Communities_and_Activities_Report I have been responsible for producing it the last few years, which was fun. I am now looking to pass that on, handing over the HCAR to someone else. Any takers? Editing HCAR is a few days work per year, but it is also a great way to be involved in the Haskell community - you get a lot of news first hand. There are various procedures in place that automate some of the work, and if someone is interested in taking over, I'm very willing to help along, for example producing the next edition of the report together for a smooth transition. Below I attach the previous call for contributions, which also answers some basic questions about the report. For further questions about the process etc., anybody interested simply get in touch with me. Also, such a transition is a good opportunity to rethink model and processes. Maybe you (anybody on the mailing list) have completely new ideas for how the HCAR should be organized? How it could function better? What other purposes it could serve than it has so far? ... (Or even that HCAR in its existing form is not needed anymore, but could be replaced by something great new?) Best, Janis. Original-Nachricht Betreff: Call for Contributions - Haskell Communities and Activities Report, May 2013 edition Datum: Mon, 08 Apr 2013 21:56:19 +0200 Von: Janis Voigtländer j...@informatik.uni-bonn.de An: Haskell hask...@haskell.org Dear all, I would like to collect contributions for the 24th edition of the ==**==** Haskell Communities Activities Report http://www.haskell.org/**haskellwiki/Haskell_**Communities_and_Activities_ **Reporthttp://www.haskell.org/haskellwiki/Haskell_Communities_and_Activities_Report Submission deadline: 1 May 2013 (please send your contributions to hcar at haskell.org, in plain text or LaTeX format) ==**==** This is the short story: * If you are working on any project that is in some way related to Haskell, please write a short entry and submit it. Even if the project is very small or unfinished or you think it is not important enough --- please reconsider and submit an entry anyway! * If you are interested in an existing project related to Haskell that has not previously been mentioned in the HCAR, please tell me, so that I can contact the project leaders and ask them to submit an entry. * Feel free to pass on this call for contributions to others that might be interested. More detailed information: The Haskell Communities Activities Report is a bi-annual overview of the state of Haskell as well as Haskell-related projects over the last, and possibly the upcoming six months. If you have only recently been exposed to Haskell, it might be a good idea to browse the previous edition --- you will find interesting projects described as well as several starting points and links that may provide answers to many questions. Contributions will be collected until the submission deadline. They will then be compiled into a coherent report that is published online as soon as it is ready. As always, this is a great opportunity to update your webpages, make new releases, announce or even start new projects, or to talk about developments you want every Haskeller to know about! Looking forward to your contributions, Janis (current editor) FAQ: Q: What format should I write in? A: The required format is a LaTeX source file, adhering to the template that is available at: http://haskell.org/**communities/05-2013/template.**texhttp://haskell.org/communities/05-2013/template.tex There is also a LaTeX style file at http://haskell.org/**communities/05-2013/hcar.styhttp://haskell.org/communities/05-2013/hcar.sty that you can use to preview your entry. If you do not know LaTeX, then use plain text. If you modify an old entry that you have written for an earlier edition of the report, you should already have received your old entry as a template (provided I have your valid email address). Please modify that template, rather than using your own version of the old entry as a template. Q: Can I include Haskell code? A: Yes. Please use lhs2tex syntax (http://people.cs.uu.nl/** andres/lhs2tex/ http://people.cs.uu.nl/andres/lhs2tex/). The report is compiled in mode polycode.fmt.
Re: [Haskell-cafe] Multi-param typeclass vs locally constrained typeclass methods
On 13-09-18 08:54 AM, Roman Cheplyaka wrote: * Jacques Carette care...@mcmaster.ca [2013-09-18 08:21:51-0400] Could someone please explain what the difference (if any!), in semantics is between class Foo f = Bar f g where method1 :: f a - g a and class Bar' g where method2 :: Foo f = f a - g a Bar is more flexible than Bar'. If you have n types, you can write n^2 Bar instances (potentially having very different semantics) to convert between them. You can only write n Bar' instances, on the other hand. In these instances you can dispatch based on 'g' but not on 'f'. 'f' is abstract, and you only can access it through the Foo interface. So they are quite different. Right, that makes sense, thanks. Turns out that, in my case, I frequently want the Bar' case, as I want things to be fully polymorphic in Foo. Jacques ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] OS X ghci problem
