- Haskell-Cafe - Haskell.org

Constrain Symbol to contain only alphabetic characters
by Alexander Vieth 28 Sep '15

28 Sep '15

Hi Café, Is it possible to do this? I looked through the source for GHC.TypeLits on hackage but found no leads. Thanks for any help, Alex

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STM implementation
by Nicola Gigante 26 Sep '15

26 Sep '15

Hi all, I’m considering the idea of hacking into the STM implementation, but the source in rts/STM.c seems rather dense. Is there some documentation about the internals or some place to start to understand what’s going on? Thank you, Nicola

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Bologna Haskell Meeting, 2015-10-17 @ 9:30
by m 26 Sep '15

26 Sep '15

Dear all, a Bologna Haskell Meeting will take place on Saturday, October 17 at 9:30. For details see here: https://www.eventbrite.it/e/biglietti-incontro-autunnale-haskell-ita-a-bolo… The page is in Italian and English: the main event is in Italian but many people speak English and we will try to include as many participants as possible. If you would like to give a talk, drop a note to Haskell_ITA(a)googlegroups.com (there is probably still a free slot at the beginning or at the end of the evening). In the same building there will also be an Elixir meeting: https://www.eventbrite.it/e/biglietti-bologna-elixir-erlang-meetup-18440536… (but we have a bigger and better meeting room ...) and participants to a meeting can also lurk the other event. Everybody is welcome! And if you are interested in participating to the event, please buy a ticket on Eventbrite (it is free) just for the meeting that you plan to attend to. Thanks, and see you in Bologna, if you happen to be around. P.S.: if anybody is travelling and needs further information about hotels, travel, etcetera, feel free to contact me directly, I'll be glad to help. -- .*. finelli /V\ (/ \) -------------------------------------------------------------- ( ) Linux: Friends dont let friends use Piccolosoffice ^^-^^ -------------------------------------------------------------- A mother takes twenty years to make a man of her boy, and another woman makes a fool of him in twenty minutes. -- Frost

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Parsing Atom feed link
by fr33domlover 26 Sep '15

26 Sep '15

Hello, I'm using the package 'feed' to parse news feeds and I noticed it fails to parse the item links of many feeds! I investigated and apparently here is why. Many Atom feeds in practice seem to publish their item links like this: <link href="http://....."/> But in the 'feed' package, a link is taken to be an item link only if its relation is alternate, i.e. add an attribute rel="alternate". So for these feeds it returns 'Nothing' for 'getItemLink'. A quick workaround is to go over the links manually of course, which solves the issue locally, but I think it should be solved more generally. Is the problem in 'feed' which recognizes links incorrectly, or do those Atom feeds simply use the wrong way to publish item links? Are they required to use "alternate"? I looked at the examples at https://tools.ietf.org/html/rfc4287 and I just checked Octopress (Ruby) and Ikiwiki (Perl) generated feeds. The RFC's examples have item links without "alernate" (as the only item link provided) and both generators I mentioned create feed item links without "alternate". Should 'feed' be fixed to recognize them? From the RFC: atom:link elements MAY have a "rel" attribute that indicates the link relation type. If the "rel" attribute is not present, the link element MUST be interpreted as if the link relation type is "alternate". --fr33

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ANN: stack-0.1.5.0
by Emanuel Borsboom 25 Sep '15

25 Sep '15

New version released of stack, a build tool. See README <https://github.com/commercialhaskell/stack#how-to-install> for installation and upgrade instructions. Note: the binary tarballs’ contents have changed, and they now enclose their contents in a directory, and include documentation. If you have a script that should only extract the stack executable, use something like tar xzf stack-0.1.5.0-x86_64-osx.tar.gz --strip-components=1 stack-0.1.5.0-x86_64-osx/stack. MinGHC installers <https://github.com/fpco/minghc/releases> have also been updated to include this version of stack (and will continue to be updated for future releases). Major changes: - On Windows, we now use a full MSYS2 installation in place of the previous PortableGit. This gives you access to the pacman package manager for more easily installing libraries. - Support for custom GHC binary distributions #530 <https://github.com/commercialhaskell/stack/issues/530> - ghc-variant option in stack.yaml to specify the variant (also --ghc-variant command-line option) - setup-info in stack.yaml, to specify where to download custom binary distributions (also --ghc-bindist command-line option) - Note: On systems with libgmp4 (aka libgmp.so.3), such as CentOS 6, you may need to re-run stack setup due to the centos6 GHC bindist being treated like a variant - A new --pvp-bounds flag to the sdist and upload commands allows automatic adding of PVP upper and/or lower bounds to your dependencies Other enhancements: - Adapt to upcoming Cabal installed package identifier format change #851 <https://github.com/commercialhaskell/stack/issues/851> - stack setup takes a --stack-setup-yaml argument - --file-watch is more discerning about which files to rebuild for #912 <https://github.com/commercialhaskell/stack/issues/912> - stack path now supports --global-pkg-db and --ghc-package-path - --reconfigure flag #914 <https://github.com/commercialhaskell/stack/issues/914> #946 <https://github.com/commercialhaskell/stack/issues/946> - Cached data is written with a checksum of its structure #889 <https://github.com/commercialhaskell/stack/issues/889> - Fully removed --optimizations flag - Added --cabal-verbose flag - Added --file-watch-poll flag for polling instead of using filesystem events (useful for running tests in a Docker container while modifying code in the host environment. When code is injected into the container via a volume, the container won’t propagate filesystem events). - Give a preemptive error message when -prof is given as a GHC option #1015 <https://github.com/commercialhaskell/stack/issues/1015> - Locking is now optional, and will be turned on by setting the STACK_LOCK environment variable to true #950 <https://github.com/commercialhaskell/stack/issues/950> - Create default stack.yaml with documentation comments and commented out options #226 <https://github.com/commercialhaskell/stack/issues/226> - Out of memory warning if Cabal exits with -9 #947 <https://github.com/commercialhaskell/stack/issues/947> Bug fixes: - Hacky workaround for optparse-applicative issue with stack exec --help #806 <https://github.com/commercialhaskell/stack/issues/806> - Build executables for local extra deps #920 <https://github.com/commercialhaskell/stack/issues/920> - copyFile can’t handle directories #942 <https://github.com/commercialhaskell/stack/pull/942> - Support for spaces in Haddock interface files fpco/minghc#85 <https://github.com/fpco/minghc/issues/85> - Temporarily building against a “shadowing” local package? #992 <https://github.com/commercialhaskell/stack/issues/992> - Fix Setup.exe name for —upgrade-cabal on Windows #1002 <https://github.com/commercialhaskell/stack/issues/1002> - Unlisted dependencies no longer trigger extraneous second build #838 <https://github.com/commercialhaskell/stack/issues/838>

