Welcome to issue 34 of HWN, a weekly newsletter covering developments in the Haskell community. Each Monday, new editions are posted to the Haskell mailing list as well as to the Haskell Sequence and Planet Haskell. RSS is also available, and headlines appear on haskell.org.

A double-plus episode this week, as last week's HWN went missing during a furious hack fest.

Announcements

• GHC 6.4.2. Simon Marlow announced the release of the Glasgow Haskell Compiler, version 6.4.2. GHC is a state-of-the-art programming suite for Haskell. Included is an optimising compiler generating good code for a variety of platforms, together with an interactive system for convenient, quick development. The distribution includes space and time profiling facilities, a large collection of libraries, and support for various language extensions, including concurrency, exceptions, and foreign language interfaces (C, whatever). GHC is distributed under a BSD-style open source license.

  For more information, see:
  • GHC home
  • Release no tes
  • GHC developers' home

• Communities and Activities Report. Andres Loeh released the call for contributions to the 10th (!) Haskell Communities and Activities Report. If you are working on any project that is in some way related to Haskell, write a short entry and submit it to Andres.

  The Haskell Communities and 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 6 months. If you have only recently been exposed to Haskell, it might be a good idea to browse the November 2005 edition -- you will find interesting topics described as well as several starting points and links that may provide answers to many questions.

• Haskell' Status Report. Isaac Jones released a Haskell' status report. Currently the committee is focused on two issues, standardising concurrency and extensions to the class system.

• Google Summer of Code. Paolo Martini announced that Haskell.org would have a presence as an official mentoring organisation for this year's Google Summer of Code. Several members of the Haskell community have volunteered as mentors, and a large number of proposals have been listed. If you're interested in mentoring, suggesting projects, or applying as a student to spend your summer writing Haskell code, check it out!

  • The official SoC site
  • The Haskell.org SoC page

• 2006 GHC Hackathon. Simon Marlow writes that the GHC team is considering the possibility of organising a GHC Hackathon around ICFP this year. Tentative details are on the wiki page.

• Data.ByteString. Don Stewart announced new versions of FPS/Data.ByteString, the fast, packed strings library for Haskell.

• Debian from Scratch. John Goerzen announced Debian From Scratch (DFS), a single, full rescue linux CD capable of working with all major filesystems, LVM, software RAID, and even compiling a new kernel. The tool that generates the ISO images (dfsbuild) is written in Haskell. The generated ISO images also contain full, working GHC and Hugs environments.

• Hazakura - search-based MUA. Jun Mukai announced the first release of hazakura, a search-based mail client, written in Haskell.

  • Web
  • Source
  • Darcs

• (HS)XML queries. Oleg Kiselyov published a note demonstrating Scrap your boilerplate 3 style generic term processing for transformations and selections from (HS)XML-like documents.

Haskell'

• Class system status
• Termination for FDs and ATs
• Associated types and two-way functional dependencies
• unsafePerformIO and cooperative concurrency
• Concurrency guarantees
• Control of C headers

Discussion

• Global IORefs. Brian Hulley forked a long running thread on the use of top level mutable variables in an application he's developing, leading to many contributions on how to rewrite the code in a functional style.

• cabal-get. Isaac Jones released a note discussing some changes to Cabal, including integration of the cabal-get tool into the main branch.

• Fast serialisation. Bulat Ziganshin published some result of a test of various serialization libraries speed, comparing his AltBinary code against the standard Binary implementations, with very encouraging results.

• Gigabyte strings. Don Stewart posted the results of some experiments into using gigabyte strings (as ByteStrings) in GHC, with good results.

Darcs corner

• Darcs patcher. Nicholas FitzRoy-Dale announced Darcs patcher, a tool to take a darcs patch file in the and applies it to the source tree in your current working directory. It was written as a tool to keep Bazaar repositories in sync with Darcs, with the Darcs repo being the master. Nicholas writes that he finds darcs much easier to use and less prone to failure.

