[Haskell-cafe] Haskell Weekly News

[Kim-Ee Yeoh]

*Top picks:*

   - Bot attack on Trac
   <https://mail.haskell.org/pipermail/ghc-devs/2015-March/008557.html>
   pummels GHC HQ productivity! Do you know a thing or two about hardening web
   apps? Can you help?

   - A month ago
   <http://haskell.1045720.n5.nabble.com/Haskell-Weekly-News-td5766529.html>
   you read about the absence of a correct operational spec for Core.
Christiaan
   Baaij <http://ghc.haskell.org/trac/ghc/ticket/10121#comment:7> proffers
   rewriting rules for something "very much like Core" from his 2014 thesis on
   Digital Circuits in CλaSH, a tool designed for Computer Architecture for
   Embedded Systems (CAES). The consensus is that they probably also work for
   GHC Core.

   - Neil Mitchell reports Unable to load package Win32-2.3.1.0
   <https://ghc.haskell.org/trac/ghc/ticket/10165>. The problem?
   SetWindowLongPtrW exists only on 64-bit. The haskell win32 shim wasn't
   switching to SetWindowLongW on 32-bit. Darren Grant steps up to offer a
   fix, which Austin Seipp promptly checks in.

   - Ki Yung Ahn
   <http://haskell.1045720.n5.nabble.com/Do-we-have-idiom-for-lifting-a-state-monad-into-pair-of-states-td5767673.html>
   asks for a "wrapper that lifts actions of (State s1 a) to (State (s1,s2)
   a). " The answer? A function called "zoom" in lens libraries.

   - Chris Done
   <https://groups.google.com/forum/#!msg/commercialhaskell/lRTDiTLIKi0/Kw0UGwa4c0sJ>
   has started the ball rolling on GPG-based package signing. So far, Michael
   Snoyman and Neil Mitchell have had their keys signed by Chris. He invites
   others to join the party.

   - Levant Erkok <https://ghc.haskell.org/trac/ghc/ticket/10215> joins Lennart
   Augustsson <https://ghc.haskell.org/trac/ghc/ticket/9238> in hitting a
   bug with signed zeros <http://en.wikipedia.org/wiki/Signed_zero>. The
   function isNegativeZero breaks under optimizations.

   - James Stevenson
   <https://blog.safaribooksonline.com/2015/03/30/high-performance-log-parsing-in-haskell-part-one/>
   over at Safari Books Online reveals how they use Haskell to parse web logs
   more efficiently than Python. The top comment
   <https://news.ycombinator.com/item?id=9294036> at Hacker News observes
   the absence of a proper benchmark pitting Python vs Haskell. James responds
   that they did an informal comparison that showed "the number of lines
   parsed/second [with Python] was far smaller than the attoparsec-based
   parser."

   Elsewhere, Luke Randall
   <http://www.reddit.com/r/haskell/comments/30xugp/highperformance_log_parsing_in_haskell_part_one/>
   submits the link on reddit and thinks it's a "very gentle intro to parsing
   using attoparsec".

   - Ian Ross
   <http://www.skybluetrades.net/blog/posts/2015/03/30/c2hs-snowmelt.html>
   announces a new C2HS release christened "Snowmelt". Originally authored by
   Manuel Chakravarty, C2HS eases the pain of manually creating FFI shims for
   C libraries. The latest release, thanks to work contributed by Philipp
   Balzarek, achieves better cross-language alignment of C enum and Haskell
   Enum types, among other improvements. Reddit discussion here.


   <http://www.reddit.com/r/haskell/comments/30u8pk/new_c2hs_release_0251_snowmelt/>
   - Michael Snoyman
   <https://www.fpcomplete.com/blog/2015/03/announce-ide-backend> announces
   FPComplete's open sourcing of their IDE backend, comprising a wrapper
   around the GHC API.

   - Jon Sterling at PivotCloud
   <https://ghc.haskell.org/trac/ghc/ticket/9539#comment:2> hits an STM
   TQueue bug initially reported by John Lato seven months ago. A sufficiently
   fast writer can cause the reader to never get scheduled, which leads to
   live-lock in Jon's production code. The fix looks to be as simple as
   lazifying a case into a let in readTQueue. Curiously, the code uses
let in Simon
   Marlow's book on Haskell concurrency
   <http://chimera.labs.oreilly.com/books/1230000000929/ch10.html#CO37-2>
   but not in the STM package you have on your machine.


*Tweets of the week:*

   - Michael Neale
   <https://twitter.com/michaelneale/status/567532684595851264>: Haskell
   Quickcheck enters a bar, asks for 1 beer, 42 beers, -Inifinity beers,
   shaves bartenders beard, sets off a tactical nuke.

   - Dierk König <https://twitter.com/mittie/status/582803534950862848>:
   #Haskell is the gold standard for programming languages and #Frege makes it
   available on the #JVM


-- Kim-Ee
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