May 2010 - Haskell - Haskell.org

ANNOUNCE: hdaemonize 0.4
by Frederick Ross 27 May '10

27 May '10

I am pleased to announce the release of hdaemonize 0.4. hdaemonize is a library to handle the details of writing daemons for unix systems. Changes from 0.3 to 0.4: * I have taken over as maintainer from Anton Tayanovskyy. Many thanks to Anton for getting the library started. * Added a field to the CreateDaemon type to specify actions to run before dropping privileges, for example, binding trusted ports. The action has type IO a. Immediately after running it, the program drops privileges, then runs the main daemon routine with the output of the action as its argument. Changes from 0.2 to 0.3 (since I think it didn't get an announcement): * Big API change. In analogy with several other Haskell interfaces, there is now a datatype CreateDaemon which specifies details such as the user to switch to after dropping privileges, the name to run, and arguments to syslog. I am using the library in a couple of daemons, which have driven all the API changes in the last two versions. It is stable enough for general use. There is Haddock documentation, but I would love comments on where it is unclear or ambiguous. -- Frederick Ross Bioinformatics and Biostatistics Core Facility Life Sciences, EPFL http://bbcf.epfl.ch/ +41 21 693 14 39

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Re: [Haskell-cafe] Work on Video Games in Haskell
by David Virebayre 27 May '10

27 May '10

On Wed, May 26, 2010 at 9:23 AM, Lyndon Maydwell <maydwell(a)gmail.com> wrote: > As a side note, how is this project getting around the language > restrictions apple put in the developer license agreement? >From the project page : This version uses Apple's official iPhone SDK as its back end compiler. David.

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How to implement A-lists and P-lists in Haskell (cont.)
by Tom Jordan 26 May '10

26 May '10

Sorry that I couldn't respond to the previous thread.. I'm using Gmail and not an email client so I couldn't use the reply button. I'll try to resolve this issue soon ! Thanks Phillip for responding so quickly, I tried Data.Map first and ran into the issue you mentioned.. I've found a way to get around it, but it's ugly and verbose.. Instead, I'm wondering if there is a way to use the constructors for the "Val" types below, in place of the keys such as: data Val = Root Root | Oct Oct | Mode Mode deriving (Show, Eq, Ord) And matching against the constructors, instead of resorting to this: import IO import qualified Data.Map as Map type Root = String type Oct = Integer type Mode = Integer data Key = Root | Oct | Mode deriving (Show, Eq, Ord) data Val = Root_v Root | Oct_v Oct | Mode_v Mode deriving (Show, Eq, Ord) test = Map.insert Oct (Oct_v 3) . Map.insert Mode (Mode_v 0) . Map.insert Root (Root_v "2") $ Map.empty main = print test -- ----> fromList [(Root,Root_v "2"),(Oct,Oct_v 3),(Mode,Mode_v 0)] Many Thanks, Tom

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Re: [Haskell] Re: [Haskell-cafe] Work on Video Games in Haskell
by John Meacham 26 May '10

26 May '10

On Wed, May 26, 2010 at 01:17:00PM -0700, Evan Laforge wrote: > Unfortunately then you get another cockamamie restriction in the whole > JVM vs. tail calls thing... but if you can get around that then lots > of people will like you a lot. Working on it... :) John -- John Meacham - ⑆repetae.net⑆john⑈ - http://notanumber.net/

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Re: [Haskell] Re: [Haskell-cafe] Work on Video Games in Haskell
by Dan Mead 26 May '10

26 May '10

wouldn't they just want to have TCO happen during the compilation into java? why would you want to output java that has recursion? -Dan On Wed, May 26, 2010 at 4:17 PM, Evan Laforge <qdunkan(a)gmail.com> wrote: >> So, sadly, I think your chances of shipping your a title written in Haskell >> on the iPhone are shot to hell. > > +1 for the android version. > > Disclaimer: biased google employee > > :P > > Unfortunately then you get another cockamamie restriction in the whole > JVM vs. tail calls thing... but if you can get around that then lots > of people will like you a lot. > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe >

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How to implement Association-Lists and Property-Lists in Haskell
by Tom Jordan 26 May '10

26 May '10

Greetings, I'm struggling to find a way to define an "Alist" once, and then simply add-in "Fields" to it incrementally.. without having to keep using new identifiers/variables to hold the result of each "addin" expression. I understand that pure Functional Programming doesn't use destructive state changes, but I'm wondering if there is a way to make this happen using Monads, for example (which I have a cursory understanding of..) Instead of doing this: type Root = String type Oct = Integer type Mode = Integer data Field = Root Root | Oct Oct | Mode Mode deriving (Show) type Alist = [Field] addin :: Alist -> Field -> Alist addin p f = f:p p0 :: Alist p0 = [] p1 = addin p0 (Root "c") p2 = addin p1 (Oct 4) p3 = addin p2 (Mode 3) p4 = addin p3 (Oct 3) -- ... p42, etc For the Alist version, when adding-in a Field with the same constructor-name as one that has already been added-in, it adds-in a brand new entry (with a repeated key-name (in the form of another constructor) and its associated value), as a normal association list does.. I'm also looking to define a Property-List version, where a Field-name/constructor can update a previous value (if the Field has already been added), or add-in a new entry if the Field hasn't been added yet. Many Thanks, Tom Jordan