Contributing to HWN

You can help us create new editions of this newsletter. Please see the contributing information, send stories to dons -at- cse.unsw.edu.au. The darcs repository is available at darcs get http://www.cse.unsw.edu.au/~dons/code/hwn

Greetings, and thanks for reading issue 33 of HWN, a weekly newsletter covering developments in the Haskell community. Each Monday, new editions are posted to the Haskell mailing list and to The Haskell Sequence. RSS is also available. Headlines also go to haskell.org.

Announcements

• Halfs, a Haskell filesystem. Isaac Jones announced the first release of Halfs, a filesystem written in Haskell. Halfs can be mounted and used like any other Linux filesystem, or used as a library. Halfs is a fork (and a port) of the filesystem developed by Galois Connections. In addition, Halfs comes with a virtual machine to make using it extremely easy. You don't need an extra partition or a thumb drive, or even Linux (Windows and Mac OS can emulate the virtual machine). See more at the Halfs site.

• DrIFT-2.2.0. John Meacham released DrIFT-2.2.0, the type sensitive preprocessor for Haskell. It extracts type declarations and directives from modules. The directives cause rules to be fired on the parsed type declarations, generating new code which is then appended to the bottom of the input file. Read more here.

• MissingH 0.14.2. John Goerzen announced version 0.14.2 of MissingH, the library of "missing" Haskell code. Now including support for shell globs, POSIX-style wildcards and more. Check here for more details.

• HAppS - Haskell Application Server 0.8 Einar Karttunen announced HAppS 0.8. The Haskell Application Server version 0.8 contains a complete rewrite of the ACID and HTTP functionalities. Features include:

  • MACID - Monadic framework for ACID transactions.
  • An HTTP Server (outperforms Apache/PHP in informal benchmarks).
  • An SMTP Server.
  • Mail delivery agent.
  • DNS resolver in pure Haskell
  • XML and XSLT. Separate application logic from presentation using XML/XSLT.
  • And more..
  More information on the the HAppS page.

• Index-aware linear algebra. Frederik Eaton announced an index-aware linear algebra library written in Haskell. The library exposes index types and ranges so that static guarantees can be made about the library operations (e.g. an attempt to add two incompatibly sized matrices is a static error). Frederik's motivation is that a good linear algebra library which embeds knowledge of the mathematical structures in the type system, such that misuse is a static error, could mean Haskell makes valuable contribution in the area of technical computing, currently dominated by interpreted, weakly typed languages.

• Crypto-3.0.3. Dominic Steinitz announced Crypto-3.0.3, a new version of the Haskell Cryptography Library. Version 3.0.3 supports: DES, Blowfish, AES, Cipher Block Chaining (CBC), PKCS#5 and nulls padding, SHA-1, MD5 , RSA, OAEP-based encryption (Bellare-Rogaway), PKCS#1v1.5 signature scheme, ASN.1, PKCS#8, X.509 Identity Certificates, X.509 Attribute Certificates. See here for more.

Haskell'

• Concurrency and FFI status
• On Unicode
• The goals of the concurrency standard
• Preemptive versus cooperative scheduling
• Postponing deepSeq and exceptions discussion
• Defaults for superclass methods
• Collecting requirements for FDs
• FDs and confluence
• Network IO

Discussion

• QuickCheck. Koen Claessen hinted that a "brand new" version of QuickCheck with lots of cool features is soon to be released.

• Accurate event scheduling. Henning Thielemann asked about how to improve the accuracy of event scheduling, while working on Haskore, the Haskell music system. John Meacham suggested a binding to the Linux real time clock interface, while Tomasz Zielonka pointed to a library he has been developing using software transactional memory actions for accurate timeouts. He also mentioned the new registerDelay function in the GHC head. Measurements indicated that the average error from the expected waiting time dropped from 0.010140108245s to 0.00080999391s. Quite good results.

• Good fusion. A casual remar k about an alternative version of the inits function lead to a huge discussion about using fusion to improve code quality.

Code watch

• Sun Apr 2 14:59:11 PDT 2006 simonpj
  Improve newtype deriving
  
  Ross Paterson pointed out a useful generalisation of GHC's newtype-deriving mechanism. This implements it. The idea is to allow newtype Wrap m a = Wrap (m a) deriving (Monad, Eq) where the representation type doesn't start with a type constructor.