The ghci bug goes away when you use a ghc head snapshot from late summer? Great! On Wednesday, September 18, 2013, Jan-Philip Loos wrote: Sadly I was not able to use your build directly, because ghc(i) searched libs in a invalid path (it seems to be wired to one of your directories). I tried to build this ghc version from source on my own, without success beyond stage 1. This [1] is related to the build failure. I tried new alex and happy versions, without any change. A naive approach was to compile alex/happy with ghc_stage1 compiler, without success (as I expected due missing TH). I tried several ghc versions for bootstrapping and alex/happy rebuilding (i guess ghc 7.6 is necessary for a valid 7.7 alex/happy build with the new Bool primops), without success too. Finally I ended in a fully self build ghc 7.7.20130730 ([2]) and with this ghc I can confirm that this specific error with Binding.GLFW.c'glfwInit is gone :) Thanks [1] http://www.mail-archive.com/ghc-devs@haskell.org/msg02357.html [2] http://darcs.haskell.org/ghcBuilder/uploads/tn23/ghc-7.7.20130730-src.tar.bz2 On Mon, Sep 16, 2013 at 2:52 PM, Christiaan Baaij christiaan.ba...@gmail.com javascript:; wrote: Here's a binary dist of my build: https://www.dropbox.com/s/d37rij0dnvjiqqy/ghc-7.7.20130915-x86_64-apple-darwin.tar.bz2 In case someone wants to confirm my findings. Cheers, Christiaan On Sep 16, 2013, at 2:24 PM, Christiaan Baaij christiaan.ba...@gmail.com javascript:; wrote: Hi, I saw the same issue/crash on my machine using ghc 7.6.3. I just build a perf build of GHC-head with 85a9e2468dc74b9e5ccde0dd61be86219fd323a2 as the latest commit. Now running, I get: 1) cabal install bindings-glfw 2) ghci 3) ghci :m Bindings.GLFW 4) ghci Bindings.GLFW.c'glfwInit 5) ghci 1 And doing: 1.) cabal install GLFW-b 2.) ghci -package GLFW-b 3.) ghci import Graphics.UI.GLFW as GLFW 4.) ghci GLFW.init 5.) ghci True My platform: - OSX 10.8.4 - ghc(i) 7.7.20130915 - cabal 1.18.0.1 (using 1.18.0 of the Cabal library) - xcode cltools 4.6.2 So it seems that the new ghci linking infrastructure fixes things Cheers, Christiaan On Sep 14, 2013, at 9:00 PM, Jan-Philip Loos maxda...@gmail.comjavascript:; wrote: What I do for GLFW is use a dylib, then you don't rely on GHCi's static-ish linker. The only wrinkle is figuring out where you want the dylib. I think homebrew will put one in /usr/local/lib, which works out nicely, but they don't have GLFW 3 yet. Another option is to build the dylib yourself from the GLFW source bundled with the GLFW-b package, then tell cabal where to find it. Hi, for me the problem relocates now to the bindings-glfw package, since the native bindings moved to this package and are wrapped up with glfw-b. My way to the same exception already mentioned by Brian Lewis: 1) cabal install bindings-glfw 2) ghci 3) ghci :m Bindings.GLFW 4) ghci Bindings.GLFW.c'glfwInit 5) ghci terminates with exception: *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSAutoreleasePool init]: unrecognized selector sent to instance 0x7fc443c01b30' Anthony Cowley mentioned to use ghci with GLFW as a dylib, I have no clue how to do this. I built the according glfw version on my own as a dylib and loaded ghci with it explicitly, this didn't help. I guess the compiled bindings-glfw is already statically packed up. How can I get ghci to use the native glfw dylib in combination with bindings-glfw? If I have to compile bindings-glfw with different settings, which settings? I have some oversight over haskell but no really deep knowledge according to bindings and lib-loading of ghci, but I'm willing to learn it ;) My Platform: - OSX 10.8.5 - ghc(i) 7.6.3 - cabal 1.18.0.1 - xcode dev tools 4.6.3 Thanks and Greetings Jan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org javascript:; 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] Haskell Weekly News: Issue 280
