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ARRAY 2016 extended deadline: April 11

General haskell list - Fri, 04/01/2016 - 2:53pm
*************************************************************************** CALL FOR PAPERS ARRAY 2016 3rd ACM SIGPLAN International Workshop on Libraries, Languages and Compilers for Array Programming Santa Barbara, CA, USA June 14, 2016 http://conf.researchr.org/home/array-2016/ EXTENDED DEADLINE: April 11, 2016 (FIRM!) *************************************************************************** ARRAY 2016 is part of PLDI 2016 37th Annual ACM SIGPLAN Conference on Programming Language Design and Implementation June 13-17, 2016 http://conf.researchr.org/home/pldi-2016/ *************************************************************************** About: Array-oriented pro
Categories: Incoming News

introspection -- towards type algebra

haskell-cafe - Fri, 04/01/2016 - 4:12am
I am looking for how far algebra on types in the manner of "set theory as an algebra" ¹ is possible. So for example in set theory one can compute for sets S, T S∪T, S∩T, S-T etc Is something similar possible for types? Say I have data Primary = Red|Green|Blue data Othercolors = Violet|Indigo|Yellow|Orange I want something like Rainbow = Primary ∪ Othercolors Equivalently if Rainbow and Primary had been defined, how to get/compute Rainbow - Primary? ------------------------- I thought the first-class types in Idris would be a good bet to try out at least a trivial prototype. Seems not... So asking here. Clearly and obviously one can use haskell to implement any language. My question is what/which are the introspective libraries/features of modern haskell that make this easy and lightweight. Thanks Rusi ¹ Yeah the term 'type algebra' may be taken in the sense of algebraic data types Cant think of a better one _______________________________________________ Haskell-Cafe mailing list Haskell-
Categories: Offsite Discussion

A better type signature for `forM_`

libraries list - Fri, 04/01/2016 - 12:21am
Hi all, I was recently faced with some unexpected behaviour from a piece of code that type checks and has zero warnings (even with -Wall). The code is below (and depends on the hashtables package). The error was using the <$> operator instead of the =<< operator. Using the former, it just builds up a list of IO actions that never get run. As pointed out to me on IRC (thanks pjdeport), chaning the type signature of `forM_` to forM_' :: (Monad m, Foldable t) => t a -> (a -> m ()) -> m () would have resulted in an error. Yes, this change would break existing code (breaking code would require an explicit `void $` inside the `forM_`) but does anyone else think this is a good idea? Erik import Control.Monad import qualified Data.HashTable.IO as HT type EvenCache = HT.BasicHashTable Int Bool main :: IO () main = do ht <- buildTable xs <- HT.toList ht putStrLn $ "cache: length " ++ show (length xs) buildTable :: IO EvenCache buildTable = do ht <- HT.new forM_ pairs $ \ (k,v) -
Categories: Offsite Discussion

Postdoc ad: quantum-computing programming languages

haskell-cafe - Thu, 03/31/2016 - 9:05pm
My institution just bought a D-Wave 2X adiabatic quantum computer. The problem is, no one really has a grasp on how to *program* an adiabatic quantum computer. It's a totally different beast from the gate-model quantum computers that most people imply when they talk about quantum computing. I'm looking to hire a postdoc to work with me on designing and implementing programming models suitable for execution on D-Wave-style quantum computers. The formal job ad can be found at http://tinyurl.com/jdlo556 or go to http://jobs.lanl.gov/ and look up job IRC49031. Disclaimer: This is not specifically a Haskell-hacking position, although you can use any language you want for the classical-side development. I'm posting here because a key skill I'm looking for is breadth of language knowledge. I see a candidate who knows nonstrict functional programming, declarative programming, and maybe a few "fringe" programming models as more valuable than one who knows only a dozen isomorphic imperative languages.
Categories: Offsite Discussion