• Tue Apr 11 05:04:41 PDT 2006 simonpj
  Allow IO to be wrapped in a newtype in foreign import/export
  
  Up to now, the silent unwrapping of newtypes in foreign import/export has been limited to data values. But it's useful for the IO monad itself:

          newtype MyIO a = MIO (IO a)
          foreign import foo :: Int -> MyIO Int

  This patch allows the IO monad to be wrapped too.

Contributing to HWN

You can help us create new editions of this newsletter. Please see the contributing information, send stories to dons -at- cse.unsw.edu.au. The darcs repository is available at darcs get http://www.cse.unsw.edu.au/~dons/code/hwn

Greetings, and thanks for reading issue 32 of HWN, a weekly newsletter covering developments in the Haskell community. Each Monday, new editions are posted to the Haskell mailing list and to The Haskell Sequence. RSS is also available. Headlines also go to haskell.org.

Announcements

• hImerge: a graphical user interface for emerge. Luis Araujo released hImerge, a graphical user interface for emerge, (Gentoo's Portage system) written in Haskell using gtk2hs. Here's a jpg. The main idea is to simplify browsing the entire portage tree as well as of running the most basic and common options from the emerge command. hImerge also offers several handy tools, like global and local use flags browsers, and a minimal web browser.

• MissingH 0.14.0. John Goerzen announced MissingH 0.14.0, a library of "missing" functions. MissingH is available here.

• Haskell mailing list archives. Don Stewart converted the Haskell mailing list archives from 1990-2000, into html format. The archive is available to view here.

• Chapter 4 of Hitchhikers Guide to the Haskell. Dmitry Astapov announced that the 4th chapter of the Hitchhikers Guide to Haskell is now available.
• Edison 1.2 rc3. Robert Dockins announced that the 3rd release candidate for Edison 1.2 is now avaliable.

Haskell'

• State threads
• Terminating instances
• deriving Tree
• deriving Typeable
• deriving for newtypes
• deepSeq
• Asynchronous exceptions
• Exceptions

Code watch

Wed Apr  5 06:33:44 PDT 2006  Simon Marlow
  * add support for x86_64; foreign import is now supported in GHCi on x86_64

Thu Apr  6 10:57:53 PDT 2006  Lemmih
  * GHC.Base.breakpoint isn't vaporware anymore.

  -fignore-breakpoints can be used to ignore breakpoints.

Thu Apr  6 19:05:11 PDT 2006  Simon Marlow
  * Reorganisation of the source tree
  Most of the other users of the fptools build system have migrated to
  Cabal, and with the move to darcs we can now flatten the source tree
  without losing history, so here goes.

  The main change is that the ghc/ subdir is gone, and most of what it
  contained is now at the top level.  The build system now makes no
  pretense at being multi-project, it is just the GHC build system.

Quotes of the Week

JaffaCake :: gcc is getting smarter, so we need to hit it with a bigger stick

ihope :: Oops, I forgot that Djinn doesn't do GADT's.

malig :: quantum mechanics actually strikes me as less weird than lazy
evaluation sometimes. at least it disallows time travel

Contributing to HWN

Thanks to Luis Araujo for help preparing this issue.

You can help us create new editions of this newsletter. Please see the contributing information, send stories to dons -at- cse.unsw.edu.au. The darcs repository is available at darcs get http://www.cse.unsw.edu.au/~dons/code/hwn

Haskell Weekly News: April 03, 2006

Greetings, and thanks for reading issue 31 of HWN, a weekly newsletter covering developments in the Haskell community. Each Monday, new editions are posted to the Haskell mailing list and to The Haskell Sequence. RSS is also available. Headlines also go to haskell.org.

Haskell'

• FFI, 'safe' and 'unsafe', parts 1 and 2
• newtype deriving
• Standardise deepSeq
• MVar semantics
• Thread priorities
• Concurrency, parts 1, 2 and 3.
• FD improvement, variable quantification & generalised propagation

Discussion

• Mobile Haskell. Dmitri O.Kondratiev asked about running Haskell on a PowerPC Windows Mobile device. John Meacham responded with some interesting notes regarding Haskell on the Nokia 770.