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Munich Haskell Meeting, 2015-09-28 @ 19:30
by Christian Neukirchen 25 Sep '15

25 Sep '15

Dear all, Next week, our monthly Munich Haskell Meeting will take place again on Monday, September 28 at Cafe Puck at 19h30. For details see here: http://chneukirchen.github.io/haskell-munich.de/dates (http://www.haskell-munich.de/ is currently out of order, but will be restored soon!) If you plan to join, please add yourself to this dudle so we can reserve enough seats! It is OK to add yourself to the dudle anonymously or pseudonymously. https://dudle.inf.tu-dresden.de/haskell-munich-sep-2015/ Everybody is welcome! cu, -- Christian Neukirchen <chneukirchen(a)gmail.com> http://chneukirchen.org

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Simply and easy graphical toolkit?
by Christopher Howard 24 Sep '15

24 Sep '15

Hi. What would be the simplest and easiest Haskell graphical toolkit to use? I remember a few years ago I tried Gloss and was really happy with it, but I also wanted to be able to have a few buttons and text fields on the screen for user input, without having to build them from scratch. -- http://justonemoremathproblem.com/

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ANN: The Herbie GHC Plugin
by Mike Izbicki 24 Sep '15

24 Sep '15

80% of packages in stackage that contain floating point expressions have numerically unstable expressions. The Herbie GHC plugin automatically makes these expressions numerically stable. You can find the project on github at: https://github.com/mikeizbicki/HerbiePlugin

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ANN: CfN for new Haskell Prime language committee
by Herbert Valerio Riedel 23 Sep '15

23 Sep '15

Dear Haskell Community, In short, it's time to assemble a new Haskell Prime language committee. Please refer to the CfN at https://mail.haskell.org/pipermail/haskell-prime/2015-September/003936.html for more details. Cheers, hvr -- PGP fingerprint: 427C B69A AC9D 00F2 A43C AF1C BA3C BA3F FE22 B574

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ANN: FunGEn-1.0 - easy-to-install cross-platform game engine
by Simon Michael 22 Sep '15

22 Sep '15

I'm pleased to announce the release of FunGEn 1.0 ! What is it ? FunGEn (Functional Game Engine) is the oldest game engine in Haskell. It was created by Andre Furtado in 2002, has never been used since, and yet it is arguably still the easiest and most practical way to make a video game using Haskell. It is BSD-licensed, installs easily on unix, mac and windows, does not use FRP, and comes with two playable example games. What does it do ? Here's Andre's original feature list: - Initialization, updating, removing, rendering and grouping routines for game objects; - Definition of a game background (or map), including texture-based maps and tile maps; - Reading and intepretation of the player's keyboard input; - Collision detection; - Time-based functions and pre-defined game actions; - Loading and displaying of 24-bit bitmap files; - Some debugging and game performance evaluation facilities; - Sound support (actually for windows platforms only... :-[ ) What's new in 1.0 ? - supports GHC 7.10 - supports stack - the repo (and project) has moved to the haskell-game organization on Github How to install $ cabal update $ cabal install FunGEn # ensure ~/.cabal/bin or windows equiv. is in your PATH or $ git clone https://github.com/haskell-game/fungen $ cd fungen $ stack install How to run the examples $ fungen-hello $ fungen-pong $ fungen-worms More info http://hackage.haskell.org/package/FunGEn https://github.com/haskell-game/fungen http://joyful.com/fungen - old home page Why ? I think FunGEn still has some value, for building games and also as an example of how to structure games in haskell. I don't have time to do much with it, so I've moved it to the haskell-game organization, where all org members now have push access. I'd like it to be as open as possible to contributors, and am seeking a new or co- maintainer. Best, -Simon (sm on #haskell-game)

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