Re: [Haskell-cafe] Again, version conflicting problem with cabal-install
OK. I found cabal-src tool, which solved this perfect. On Wed, Jun 20, 2012 at 9:22 AM, Magicloud Magiclouds magicloud.magiclo...@gmail.com wrote: Hi, The names here were just placeholder. And I just found out the reason. Hackage magicloud is local (not from hackage.haskell.org), there is no its information in cabal INDEX (I assumed so). But this raised another question, how to reference a local hackage in .cabal. So the solver could use the dependencies originally defined but not the binary compiled (which dependencies are fixed)? On Tue, Jun 19, 2012 at 5:50 PM, Andres Löh andres.l...@googlemail.com wrote: Hi. Hackage A depends on magicloud (any) and container (0.4.0.0), and hackage magicloud depends on container (any). Now I've installed magicloud, using container 0.5.0.0. Then I failed to install A, with any solver. So the solvers are using the status that is installed, not the definitions from original hackages? Could you please provide me with something I can reproduce? I'm not sure what you mean by A or magicloud. Are you saying they have no further dependencies except for the one on container? If you could just state which concrete packages have caused the problem, it'd probably be easier. The trace output of the modular solver with -v3 would also help (send it to me personally if it's too long). Thanks. Andres -- 竹密岂妨流水过 山高哪阻野云飞 And for G+, please use magiclouds#gmail.com. -- 竹密岂妨流水过 山高哪阻野云飞 And for G+, please use magiclouds#gmail.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [Haskell] [ANN] GenCheck - a generalized property-based testing framework
On Tue, 19 Jun 2012, Jacques Carette wrote: Its main novel features are: * introduces a number of /testing strategies/ and /strategy combinators/ * introduces a variety of test execution methods * guarantees uniform sampling (at each rank) for the random strategy * guarantees both uniqueness and coverage of all structures for the exhaustive strategy * introduces an /extreme/ strategy for testing unbalanced structures * also introduces a /uniform/ strategy which does uniform sampling along an enumeration * allows different strategies to be mixed; for example one can exhaustively test all binary trees up to a certain size, filled with random integers. * complete separation between properties, generators, testing strategies and test execution methods This sounds very interesting to me since I had a lot of trouble with changed test case distributions when switching from QuickCheck-1 to QuickCheck-2. It was mainly that tested numbers became much bigger in QuickCheck-2 and if I used the numbers as size of lists, then tests could not be run in reasonable time anymore. Thus I think more control over test-case generation is necessary. QuickCheck is Haskell-98 and thus is very portable. I see that GenCheck needs some more extensions - type families, multi-parameter type classes, what else? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Problem with plugins
I really have no idea. I am the new plugins maintainer -- but so far that mostly means I am willing to apply darcs patches and uploading things to hackage. I have not had a chance to really dig into plugins. I will now make some wild guesses. 1. does it matter if you compile with -O2 vs -O0 ? 2. do those .o files actually exist? 3. Are there perhaps .o and .hi files in your project directory that were compiled with GHC 7.0 but now you are trying to load them with = 7.0? - jeremy On Tue, Jun 19, 2012 at 10:30 AM, Timo von Holtz timo.v.ho...