• GHCi as a debugger. Lemmih wrote on "whether it would be possible to call GHCi from interpreted byte-code. It turned out that it was, and it was even fairly easy". Great stuff!

• Clearer reflection. Krasimir Angelov proposed some ideas for a better Reflection API for Haskell. Currently we have Typeable and Data classes which provide some pieces of information about the data types at runtime. typeOf provides runtime information about the type of a given variable. dataTypeOf provides almost the same information but with some extras. There is some overlap between the TypeRep and DataType types. Some pieces of information you can get from the TypeRep, other from the DataType and some other from both of them. There is also an information which is inaccessible from either TypeRep and DataType.

Quotes of the Week

Seen on #haskell:

Lemmih:: calling an out-of-scope function isn't as easy as I had hoped

TuringTest:: They got it work in Haskell without understanding Haskell.
It is quite an achievement, of some description.

tennin:: [very #haskell] anyone know of any good books/papers on the
application of category theory to databases?

Smokey`:: I can't believe it, Haskell is starting to draw me away from
C++... I swore i'd never turn from C++

Contributing to HWN

You can help us create new editions of this newsletter. Please see the contributing information, send stories to dons -at- cse.unsw.edu.au. The darcs repository is available at darcs get http://www.cse.unsw.edu.au/~dons/code/hwn

Haskell Weekly News: March 27, 2006

Greetings, and thanks for reading issue 30 of HWN, a weekly newsletter covering developments in the Haskell community. Each Monday, new editions are posted to the Haskell mailing list and to The Haskell Sequence. RSS is also available.

A busy, exciting week!

Announcements

• monadLib 2.0. Iavor Diatchki announced the release of monadLib 2.0 -- library of monad transformers for Haskell. 'monadLib' is a descendent of 'mtl', the monad template library that is distributed with most Haskell implementations. Check out the library web page.

• Text.Regex.Lazy (0.33). Chris Kuklewicz announced the release of Text.Regex.Lazy. This is an alternative to Text.Regex along with some enhancements. GHC's Text.Regex marshals the data back and forth to C arrays, to call libc. This is far too slow (and strict). This module understands regular expression Strings via a Parsec parser and creates an internal data structure (Text.Regex.Lazy.Pattern). This is then transformed into a Parsec parser to process the input String, or into a DFA table for matching against the input String or FastPackedString. The input string is consumed lazily, so it may be an arbitrarily long or infinite source.

• HDBC 0.99.2. John Goerzen released HDBC 0.99.2, along with 0.99.2 versions of all database backends. John says "If things go well, after a few weeks of testing, this version will become HDBC 1.0.0". HDBC is a multi-database interface system for Haskell.

• Planet Haskell. Isaac Jones asked if someone could volunteer to set up "Planet Haskell", an RSS feed aggregator in the style of Planet Debian, Planet Gnome or Planet Perl. Happily, Antti-Juhani Kaijanaho stepped up, and now Planet Haskell is live at http://planet.haskell.org. Antti-Juhani asks that any Haskell people with blogs submit their feed urls to him, so check it out!

• Haskell on Gentoo Linux Duncan Coutts writes that GHC 6.4.1 has been marked stable on x86, amd64, sparc and ppc, for Gentoo Linux. (We also support ppc64, alpha and hppa.) Gentoo also has a collection of over 30 Haskell libraries and tools. There is also a #gentoo-haskell irc channel on freenode.

• Concurrent Yhc. The Yhc dev team reports that Yhc now includes support for concurrency! The interface is the same as Concurrent GHC. Currently only

  • Control.Concurrent
  • Control.Concurrent.MVar
  • Control.Concurrent.QSem

  are implemented, however many other abstractions can be written in Haskell in terms of MVars.

• GHC 6.4.2 Release Candidates Simon Marlow announced that GHC was moving into release-candidate mode for version 6.4.2. Grab a snapshot and try it out. The available builds are: x86_64-unknown-linux (Fedora Core 5), i386-unknown-linux (glibc 2.3 era), and Windows (i386-unknown-mingw32). Barring any serious hiccups, the release should be out in a couple of weeks.