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Work on Video Games in Haskell
by Ryan Trinkle 26 May '10

26 May '10

iPwn Studios is seeking Haskell developers for its debut title, BloodKnight. * No prior game development experience is required, but you must be very comfortable working in Haskell. * Compensation is negotiable; profit-sharing may be available in some cases. * To apply, or for more information, contact me at ryan(a)ipwnstudios.com. BloodKnight is an action-roleplaying game inspired by games like Diablo and Fallout. It is currently in the final stages of development, and will be released later this year on a variety of smartphone platforms, including iPhone and Android. iPwn Studios is a start-up company located in Boston, MA. We believe in giving back to the Haskell community, so we've open-sourced our ghc-iphone project, which allows GHC to produce binaries for the iPhone. Check it out at http://projects.haskell.org/ghc-iphone/. Ryan Trinkle iPwn Studios

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LOPSTR/PPDP 2010 Call for Participation
by Temur Kutsia 25 May '10

25 May '10

[Apologize for multiple copies] ==================================================================== *** CALL FOR PARTICIPATION *** LOPSTR 2010 20th International Symposium on Logic-Based Program Synthesis and Transformation http://www.risc.jku.at/conferences/lopstr2010/ July 23-25, 2010 PPDP 2010 12th International ACM SIGPLAN Symposium on Principles and Practice of Declarative Programming http://www.risc.jku.at/conferences/ppdp2010/ July 26-28, 2010 Hagenberg, Austria ==================================================================== IMPORTANT INFORMATION Early registration deadline (for both conferences): June 21, 2010 -------------------------------------------------------------------- LOPSTR 2010 INVITED SPEAKERS: - Bruno Buchberger (RISC, Johannes Kepler University Linz, Austria) - Olivier Danvy (University of Aarhus, Denmark) - Johann Schumann (RIACS/NASA Ames Research Center, USA) LOPSTR 2010 PROGRAM: http://www.risc.jku.at/conferences/lopstr2010/program.html -------------------------------------------------------------------- PPDP 2010 INVITED SPEAKERS: - Maria Paola Bonacina (University of Verona, Italy) - Sumit Gulwani (Microsoft Research) PPDP 2010 PROGRAM: http://www.risc.jku.at/conferences/ppdp2010/program.html --------------------------------------------------------------------

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[ANNOUNCE] SyntaxMacros-0.1
by Marcos Viera 25 May '10

25 May '10

We are pleased to announce the first release of SyntaxMacros [1]. SyntaxMacros is an EDSL for constructing compilers out of a collection of pre-compiled, statically type-checked, possibly mutually dependent ``language-definition fragments''. This way of constructing a compiler brings syntax macros for free. This approach is based on a collection of techniques we have previously developed: - transformation of typed abstract syntax trees [2] makes it possible to construct parsers on the fly in a type-safe way - parser combinators [3] make it possible to construct parsers dynamically - first-class attribute grammars [4] make it possible to define semantics in a compositional way More information can be found at: http://www.cs.uu.nl/wiki/Center/SyntaxMacrosForFree Regards, Marcos Viera, Doaitse Swierstra, Atze Dijkstra and Arthur Baars [1]- http://hackage.haskell.org/package/SyntaxMacros [2]- http://www.cs.uu.nl/wiki/Center/TTTAS [3]- http://www.cs.uu.nl/wiki/bin/view/HUT/ParserCombinators [4]- http://www.cs.uu.nl/wiki/Center/AspectAG

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ANNOUNCE: lhc-0.10
by Lemmih 24 May '10

24 May '10

Hiya, It's time for a new release of LHC. LHC is a backend for the Glorious Glasgow Haskell Compiler, adding low-level, whole-program optimization to the system. It is based on Urban Boquist’s GRIN language, and using GHC as a frontend, we get most of its great extensions and features. Essentially, LHC uses the GHC API to convert programs to external core format - it then parses the external core, and links all the necessary modules together into a whole program for optimization. We currently have our own base library (heavily and graciously taken from GHC.) This base library is similar to GHC’s (module-names and all,) and it is compiled by LHC into external core and the package is stored for when it is needed. This also means that if you can output GHC’s external core format, then you can use LHC as a backend. Changes in this release include: * LHC requires GHC-6.12 instead of GHC-6.10. * Much simplified support infrastructure to help minimize software decay. Installation instructions can be found in this blog post: http://lhc-compiler.blogspot.com/2010/05/limited-release.html It should be noted that LHC is in its infancy and should be seen more as a toy than anything else. So, if you want a good Haskell compiler, use GHC. If you want play around with GRIN, LHC might be right for you. The following URLs are of relevance: Wiki: http://lhc.seize.it/ Blog: http://lhc-compiler.blogspot.com/ Hackage: http://hackage.haskell.org/package/lhc-0.10 GRIN: http://www.cs.chalmers.se/~boquist/phd/ -- Cheers, Lemmih

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