@googlemail.com wrote: Hi, I'm currently working on extending the hascat Server. My problem is, that for whatever odd reason it will only work on GHC 7.0 or alternatively if I execute it with runghc or in ghci. If I compile it with GHC=7.0 and execute it, then I get this: $ ~/.cabal/bin/hascat config.xml Installing Root at / hascat: /home/tvh/.cabal/lib/plugins-1.5.2.1/ghc-7.4.1/HSplugins-1.5.2.1.o: unknown symbol `ghczm7zi4zi1_ErrUtils_zdsinsertzugo3_info' hascat: unloadObj: can't find `/usr/lib/ghc/binary-0.5.1.0/HSbinary-0.5.1.0.o' to unload user error (unloadObj: failed) Installing Hascat Server Info at /ServerInfo/ hascat: /home/tvh/.cabal/lib/hascat-system-0.2/ghc-7.4.1/HShascat-system-0.2.o: unknown symbol `base_DataziMaybe_Nothing_closure' hascat: unloadObj: can't find `/usr/lib/ghc/Cabal-1.14.0/HSCabal-1.14.0.o' to unload user error (unloadObj: failed) Installing Hascat Application Manager at /Manager/ hascat: /home/tvh/.cabal/lib/hascat-system-0.2/ghc-7.4.1/HShascat-system-0.2.o: unknown symbol `base_DataziMaybe_Nothing_closure' hascat: unloadObj: can't find `/usr/lib/ghc/Cabal-1.14.0/HSCabal-1.14.0.o' to unload user error (unloadObj: failed) Installing Hascat Application Deployer at /Deployer/ hascat: /usr/lib/haskell-packages/ghc/lib/zlib-0.5.3.3/ghc-7.4.1/HSzlib-0.5.3.3.o: unknown symbol `base_GHCziForeignPtr_ForeignPtr_con_info' hascat: unloadObj: can't find `/usr/lib/ghc/Cabal-1.14.0/HSCabal-1.14.0.o' to unload user error (unloadObj: failed) Waiting for connections on port 8012 Is there a way to make this work? Greetings Timo ___ 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] Problem with plugins
I compile the files dynamically, so the compiler version is out of the question. I already tested -O0. In the modules I dynamically load, I import some of the modules the main program also uses. I can reproduce the exact same error with this simple example: Main.hs: module Main (main, add) where import System.Plugins add = (+1) main :: IO () main = do putStrLn Loading makeAll Plug.hs [] mv - load_ Plug.o [.] thing putStrLn Loaded case mv of LoadFailure msgs - putStrLn fail print msgs LoadSuccess _ v - putStrLn success print (v::Integer) Plug.hs: module Plug (thing) where import Main thing :: Integer thing = add 1234000 - timo 2012/6/20 Jeremy Shaw jer...@n-heptane.com I really have no idea. I am the new plugins maintainer -- but so far that mostly means I am willing to apply darcs patches and uploading things to hackage. I have not had a chance to really dig into plugins. I will now make some wild guesses. 1. does it matter if you compile with -O2 vs -O0 ? 2. do those .o files actually exist? 3. Are there perhaps .o and .hi files in your project directory that were compiled with GHC 7.0 but now you are trying to load them with = 7.0? - jeremy On Tue, Jun 19, 2012 at 10:30 AM, Timo von Holtz timo.v.ho...@googlemail.com wrote: Hi, I'm currently working on extending the hascat Server. My problem is, that for whatever odd reason it will only work on GHC 7.0 or alternatively if I execute it with runghc or in ghci. If I compile it with GHC=7.0 and execute it, then I get this: $ ~/.cabal/bin/hascat config.xml Installing Root at / hascat: /home/tvh/.cabal/lib/plugins-1.5.2.1/ghc-7.4.1/HSplugins-1.5.2.1.o: unknown symbol `ghczm7zi4zi1_ErrUtils_zdsinsertzugo3_info' hascat: unloadObj: can't find `/usr/lib/ghc/binary-0.5.1.0/HSbinary-0.5.1.0.o' to unload user error (unloadObj: failed) Installing Hascat Server Info at /ServerInfo/ hascat: /home/tvh/.cabal/lib/hascat-system-0.2/ghc-7.4.1/HShascat-system-0.2.o: unknown symbol `base_DataziMaybe_Nothing_closure' hascat: unloadObj: can't find `/usr/lib/ghc/Cabal-1.14.0/HSCabal-1.14.0.o' to unload user error (unloadObj: failed) Installing Hascat Application Manager at /Manager/ hascat: /home/tvh/.cabal/lib/hascat-system-0.2/ghc-7.4.1/HShascat-system-0.2.o: unknown symbol `base_DataziMaybe_Nothing_closure' hascat: unloadObj: can't find `/usr/lib/ghc/Cabal-1.14.0/HSCabal-1.14.0.o' to unload user error (unloadObj: failed) Installing Hascat Application Deployer at /Deployer/ hascat: /usr/lib/haskell-packages/ghc/lib/zlib-0.5.3.3/ghc-7.4.1/HSzlib-0.5.3.3.o: unknown symbol `base_GHCziForeignPtr_ForeignPtr_con_info' hascat: unloadObj: can't find `/usr/lib/ghc/Cabal-1.14.0/HSCabal-1.14.0.o' to unload user error (unloadObj: failed) Waiting for connections on port 8012 Is there a way to make this work? Greetings Timo ___ 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] Problem with plugins