• HaRe 0.3. Sneaking out without us noticing, in January, a new snapshot of HaRe, the Haskell refactoring tool, was released. This snapshot of HaRe 0.3 is now compatible with the latest GHC and Programmatica. New refactorings have also been added.

Haskell'

• Bringing discusison to a close
• Time to focus discussion
• Collections interface
• MonadPlus reform
• Strict tuples
• seq as a class method
• Alternatives to . for composition
• Concurrency
• Pre-emptive or co-operative concurrency
• Liberal type synonyms

Discussion

• Disruptive Haskell. Paul Johnson forked a long discussion on how Haskell can be seen as a disruptive technology, and what Haskell's "brand" might be. Many interesting contributions were made.

• Bit streaming Haskell. Per Gustafsson, having made a proposal to extend the Erlang `binary' data type from being a sequence of bytes (a byte stream) to being a sequence of bits (a bitstream), with the ability to do pattern matching at the bit level, asked for help writing efficient (and beautiful) Haskell versions of his bitstream benchmarks. Several improved programs were submitted, bringing the Haskell code into line with the OCaml and Erlang entries.

Quotes of the Week

Pseudonym's condensed LtU guide to the static types vs dynamic types debate:

• Haskell-vs-Scheme is an issue on which reasonable people differ.
• Ruby-vs-Java is an issue on which unreasonable people differ.

Seen on #haskell:

shapr :: Science News had an article about a tribe of isolated villagers
in Brazil that don't have recursion or indirection in their language.

Contributing to HWN

You can help us create new editions of this newsletter. Please see the contributing information, send stories to dons -at- cse.unsw.edu.au. The darcs repository is available at darcs get http://www.cse.unsw.edu.au/~dons/code/hwn

Haskell Weekly News: March 20, 2006

Greetings, and thanks for reading issue 29 of HWN, a weekly newsletter covering developments in the Haskell community. Each Monday, new editions are posted to the Haskell mailing list and to The Haskell Sequence. RSS is also available.

Announcements

• lhs2TeX version 1.11. Andres Loeh announced lhs2TeX version 1.11, a preprocessor to generate LaTeX code from literate Haskell sources.

  lhs2TeX includes the following features:

  • Highly customized output.
  • Liberal parser -- no restriction to Haskell 98.
  • Generate multiple versions of a program or document from a single source.
  • Active documents: call Haskell to generate parts of the document (useful for papers on Haskell).
  • A manual explaining all the important aspects of lhs2TeX.

Haskell'

• Dropping implicit universal quantification
• Refine overlap handling for instance declarations
• Ranges and the Enum class
• Strict tuples
• Time library
• Associated types

Discussion

• Deep Functors. Oleg Kiselyov described an fmap over arbitrarily deep `collections': lists of maybes of maps of IOs, etc. -- arbitrarily nested fmappable things.

• GHC 6.4.2. Simon Marlow put out a heads up for the forthcoming 6.4.2 release of GHC. The rough timescale is to go into release candidate testing in about a week, and have two weeks of release candidates before the final release.

• Hexdump. Dominic Steinitz mentioned a "hexdump" function he'd written, posing a question about where it would live in the module hierarchy..

Quote of the Week

ihope :: My factorial function uses GADTs.

Contributing to HWN

You can help us create new editions of this newsletter. Please see the contributing information, send stories to dons -at- cse.unsw.edu.au. The darcs repository is available at darcs get http://www.cse.unsw.edu.au/~dons/code/hwn

Haskell Weekly News: March 13, 2006

Greetings, and thanks for reading issue 28 of HWN, a weekly newsletter covering developments in the Haskell community. Each Monday, new editions are posted to the Haskell mailing list and to The Haskell Sequence. RSS is also available.

Announcements

• Alternative to Text.Regex. Chris Kuklewicz announced an alternative to Text.Regex. While working on the language shootout, Chris implemented a new efficient regex engine, using parsec. It contructs a parser from a string representation of a regular expression.

