Welcome to issue 102 of HWN, a newsletter covering developments in the Haskell community.

Announcements

Monoids and fingertrees. Heinrich Apfelmus posted a nice tutorial explaining the monoid magic behind 2-3 fingertrees.

STM-IO-Hooks-0.0.1. Peter Robinson announced the stm-io-hooks library, which provides an STM monad with commit and retry IO hooks. A retry-action is run (once) in a separate thread if the transaction retries, while commit-actions are executed iff the transaction commits. The code is based on the AdvSTM monad by Chris Kuklewicz, but in addition also ensures some atomicity guarantees for commit-actions.

1000 libraries. Don Stewart announced that Hackage has now reached 1000 packages!

HTTP-4000.0.4 released. Sigbjorn Finne announced that a new release of HTTP, version 4000.0.4, is now available. The main change is the addition of registering a Browser event handler for capturing state changes to the request-response processing pipeline.

Blog noise

• Luke Palmer: Existential Memoization.

• Luke Palmer: The Third Virtue. Luke has a Grand Vision (TM)!

• Darcs: darcs weekly news #14.

• Magnus Therning: More sensible comments on cabal-debian.

• GHC / OpenSPARC Project: Wait and perform.

• LHC Team: Typeclasses are working, now we're missing a bunch of instances....

• Andy Gill: Memoization in GHC. A cool tutorial on how to memoize a pure function with GHC, without changing the function's definition.

• Magnus Therning: Experience with cabal-debian.

• Joachim Breitner: darcswatch uploaded to hackage.

• GHC / OpenSPARC Project: The Strap.

• Real-World Haskell: Bryan O’Sullivan on the Power of Haskell.

• Jeff Heard: Visualizing groundwater nitrate concentration.

• Don Stewart (dons): Open source releases and growth.

• Lennart Augustsson: Performance update on LLVM.

• Arch Haskell News: Piet implementation for Arch.

• Mark Jason Dominus: Triples and Closure. Did you know that monads are like closure operators? If not, read on.

• GHC / OpenSPARC Project: The Grind.

• LHC Team: Functions in Haskell..

• Magnus Therning: Building Debian packages of (cabalised) Haskell packages.

• Xmonad: xmonad cheatsheet.

• Xmonad: xmonad on twitter.

• Jeff Heard: A random note on programming with Gtk2Hs..

• Xmonad: xmonad 0.8.1 : GHC 6.10 maintenance release.

• Jonathan Tang: Some observations on Kinds.

• Martijn van Steenbergen: Type Synonym Families.

Quotes of the Week

• Jonathan Cast: [on advertising for Haskell programmers and informing them that the codebase is actually in Perl at the interview] <Andrew Wagner> That's......evil. <Jonathan> I know. I'm evil too, though. So it's cool.
• rwbarton: A type class is not a type just like a dog house is not a dog.
• SPJ: [This is] clearly not a bug in GHC; but it would be more felicitous if it gave you a warning...
• Gracenotes: > let o_o = 0.0 ;o' =(, ); ;o (*)=(*) ;( lol, xD :p )= o' o' $o.o$ (:[]) $o.o$ (:[]) o_o in (:[]) o_o :p
• Cale: I plan on forming a symbiotic relationship with sandtrout, which, as they merge with my body, will sustain me as I slowly turn into a sandworm, and make use of my billions of other memories and prescience to rule over everyone and everything for millenia.
• quicksilver: or in Java, we'd make it more generic by using a PolynomialDivisionOperatorFactory.
• roconnor: I was going to read about laziness, but I decided to do it later, when I need to understand it.

About the Haskell Weekly News

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