My example was somewhat wrong, since it only works with runghc = 7.0 and not 7. Here a better example which has exactly the same issues as my code. Main.hs: module Main where import Main1 main = main1 Main1.hs: module Main1 (main1, add) where import System.Plugins add = (+1) main1 :: IO () main1 = do putStrLn Loading makeAll Plug.hs [] mv - load_ Plug.o [.] thing putStrLn Loaded case mv of LoadFailure msgs - putStrLn fail print msgs LoadSuccess _ v - putStrLn success print (v::Integer) Plug.hs: module Plug (thing) where import Main1 thing :: Integer thing = add 1234000 - timo 2012/6/20 Timo von Holtz timo.v.ho...@googlemail.com: I compile the files dynamically, so the compiler version is out of the question. I already tested -O0. In the modules I dynamically load, I import some of the modules the main program also uses. I can reproduce the exact same error with this simple example: Main.hs: module Main (main, add) where import System.Plugins add = (+1) main :: IO () main = do putStrLn Loading makeAll Plug.hs [] mv - load_ Plug.o [.] thing putStrLn Loaded case mv of LoadFailure msgs - putStrLn fail print msgs LoadSuccess _ v - putStrLn success print (v::Integer) Plug.hs: module Plug (thing) where import Main thing :: Integer thing = add 1234000 - timo 2012/6/20 Jeremy Shaw jer...@n-heptane.com I really have no idea. I am the new plugins maintainer -- but so far that mostly means I am willing to apply darcs patches and uploading things to hackage. I have not had a chance to really dig into plugins. I will now make some wild guesses. 1. does it matter if you compile with -O2 vs -O0 ? 2. do those .o files actually exist? 3. Are there perhaps .o and .hi files in your project directory that were compiled with GHC 7.0 but now you are trying to load them with = 7.0? - jeremy On Tue, Jun 19, 2012 at 10:30 AM, Timo von Holtz timo.v.ho...@googlemail.com wrote: Hi, I'm currently working on extending the hascat Server. My problem is, that for whatever odd reason it will only work on GHC 7.0 or alternatively if I execute it with runghc or in ghci. If I compile it with GHC=7.0 and execute it, then I get this: $ ~/.cabal/bin/hascat config.xml Installing Root at / hascat: /home/tvh/.cabal/lib/plugins-1.5.2.1/ghc-7.4.1/HSplugins-1.5.2.1.o: unknown symbol `ghczm7zi4zi1_ErrUtils_zdsinsertzugo3_info' hascat: unloadObj: can't find `/usr/lib/ghc/binary-0.5.1.0/HSbinary-0.5.1.0.o' to unload user error (unloadObj: failed) Installing Hascat Server Info at /ServerInfo/ hascat: /home/tvh/.cabal/lib/hascat-system-0.2/ghc-7.4.1/HShascat-system-0.2.o: unknown symbol `base_DataziMaybe_Nothing_closure' hascat: unloadObj: can't find `/usr/lib/ghc/Cabal-1.14.0/HSCabal-1.14.0.o' to unload user error (unloadObj: failed) Installing Hascat Application Manager at /Manager/ hascat: /home/tvh/.cabal/lib/hascat-system-0.2/ghc-7.4.1/HShascat-system-0.2.o: unknown symbol `base_DataziMaybe_Nothing_closure' hascat: unloadObj: can't find `/usr/lib/ghc/Cabal-1.14.0/HSCabal-1.14.0.o' to unload user error (unloadObj: failed) Installing Hascat Application Deployer at /Deployer/ hascat: /usr/lib/haskell-packages/ghc/lib/zlib-0.5.3.3/ghc-7.4.1/HSzlib-0.5.3.3.o: unknown symbol `base_GHCziForeignPtr_ForeignPtr_con_info' hascat: unloadObj: can't find `/usr/lib/ghc/Cabal-1.14.0/HSCabal-1.14.0.o' to unload user error (unloadObj: failed) Waiting for connections on port 8012 Is there a way to make this work? Greetings Timo ___ 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] Hackage 2 maintainership
