--------------------------------------------------------------------------- Haskell Weekly News http://sequence.complete.org/hwn/20090131 Issue 103 - January 31, 2009 --------------------------------------------------------------------------- Welcome to issue 103 of HWN, a newsletter covering developments in the [1]Haskell community. Announcements HDBC v2.0 now available. John Goerzen [2]announced that [3]HDBC v2.0 is now available. Simultaneously, [4]HDBC-sqlite3, [5]HDBC-postgresql, and [6]HDBC-odbc v2.0 have also been uploaded to Hackage. A guide to new features and migration can be [7]found here. Extensible and Modular Generics for the Masses: emgm-0.2. Sean Leather [8]announced the second major release of [9]Extensible and Modular Generics for the Masses (EMGM), a library for generic programming in Haskell using type classes and a sum-of-products view. Improvements over emgm-0.1 include type representation derivation using Template Haskell, documentation improvements, a bimap function, and more. incremental-sat-solver. Sebastian Fischer [10]announced the [11]incremental-sat-solver library, which provides an implementation of the [12]Davis-Putnam-Logemann-Loveland algorithm for the Boolean satisfiability problem. It not only allows solving Boolean formulas in one go, but also adding constraints and query bindings of variables incrementally. data-spacepart - space partitioning data structure[s] (initial release). Corey O'Connor [13]announced the [14]data-spacepart package, the goal of which is to be a collection of space partitioning data structures. Currently, there is only a simple quadtree implementation. Wired 0.2. Emil Axelsson [15]announced a new release of [16]Wired. The most important news in this release is that it now contains a 45nm cell library, which means that you can use Wired to create and analyze modern VLSI designs today! CFP Haskell Symposium 2009. Stephanie Weirich [17]announced a call for papers for the [18]2009 Haskell Symposium in Edinburgh, Scotland. The deadline for submissions is May 8. testpack (first release). John Goerzen [19]announced the release of [20]testpack, a collection of a few utilities for tests: some tools to convert QuickCheck properties into HUnit test cases, and various shortcuts and tools to increase verbosity while running tests in both QuickCheck and HUnit. convertible (first release). John Goerzen [21]announced a new package, [22]convertible. At its heart, it's a very simple typeclass that's designed to enable a reasonable default conversion between two different types without having to remember a bunch of functions. The return type from this conversion is "Either ConvertError a", and conversions are expected to do sanity checking (such as bounds checking when converting to types like Int), so as to produce neither garbage nor exceptions as part of the conversion process. The package also includes instances of the Convertible typeclass for common type conversions. working with numeric types as well as dates and times. Notably, it has code to convert between System.Time types and their Data.Time siblings, and vice versa, a capability I found annoyingly lacking in the standard library. Progress with IDE. Juergen Nicklisch-Franken [23]announced that the [24]Leksah 0.4.0 pre-release is now available. Current features include a Haskell customized editor with candy, project management support based on Cabal, a visual editor for Cabal files, navigation aids, a module browser, session support, and more. Hayoo! beta 0.3. Timo B. [25]announced the next beta version 0.3 of [26]Hayoo!, the Haskell API search engine with find-as-you-type and suggestions. Hayoo! now works even if your browser does not support JavaScript. DecisionTree 0.0. Adrian Neumann [27]announced the [28]DecisionTree package, which provides an implementation of the ID3 algorithm and can be used to classify data with discrete valued attributes. orchid-0.0.7. Sebastiaan Visser [29]announced a new release of [30]Orchid, just another Haskell Wiki. This release features a number of improvements, including a [31]filestore backend, searching, deleting and renaming support, and more. Check out the [32]demo. gitit 0.5. John