• pass.net. S. Alexander Jacobson launched Pass.net. Written in Haskell, using HAppS, Pass.net lets websites replace registration, confirmation mails, and multiple passwords with a single login, authenticating via their email domain.

Haskell'

• Partial application syntax
• Extending the `...` notation
• The dreaded offside rule
• Strictness standardization

Discussion

• Non-trivial markup transformations. Further on last week's article on encoding markup in Haskell, Oleg Kiselyov demonstrates non-trivial transformations of marked-up data, markup transformations by successive rewriting (aka, `higher-order tags') and the easy definition of new tags.

• Popular libraries and tools. John Hughes posted (and here) some interesting figures on the most important libraries and tools, based on the results of his survey of users earlier this year.

• haskell-prime fun. Just for fun, Ross Paterson posted, some thought-provoking statistics on haskell-prime traffic.

• New collections package. Jean-Philippe Bernardy hinted that his new collections package is almost done.

• Is notMember not member? John Meacham sparked a bit of a discussion on whether negated boolean functions are useful with a patch adding Data.Set and Data.Map.notMember.

• Namespace games. In a similar vein, Don Stewart triggered discussion on how to sort the hierarchical namespace, when proposing alternatives to the longish Text.ParserCombinators module name.

Darcs Corner

• Darcs-server. Unsatisified with the current techniques for centralised development with darcs, Daan Leijen went ahead and wrote darcs-server. With darcs-server you can:

  • push changes remotely via a CGI script
  • or push changes via a single SSH account that serves many users
  • use cryptographic verification and authorization of users for reading and writing
  • use gpg encryption (for CGI)
  • use non-public repositories that can only be accessed by authorized users.

• darcsweb 0.15, by Alberto Bertogli, has been released.

Contributing to HWN

You can help us create new editions of this newsletter. Please see the contributing information, send stories to dons -at- cse.unsw.edu.au. The darcs repository is available at darcs get http://www.cse.unsw.edu.au/~dons/code/hwn

Haskell Weekly News: March 06, 2006

Greetings, and thanks for reading issue 27 of HWN, a weekly newsletter covering developments in the Haskell community. Each Monday, new editions are posted to the Haskell mailing list and to The Haskell Sequence. RSS is also available.

Announcements

• Haskell as a markup language. Oleg Kiselyov writes on using Haskell to represent semi-structured documents and the rules of their processing. SXML is embedded directly in Haskell, with an open and extensible set of `tags'. The benefit of this is of course in static type guarantees, such as prohibiting an H1 element to appear in the character content of other elements.

• hmp3 1.0. Don Stewart released hmp3 version 1. hmp3 is a curses-based mp3 player written in Haskell, designed to be fast, small and stable.

• Edison 1.2rc2. Robert Dockins announced the second release candidate for Edison 1.2 is now ready for comments.

Haskell'

• Overlapping instances and constraints
• realToFrac
• instance Functor Set
• Keep the present Haskell record system!
• Relaxed instance rules spec
• Collections
• Partial type signatures/annotations/declarations..
• How to create a proposal

Discussion

• Library Reorganisation. Simon Marlow opened up a discussion on library reorganisation, in the light of the oncoming Haskell'.

• Deprecating FunctorM. Ross Paterson proposes to replace FunctorM with Data.Traversable.

• cabal-setup. Simon Marlow posted a patch to wrap the Setup.hs Cabal script with a generic cabal-setup interface.

Code Watch

• Make -split-objs work with --make.

  Thu Mar  2 09:05:05 PST 2006  Simon Marlow
    * Make -split-objs work with --make
  
    This turned out to be a lot easier than I thought.  Just moving a few
    bits of -split-objs support from the build system into the compiler
    was enough.  The only thing that Cabal needs to do in order to support
    -split-objs now is to pass the names of the split objects rather than
    the monolithic ones to 'ar'.
  

Quotes of the Week

[OConnor's Law]
roconnor :: As an online discussion of static types vs dynamic types grows longer, the 
            probability of mentioning heterogenous lists approaches 1.

[Lemmih's Law]
Lemmih :: Every 18 months, compilers will make their warnings and error messages twice as cryptic

Claus Reinke :: The point about overlapping instances is that they shouldn't.