Krzysztof Skrzętnicki gte...@gmail.com writes: Hi, Are there any news how things are going? Things have been pretty stagnant yet again. I was more than a bit over-optimistic concerning the amount of time I'd have available to put into this project. Moreover, the tasks required to get Hackage into a usable state weren't nearly as clear as I originally thought. Unfortunately, those who have historically been very active in Hackage development and would have been responsible for much of the recent work in advancing Hackage 2 to where it is now have other demands on their time. My understanding is there is a fair amount of half-completed code floating around. What remains there to be done to get us to Hackage 2? I found this list of tickets: https://github.com/haskell/cabal/issues?labels=hackage2page=1state=open Is there anything more to be done? This list is definitely a start. One of the issues that was also realized is the size of the server's memory footprint. Unfortunately acid-state's requirement that all data either be in memory or have no ACID guarantees was found to be a bit of a limitation. If I recall correctly some folks were playing around with restructuring the data structures a bit to reduce memory usage. I really don't know what happened to these efforts. On the other hand, it seems that the test server is still ticking away at http://hackage.factisresearch.com/ with an up-to-date package index, so things are looking alright on that front. At this point, it seems that we are in a situation yet again where someone just needs to start applying gentle pressure and figure out where we stand. I'm afraid especially now I simply don't have time to take on this project in any serious capacity. Perhaps one way forward would be to propose the project again as a GSoC project next year. That being said, there is no guarantee that someone would step up to finish it. Just my two cents. Cheers, - Ben ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [Haskell] [ANN] GenCheck - a generalized property-based testing framework
On 20/06/2012 6:56 AM, Henning Thielemann wrote: QuickCheck is Haskell-98 and thus is very portable. I see that GenCheck needs some more extensions - type families, multi-parameter type classes, what else? FlexibleContexts and FlexibleInstances. However, I am fairly sure that the multi-parameter type classes are not in fact needed. Certainly a branch of the current implementation could easily be done that removes these without harming the functionality currently implemented, although it might harm some of the extensibility. And I think most of the uses of FlexibleContexts/Instances are tied to these MPTCs. The one use of type families is to implement a view or, if you prefer, the 'get' part of a lens. With type families, this is extremely elegant. If portability is really important, this too could probably be branched into an implementation that does this otherwise. I am actively working on refactoring the LabelledPartition MPTC into simpler pieces, but you'll have to wait until gencheck-0.2 for that. Jacques ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] [Word8] - FilePath using ghc's file system encoding
I found myself writing the code below today, and thought I'd write to see if
there's a better way, perhaps one that doesn't use unsafePerformIO.
A sample use case for this is a program that reads a FilePath from a Handle,
and then operates on that file on disk. GHC uses a special encoding for
FilePaths that cleanly roundtrips invalid utf8, but for that to work,
the FilePath must be read using that encoding too. Neglecting to do that
would result in a program that worked for most filenames, but failed on edge
case non-utf8 encoded filenames.
Another way to deal with this problem is to first hSetEncoding using
GHC.IO.Encoding.getFileSystemEncoding, and then read from the Handle using
hGetLine, which applies the encoding to the data it reads. However, in this
case I needed to use ByteString to read from the Handle, and so needed a way to
convert from a ByteString to a FilePath. (Using RawFilePath would be another
approach, but reworking my program to use it isn't practical.)
Anyway, it seems there should be a pure way to encode a string with
GHC's filesystem encoding.