MacFarlane [33]announced the latest release of [34]Gitit, the multitalented distributed wiki written in Haskell. This release uses the [35]filestore library and hence also supports a darcs backend, and also features optimizations, better search, better diffs, and more. You can check out a [36]running example. filestore 0.1. Gwern Branwen [37]announced [38]filestore 0.1, which provides a uniform, abstract, generic interface for storing versioned files on disk. It allows calling programs to use generic commands to store strings or binary data and perform various queries, such as 'what files are in this repository?' or 'what were the contents of this file at revision XXXXXXX?' or 'give me a diff of this file between revision XXXXXXX and revision YYYYYYY.' Because the interface is abstract, the calling program is insulated from the messy details of the backend (which might be a VCS or a database). Darcs and Git are fully supported. There are plans for a SQLite backend. Scurry :: A cross platform (if you put your mind to it) P2P VPN. John Van Enk [39]announced the release of [40]Scurry, a P2P VPN application written in Haskell (and a little C). Discussion Why binding to existing widget toolkits doesn't make any sense. Achim Schneider began an interesting [41]discussion on the proper approach to GUI toolkits in Haskell. Laws and partial values. Henning Thielemann began [42]a long thread on the semantics of laws (such as the monoid laws). Blog noise [43]Haskell news from the [44]blogosphere. * Sebastian Fischer: [45]Using SmallCheck to Shatter an Audacious Claim. * Xmonad: [46]Quad head xmonad. * Darcs: [47]darcs weekly news #15. * Osfameron: [48]More longest paths, and sick folds.. * Eric Kow (kowey): [49]haskell-ji. * Jeff Heard: [50]Control.Monad.IfElse. * Conal Elliott: [51]What is automatic differentiation, and why does it work?. * Luke Palmer: [52]Fun with PiSigma. * Neil Mitchell: [53]Small scripts with Haskell. * LHC Team: [54]Release notes.. * LHC Team: [55]Thoughts on a new code generator. * Xmonad: [56]contribs review: ThreeColumnsMiddle, CenteredMaster, Mosaic. * Osfameron: [57]There's the nub (snippet in Perl and Haskell). * Malcolm Wallace: [58]codec implementations. * Sebastian Fischer: [59]Fun with Infinite Global Constants. Just-in-time, memoized binomial coefficients. * Chris Done: [60]Some libgd changes. * Luke Palmer: [61]A world without orphans. Luke muses on the benefits to be gained by outlawing orphan instances. * Creighton Hogg: [62]Fear of releasing code. * LHC Team: [63]Thoughts on a new code generator. * Don Stewart (dons): [64]What is Haskell good for?. Lots of things, if this tag cloud has anything to say about it. * Arch Haskell News: [65]Haskell wiki stack in Arch. * Conal Elliott: [66]Comparing formulations of higher-dimensional, higher-order derivatives. * Conal Elliott: [67]Fostering creativity by relinquishing the obvious. * Arch Haskell News: [68]Arch Haskell News: Jan 11 2009. * Dan Piponi (sigfpe): [69]Fast incremental regular expression matching with monoids. A very cool article showing how to use fingertrees storing memoized automaton transition functions to do fast incremental regular expression matching (or, in general, fast incremental lexing). Quotes of the Week * lilac: is happy with his infinite type. it's ducks all the way across and down. * Gracenotes: You are likely to be eaten by a poset * RossMellgren: Apparently 64-bit GHC is sufficiently advanced to be indistinguishable from magic. * cjb: It's all fun and games until somebody loses an IOVar. * sigfpe: If I took some Ritalin, maybe I could write an entire book on Haskell and algebra. * ddarius: Nothing is evaluated until it is. About the Haskell Weekly News New editions are posted to [70]the Haskell mailing list as well as to [71]the Haskell Sequence and [72]Planet Haskell. [73]RSS is also available, and headlines appear on [74]haskell.org. To help create new editions of this newsletter, please see the information on [75]how to contribute. Send stories to byorgey at cis dot upenn dot edu. The darcs repository is available at darcs get [76]http://code.haskell.org/~byorgey/code/hwn/ . 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