Postdoc ad: quantum-computing programming languages

General haskell list - Thu, 03/31/2016 - 9:04pm
My institution just bought a D-Wave 2X adiabatic quantum computer. The problem is, no one really has a grasp on how to *program* an adiabatic quantum computer. It's a totally different beast from the gate-model quantum computers that most people imply when they talk about quantum computing. I'm looking to hire a postdoc to work with me on designing and implementing programming models suitable for execution on D-Wave-style quantum computers. The formal job ad can be found at http://tinyurl.com/jdlo556 or go to http://jobs.lanl.gov/ and look up job IRC49031. Disclaimer: This is not specifically a Haskell-hacking position, although you can use any language you want for the classical-side development. I'm posting here because a key skill I'm looking for is breadth of language knowledge. I see a candidate who knows nonstrict functional programming, declarative programming, and maybe a few "fringe" programming models as more valuable than one who knows only a dozen isomorphic imperative languages.
Categories: Incoming News

hslua and language-lua need new maintainers

haskell-cafe - Thu, 03/31/2016 - 5:18pm
Hi all, I need new maintainers for my packages hslua[1] and language-lua[2]. None of these packages is super popular so it's not going to be a lot of work. I just need someone to take care of new issues and pull requests. + points if the maintainer is a user of the library :-) I just don't have time and motivation to maintain those as I'm not a user anymore. Some background, lanugage-lua was the first Haskell program I've written (according to git logs, 3 years 6 months ago). I maintained it over the years and used in some projects. Currently Eric Mertens (glguy) is also a maintainer who occasionally sends some patches, but I need someone to take care of the new issues and pull requests. One thing you may want to do is to merge Eric's patch that ports the parser to Happy (currently it's Parsec) and improves the performance significantly. hslua was originally written by Gracjan Polak. I was using it and sending some patches and eventually I became the maintainer, created a Git repo, wrote some blogs post
Categories: Offsite Discussion

Deriving Eq and Show instances for testing

haskell-cafe - Thu, 03/31/2016 - 4:43pm
I have datatypes for which I need an Eq and Show instance only for testing. I could derive those instances in the datatype declaration but I prefer not to add unnecessary functionality. With StandaloneDeriving extension I can derive the instances in the test module but this produces many warning about orphan instances. Is there a better approach or a way to stop reports about orphan instance warnings? Regards _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe< at >haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe
Categories: Offsite Discussion

ghc 7.10.3 crashes frequently on Windows

haskell-cafe - Thu, 03/31/2016 - 4:37pm
I have installed ghc from Haskell Platform version 7.10.3. When I run QuickCheck or HSpec tests interactively, every so often ghc crashes when I reload a file form withing Emacs and haskell mode. This problem manifested in earlier versions as well. Loading a file which does not contain tests never crashes ghc so far. How could I try to identify the cause of the crash? _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe< at >haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe
Categories: Offsite Discussion

cabal: --enable-tests by default

haskell-cafe - Thu, 03/31/2016 - 3:11am
In the future, could cabal --enable-tests by default when `cabal install`ing local project directories? Other languages' package managers automatically do this, a more intuitive default behavior.
Categories: Offsite Discussion

Testing Msgpack system

haskell-cafe - Thu, 03/31/2016 - 12:41am
Dear friends, we have a distributed system written in Haskell, consisting of three types of nodes with dozen of instances of each of two types and a central node of the third type. Each node is started by executing a binary which sets up acid-state persistence layer and sockets over which msgpack messages are sent around. It is trivial to write low level functionality quickcheck test suites, which test properties of functions. We would like, however, to have a quickcheck-esque suite which sets up the network, then gets it to an arbitrary valid state (sending correct messages between nodes), then rigorously testing it for three high-level properties: 1. Chaos monkey test (disable random node, see if certain invariants hold); 2. Evil node test (make several nodes work against the system, see if certain properties hold); 3. Rigorous testing of network-wide invariants, if all the nodes operate correctly. The problem we're facing is the following — if we want to inspect state of nodes in Haskell-land, we
Categories: Offsite Discussion

Melbourne Haskell Users Group Meetup, Tonight,31-03-2016 < at > 6:30pm

haskell-cafe - Wed, 03/30/2016 - 11:00pm
Hi All, Tonight we're having our monthly Haskell meetup in the Melbourne CBD. Please come along if you're interested and free! http://www.meetup.com/Melbourne-Haskell-Users-Group/events/228915323/ Hope to see you there :) Regards, - Lyndon _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe< at >haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe
Categories: Offsite Discussion

Sponsored: The 3 Week Diet

del.icio.us/haskell - Fri, 03/25/2016 - 2:00am
8 Rules of Fat Loss. Warning: Fast Results! Click Here to Watch Video...
Categories: Offsite Blogs

New gtk2hs 0.12.4 release

gtk2hs - Wed, 11/21/2012 - 12:56pm

Thanks to John Lato and Duncan Coutts for the latest bugfix release! The latest packages should be buildable on GHC 7.6, and the cairo package should behave a bit nicer in ghci on Windows. Thanks to all!

~d

Categories: Incoming News