-
import qualified GHC.Foreign as GHC
import qualified GHC.IO.Encoding as Encoding
import System.IO.Unsafe
import Data.Bits.Utils -- from MissingH
{- Converts a [Word8] to a FilePath, encoding using the filesystem encoding.
-
- w82c produces a String, which may contain Chars that are invalid
- unicode. From there, this is really a simple matter of applying the
- file system encoding, only complicated by GHC's interface to doing so.
-}
{-# NOINLINE encodeW8 #-}
encodeW8 :: [Word8] - FilePath
encodeW8 w8 = unsafePerformIO $ do
enc - Encoding.getFileSystemEncoding
GHC.withCString Encoding.char8 (w82s w8) (GHC.peekCString enc)
--
see shy jo
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[Haskell-cafe] relocation R_X86_64_PC32 against undefined symbol
Just for the record: I compiled with GHC and got the linker error: /usr/bin/ld: dist/build/.../Module.dyn_o: relocation R_X86_64_PC32 against undefined symbol `..._xyz1_closure' can not be used when making a shared object; recompile with -fPIC Problem was that I forgot to declare Module in the Cabal description. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [Haskell] JustHub 'Sherkin' Release
[Sorry for the delay -- I missed this reply until prompted.] Very nice, this looks quite straightforward. I wonder about two things: - Is it possible to pass configure-time flags to those libraries? For example, I would like to build haskeline with -fterminfo. Can Hub do this? - How do you handle packages that depend on system libraries? hsdns, for example, requires the adns library to build. Does Hub know about this? Well observed! There is currently no provision for getting special arguments passed to cabal install when rebuilding the packages -- a weakness that should be addressed. Chris ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] The use of continuation monad in C++
I published a blog for C++ programmers about the advantages of using the continuation monad in dealing with asynchronous API, concurrency, and parallelism. I explained the concepts in Haskell and the translated them into C++. http://fpcomplete.com/asynchronous-api-in-c-and-the-continuation-monad/ -- [:Bartosz:] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [Haskell] JustHub 'Sherkin' Release
Hi Chris, I'm also wondering about this issue: - How do you handle packages that depend on system libraries? hsdns, for example, requires the adns library to build. Does Hub know about this? Does Hub know about system-level libraries that Haskell packages need to build, like Gtk, ADNS, Avahi, etc.? Take care, Peter ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANNOUNCE : Leksah 0.12.1.2 (fixes some metadata issues)
Hi Hamish, On 19 June 2012 22:47, Hamish Mackenzie hamish.k.macken...@googlemail.com wrote: This release has an important bug fix for the metadata download. When metadata was downloaded using libcurl it was not treated as binary data. If you used one of our binary installers or if you built Leksah with the -flibcurl flag then it is likely you have bad metadata files. I just tried (again) to install Leksah. I was wondering if you could point out where I go wrong. I'm on a fully up-to-date Gentoo Linux (kernel 3.4.3, 64 bit) box. I ran the following commands (as described, more or less, on http://leksah.org/download.html): hilco@centaur ~ ~$ rm -rf .cabal/ hilco@centaur ~ ~$ cabal update Downloading the latest package list from hackage.haskell.org hilco@centaur ~ ~$ cabal install gtk2hs-buildtools Resolving dependencies... Downloading gtk2hs-buildtools-0.12.3.1... Configuring gtk2hs-buildtools-0.12.3.1... Building gtk2hs-buildtools-0.12.3.1... ... lots of output ... Linking dist/build/gtk2hsC2hs/gtk2hsC2hs ... Installing executable(s) in /home/hilco/.cabal/bin hilco@centaur ~ ~$ cabal install leksah