Contributing to HWN

You can help us create new editions of this newsletter. Please see the contributing information, send stories to dons -at- cse.unsw.edu.au. The darcs repository is available at darcs get http://www.cse.unsw.edu.au/~dons/code/hwn

Haskell Weekly News: February 27, 2006

Greetings, and thanks for reading issue 26 of HWN, a weekly newsletter covering developments in the Haskell community. Each Monday, new editions are posted to the Haskell mailing list and to The Haskell Sequence. RSS is also available.

A fairly quiet week this week.

Announcements

• Long Live Edison. Robert Dockins announced he had revived the Edison data structure code, and is maintaining a darcs repository, with a view to modernising the codebase.

Haskell'

• The hierarchical module system
• Refactoring the array interface
• The worst syntax in Haskell
• Module export lists
• Public/private sections part 1 and part 2

Darcs Corner

• darcsweb 0.15-rc1. Alberto Bertogli announced that a new version of darcsweb is available.

Contributing to HWN

You can help us create new editions of this newsletter. Please see the contributing information, send stories to dons -at- cse.unsw.edu.au. The darcs repository is available at darcs get http://www.cse.unsw.edu.au/~dons/code/hwn

Haskell Weekly News: February 20, 2006

Greetings, and thanks for reading issue 25 of HWN, a weekly newsletter covering developments in the Haskell community. Each Monday, new editions are posted to the Haskell mailing list and to The Haskell Sequence. RSS is also available.

Announcements

• The Haskell Workshop. Andres Loeh released the initial call for papers for the ACM SIGPLAN 2006 Haskell Workshop, to be held at Portland, Oregon on the 17 September, 2006.

  The purpose of the Haskell Workshop is to discuss experience with Haskell, and possible future developments for the language. The scope of the workshop includes all aspects of the design, semantics, theory, application, implementation, and teaching of Haskell.

• Probability Distributions. Matthias Fischmann released a module for sampling arbitrary probability distribution, so far including normal (gaussian) and uniform distributions.
• Constructor Classes. Sean Seefried announced an implementation of a tool to help explore constructor classes (type classes which can take constructors as arguments) described in Mark Jones' paper, A system of constructor classes: overloading and implicit higher-order polymorphism. The implementation not only infers the type but also prints out a trace of the derivation tree for the syntax directed rules.

Haskell'

• Status Report. Isaac Jones released a Haskell' status report. There is a list of proposals and a "strawman" categorization of them on the wiki. The timeline is also on the wiki. You'll notice that it's very aggressive; we plan to announce something at the next Haskell Workshop in September. So, check out the wiki and get on the haskell-prime mailing list!

• More on strictness
• FFI Pragmas
• Pattern synonyms
• The MPTC Dilemma
• Labels and the MPTC Dilemma
• The way forward
• Export lists
• First class labels
• Standardising the compiler interface
• An existential quantifier

Discussion

• Commerical Use of Haskell. Seth Kurtzberg mentioned on the #haskell irc channel that he was in the process of deploying a commercial application written in Haskell onto a production line in Taiwan. The particular application stress tests hardware performance and stability.

  Seth writes:

  Once the compiler finally does what I think I'm telling it, the programs almost always work the first time, which is really amazing. With any substantial effort in C or C++, you are going to have hidden problems traceable to type errors.

  Recently, the thing that I was most pleased with was how quickly I was able to refactor the hardware stress testing code into network performance testing code.

• RFC: Class-based collections. Jean-Philippe Bernardy released an rfc for his initial work on a class-based collections framework. The main goal is to have something usable right now, making use of generally available haskell extensions for maximum usability/portability ratio (or rather product).

Darcs Corner

• darcs 1.0.6. Tommy Pettersson announced that the initial release candidate for Darcs 1.0.6 is available. It contains important bug fixes, some noticeable changes, and, of course, new features.

Contributing to HWN

You can help us create new editions of this newsletter. Please see the contributing information, send stories to dons -at- cse.unsw.edu.au. The darcs repository is available at darcs get http://www.cse.unsw.edu.au/~dons/code/hwn