Welcome to issue 280 of the HWN, an issue covering crowd-sourced bits of information about Haskell from around the web. This issue covers the week of September 8 to 14, 2013. Quotes of the Week * haasn: edwardk uses things in anger. shachaf uses them with disappointment :( * shachaf: Are you reading Mac Lane now? Saizan: yeah, it's not so bad if you skip the examples Top Reddit Stories * For my 17th birthday, my best friend got me The most obscure programming book I could find as a joke. I know what language I am learning next! Domain: i.imgur.com, Score: 163, Comments: 67 On Reddit: [1] http://goo.gl/0SyN5l Original: [2] http://goo.gl/oqGBzL * pipes-4.0: Simpler types and API Domain: haskellforall.com, Score: 95, Comments: 36 On Reddit: [3] http://goo.gl/ciVnq5 Original: [4] http://goo.gl/g9oq3i * Hackage 2 now available for beta testing -- switchover in a few weeks Domain: beta.hackage.haskell.org, Score: 91, Comments: 17 On Reddit: [5] http://goo.gl/aIhL67 Original: [6] http://goo.gl/zfprr9 * Cartesian Closed Comic #22: Cabal 1.18 Domain: ro-che.info, Score: 90, Comments: 3 On Reddit: [7] http://goo.gl/tVUUFG Original: [8] http://goo.gl/O0BR6c * Parallel and Incremental CRCs by Edward Kmett Domain: fpcomplete.com, Score: 58, Comments: 7 On Reddit: [9] http://goo.gl/YAChJl Original: [10] http://goo.gl/WnMsbY * Conquering Folds by Edward Kmett Domain: fpcomplete.com, Score: 47, Comments: 42 On Reddit: [11] http://goo.gl/reAjgu Original: [12] http://goo.gl/kHsSye * Conal Elliot: From Haskell to hardware via cartesian closed categories Domain: conal.net, Score: 47, Comments: 3 On Reddit: [13] http://goo.gl/VCwp7Y Original: [14] http://goo.gl/NO1sbs * FP Complete to release a personal edition of their online IDE Domain: fpcomplete.com, Score: 39, Comments: 38 On Reddit: [15] http://goo.gl/QOMy5Y Original: [16] http://goo.gl/XBE7zT * Quark : A Web Browser with a Formally Verified Kernel Domain: goto.ucsd.edu, Score: 36, Comments: 6 On Reddit: [17] http://goo.gl/RDZMY0 Original: [18] http://goo.gl/rgBcki * My first Haskell program - FNIStash - a utility for Torchlight 2 using threepenny for the GUI Domain: fluffynukeit.com, Score: 36, Comments: 19 On Reddit: [19] http://goo.gl/cK2N8v Original: [20] http://goo.gl/XOMTgQ * Conal Elliott: Overloading lambda Domain: conal.net, Score: 34, Comments: 4 On Reddit: [21] http://goo.gl/fQTt1P Original: [22] http://goo.gl/oPSQ3R * Cost semantics for STG in modern GHC Domain: blog.ezyang.com, Score: 31, Comments: 5 On Reddit: [23] http://goo.gl/mIQQxm Original: [24] http://goo.gl/5Sa49T * 0install - Python vs. OCaml vs. Haskell Domain: roscidus.com, Score: 31, Comments: 23 On Reddit: [25] http://goo.gl/htCf1x Original: [26] http://goo.gl/zhrVp0 * LogicGrowsOnTrees: a parallel implementation of logic programming using distributed tree exploration Domain: github.com, Score: 31, Comments: 9 On Reddit: [27] http://goo.gl/zp5lou Original: [28] http://goo.gl/5BgYh2 * RSS reader made by Haskell running on mbed platform (RAM size 64kB, using Ajhc Haskell compiler). Domain: youtube.com, Score: 30, Comments: 5 On Reddit: [29] http://goo.gl/n0Gkan Original: [30] http://goo.gl/cwL4vP * Conal Elliott: Optimizing CCCs Domain: conal.net, Score: 30, Comments: 12 On Reddit: [31] http://goo.gl/HVv8dr Original: [32] http://goo.gl/MCn0sO * Snap (and Heist) 0.13 released Domain: snapframework.com, Score: 29, Comments: 7 On Reddit: [33] http://goo.gl/zW5Sdn Original: [34] http://goo.gl/1wSLeJ * ANN: threepenny-gui-0.3 – GUI framework that uses the web browser as a display – now with FRP built-in Domain: apfelmus.nfshost.com, Score: 28, Comments: 8 On Reddit: [35] http://goo.gl/RUDrKD Original: [36] http://goo.gl/WZMeZN Top StackOverflow Questions * In Haskell, where does the range ['a'..] stop? votes: 20, answers: 2 Read on SO: [37] http://goo.gl/Oms7lr * Why were Haskell 98's standard classes made inferior to Haskell 1.3's? votes: 18, answers: 1 Read on SO: [38] http://goo.gl/WxvdL2 * 27 different Bool to Bool values in Haskell votes: 14, answers: 1 Read on SO: [39] http://goo.gl/1PcD1g * How to reconstruct Haskell expression from type votes: 10, answers: 1 Read on SO: [40] http://goo.gl/Qx06kz * Can links to anchors in haddock be labeled? votes: 8, answers: 0 Read on SO: [41] http://goo.gl/5deOMM * How to convert between ByteString and Storable Vector? votes: 7, answers: 1 Read on SO: [42] http://goo.gl/zBVVzI * Why is not GHC optimizing for constants? votes: 7, answers: 2 Read on SO: [43] http://goo.gl/sfo64S * newtype around ST
[Haskell-cafe] ANN Vigilance: Get notified when periodical tasks fail to run successfully
Hey Cafe, Just wanted to announce a project I've been tinkering with for a while finally got to a state where I felt comfortable releasing it. Vigilance is a Dead Man's Switch system that notifies you when periodical tasks that fail to check in when you expected them to. An example of this could be registering the daily backups you do of your servers and have them send emails or send HTTP POST requests if backups ever fail to check in. Vigilance provides an executable for doing check-ins and inspecting your watches as well as a simple REST API if you need something embeddable for existing projects. HackageDB: http://hackage.haskell.org/package/vigilance Github: http://github.com/michaelxavier/vigilance Introductory blog post: http://michaelxavier.net/posts/2013-09-17-Announcing-Vigilance-An-Extensible-Dead-Man-s-Switch-System.html -- Michael Xavier http://www.michaelxavier.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