Resolving dependencies... In order, the following would be installed: attoparsec-0.10.2.0 (reinstall) changes: text-0.11.2.2 added binary-shared-0.8.2 (new version) cairo-0.12.3.1 (new package) enumerator-0.4.19 (reinstall) changes: text-0.11.2.2 added, transformers-0.2.2.0 - 0.3.0.0 attoparsec-enumerator-0.3 (reinstall) changes: text-0.11.2.2 added glib-0.12.3.1 (new package) gio-0.12.3 (new package) network-2.3.0.14 (reinstall) changes: parsec-3.1.2 - 3.1.3 hslogger-1.1.5 (reinstall) changes: mtl-2.0.1.0 - 2.1.1 pango-0.12.3 (new package) gtk-0.12.3.1 (new package) gtksourceview2-0.12.3.1 (new package) ltk-0.12.1.0 (new package) leksah-server-0.12.1.2 (new package) regex-base-0.93.2 (reinstall) changes: mtl-2.0.1.0 - 2.1.1 regex-tdfa-1.1.8 (reinstall) changes: mtl-2.0.1.0 - 2.1.1, parsec-3.1.2 - 3.1.3 leksah-0.12.1.2 (new package) cabal: The following packages are likely to be broken by the reinstalls: regex-posix-0.95.1 regex-compat-0.95.1 Use --force-reinstalls if you want to install anyway. hilco@centaur ~ ~$ cabal install leksah --force-reinstalls Resolving dependencies... Warning: The following packages are likely to be broken by the reinstalls: regex-posix-0.95.1 regex-compat-0.95.1 Continuing even though the plan contains dangerous reinstalls. ... lots of output ... cabal: Error: some packages failed to install: cairo-0.12.3.1 failed during the configure step. The exception was: ExitFailure 1 gio-0.12.3 depends on glib-0.12.3.1 which failed to install. glib-0.12.3.1 failed during the configure step. The exception was: ExitFailure 1 gtk-0.12.3.1 depends on glib-0.12.3.1 which failed to install. gtksourceview2-0.12.3.1 depends on glib-0.12.3.1 which failed to install. leksah-0.12.1.2 depends on glib-0.12.3.1 which failed to install. leksah-server-0.12.1.2 depends on glib-0.12.3.1 which failed to install. ltk-0.12.1.0 depends on glib-0.12.3.1 which failed to install. pango-0.12.3 depends on glib-0.12.3.1 which failed to install. Any ideas? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANNOUNCE : Leksah 0.12.1.2 (fixes some metadata issues)
On 12-06-20 07:59 PM, Hilco Wijbenga wrote: hilco@centaur ~ ~$ rm -rf .cabal/ I am not sure why you start with this. If you do this for a clean start, see my http://www.vex.net/~trebla/haskell/sicp.xhtml#remove for why it is not a clean start. If you do this for some other purpose, nevermind. ... lots of output ... I think that is the informative part. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANNOUNCE : Leksah 0.12.1.2 (fixes some metadata issues)
On 20 June 2012 18:22, Oliver Batchelor saul...@gmail.com wrote: Check the error given by cairo. cabal install cairo-0.12.3.1 Well, it wasn't cairo that was the problem but ... You probably need to put the .cabal/bin in your PATH, so that the tools such as c2hs can run. ... indeed, adding .cabal/bin to my PATH allowed the install to finish successfully. Why doesn't cabal abort when a package fails to install? Why doesn't it die if .cabal/bin isn't on the PATH? (Surely, that's easy to test for?) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Haskell Weekly News: Issue 232
Welcome to issue 232 of the HWN, an issue covering crowd-sourced bits of information about Haskell from around the web. This issue covers the week of June 10 to 16, 2012. Quotes of the Week * irene-knapp: ewtoombs: the universe is already an interactive quantum physics simulator * Philipp: While in Python every problem can be solved with a big enough Hashtable, in Haskell, every problem can be solved with an additional type parameter. * kulin: man, i am loving this existential quantification, i feel like now i will use it incorrectly to solve every problem for sure * mekeor: xmonad is awesome (ignore the ambiguity, please) Top Reddit Stories * Waldo - the Haskell powered codebase behind xkcd’s Umwelt comic Domain: self.haskell, Score: 75, Comments: 16 On Reddit: [1] http://goo.gl/M2fGv Original: [2] http://goo.gl/M2fGv * “ARM is now a fully supported target platform for GHC, complete with GHCi support” Domain: haskell.org, Score: 60, Comments: 17 On Reddit: [3] http://goo.gl/O0XK3 Original: [4] http://goo.gl/0Fajp * 3D Mandelbrot in OpenGL from imperative to functional style. Domain: yannesposito.com, Score: 36, Comments: 8 On Reddit: [5] http://goo.gl/5MKK1 Original: [6] http://goo.gl/nzpvl * ANN: clckwrks - a Haskell blogging and CMS framework Domain: groups.google.com, Score: 35, Comments: 21 On Reddit: [7] http://goo.gl/ROrHt Original: [8] http://goo.gl/WneBw * web server C10k benchmark: snap vs. erlang, go, node.js, java Domain: github.com, Score: 35, Comments: 5 On Reddit: [9] http://goo.gl/r1Q1j Original: [10] http://goo.gl/eFlTm * GADTs Domain: haskellforall.com, Score: 33, Comments: 74 On Reddit: [11] http://goo.gl/B41Ef Original: [12] http://goo.gl/rcL6I * Announcing Elm 0.2: Haskell integration (Yesod, HAppStack, and Snap), better error messages, larger examples, and more. Domain: self.haskell, Score: 30, Comments: 8 On Reddit: [13] http://goo.gl/ENBPH Original: [14] http://goo.gl/ENBPH * command line options using applicative without Template Haskell Domain: github.com, Score: 28, Comments: 13 On Reddit: [15] http://goo.gl/zqKGw Original: [16] http://goo.gl/eVSAb * Haskell and Yesod - Book on writing web applications in Haskell Domain: shop.oreilly.com, Score: 28, Comments: 5 On Reddit: [17] http://goo.gl/0RdvE Original: [18] http://goo.gl/9qCEu Top StackOverflow Questions * Tying the Knot with a State monad votes: 33, answers: 3 Read on SO: [19] http://goo.gl/cMcRf * Lazy evaluation of terms in an infinite list in Haskell votes: 32, answers: 4 Read on SO: [20] http://goo.gl/IyRJ1 * What is going on with the types in this ghci session? votes: 17, answers: 1 Read on SO: [21] http://goo.gl/3RVnN * the seq function and strictness votes: 14, answers: 2 Read on SO: [22] http://goo.gl/f8u9G * Is it possible to “hide” language extensions? votes: 11, answers: 2 Read on SO: [23] http://goo.gl/q4JQx * Rebinding do notation for indexed monads votes: 11, answers: 1 Read on SO: [24] http://goo.gl/Z4lnx * Haskell: “how much” of a type should functions receive? and avoiding complete “reconstruction” votes: 9, answers: 1 Read on SO: [25] http://goo.gl/2FFHu * Intelligent purely functional sets votes: 8, answers: 1 Read on SO: [26] http://goo.gl/I7Tzb * Is there a better way to express the absolute error function in point-free notation? votes: 8, answers: 2 Read on SO: [27] http://goo.gl/FFFek * GADTs vs. MultiParamTypeClasses votes: 7, answers: 2 Read on SO: [28] http://goo.gl/3DYKI Until next time, Daniel Santa Cruz References 1. http://www.reddit.com/r/haskell/comments/uved7/waldo_the_haskell_powered_codebase_behind_xkcds/ 2. http://www.reddit.com/r/haskell/comments/uved7/waldo_the_haskell_powered_codebase_behind_xkcds/ 3. http://www.haskell.org/pipermail/haskell-cafe/2012-June/101704.html 4. http://www.reddit.com/r/haskell/comments/uv07c/arm_is_now_a_fully_supported_target_platform_for/ 5. http://yannesposito.com/Scratch/en/blog/Haskell-OpenGL-Mandelbrot/ 6. http://www.reddit.com/r/haskell/comments/v4pzk/3d_mandelbrot_in_opengl_from_imperative_to/ 7. https://groups.google.com/forum/#!msg/clckwrks/58AwDSRRGoI/prrMP6fhtqMJ 8. http://www.reddit.com/r/haskell/comments/uyr0y/ann_clckwrks_a_haskell_blogging_and_cms_framework/ 9. https://github.com/ericmoritz/wsdemo/blob/results-v1/results.md 10. http://www.reddit.com/r/haskell/comments/v595l/web_server_c10k_benchmark_snap_vs_erlang_go/ 11. http://www.haskellforall.com/2012/06/gadts.html 12. http://www.reddit.com/r/haskell/comments/v5ewa/gadts/ 13.
Re: [Haskell-cafe] ANNOUNCE : Leksah 0.12.1.2 (fixes some metadata issues)
On 20 June 2012 18:32, Albert Y. C. Lai tre...@vex.net wrote: On 12-06-20 07:59 PM, Hilco Wijbenga wrote: hilco@centaur ~ ~$ rm -rf .cabal/ I am not sure why you start with this. If you do this for a clean start, see my http://www.vex.net/~trebla/haskell/sicp.xhtml#remove for why it is not a clean start. :-) Thank you for pointing that out. My purpose was indeed to start over. I've also removed .ghc. ... lots of output ... I think that is the informative part. Yes, I suppose so. :-) In my feeble defence: initially there were no errors. It wasn't until I tried --force-reinstalls that there was an error reported (gtk2hsC2hs was not able to run). Even this error, however, was well hidden. No different font, no different colour, no ASCII art drawing attention to it, nothing. So I missed it the first two times. If I had noticed it I would have known to include .cabal/bin in my PATH (it's in the error message). Cabal doesn't seem to believe in fail early, fail loudly? :-) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [Haskell] ANNOUNCE: set-monad
Hi George,
I didn't have access to my computer over the weekend, so I apologize for
not actually running the examples I provided. I was simply projecting what
I thought could reasonably be assumed about the behavior of a Set.
Data.Set.Monad's departure from those assumptions is a double-edged sword,
and so I'd just like to clarify a couple things.
Regarding antisymmetry, if I also define
instance Ord Foo where
(==) = (==) `on` a
then would that count as satisfying the law?
In any event, I find it an amusing coincidence that Data.Set.Monoid does
essentially the same thing as Foo: it retains some extra information, and
provides an Eq instance that asserts equality modulo dropping the extra
information.
So I have a question and a concern. Loading this file into ghci:
hpaste.org/70245
ghci foo1 == foosTransform1
True
ghci foo2 == foosTransform2
False
given x == y, where x and y are Sets, we cannot guarantee that fmap f x ==
fmap f y, due to the extra information retained for the sake of obeying
functor laws.
My question is this: how *does* the library manage to obey functor laws?
My concern is this: the aforementioned behavior should be clearly
documented in the haddocks. Presumably, people will not know about the
extra information being retained. The following, out of context (where most
debugging happens), could be quite confusing:
ghci foosTransform1
fromList [Foo {a = 1, b = 4}]
ghci fmap restoreA foosTransform1
fromList [Foo {a = 1, b = 1},Foo {a = 2, b = 2},Foo {a = 3, b = 3},Foo {a =
4, b = 4}]
The data seems to pop out of nowhere. Even if Ord instances like the one
for Foo shouldn't exist, they almost certainly will anyways, because the
Haskell type system doesn't prevent them. Users of the library should be
informed accordingly.
Dan Burton
801-513-1596
On Mon, Jun 18, 2012 at 2:40 PM, George Giorgidze giorgi...@gmail.comwrote:
Hi Dan,
Thanks for your feedback and your question regarding the functor laws.
Please try your example in GHCi and/or evaluate it by hand. The
library does not violate the functor laws.
I committed quick check properties for functor laws, as well as, laws
for other type classes to the repo. You can give it a try. It is also
possible, with a little bit of effort, to prove those properties by
hand.
Speaking of laws, BTW, your contrived Ord instance violates one of the
Ord laws. The documentation for Ord says that: The Ord class is used
for totally ordered datatypes. Your definition violates the
antisymmetry law [1]:
If a = b and b = a then a == b
by reporting two elements that are not equal as equal.
Cheers, George
[1] http://en.wikipedia.org/wiki/Totally_ordered
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