Top picks:

Simon Marlow, who built much of GHC's runtime, now works at Facebook. He contributes to Haxl, a tool to "automatically batch and overlap requests for data from multiple data sources in a rule engine for identifying malicious content."

In a talk last year at FP Days, he explains how you too can use Haxl in your projects. The video was just made available at InfoQ. Hat-tip to redditor Pikachut for links to slides and code.
GHC builds can be frightfully slow. Karel Gardas wonders how he can speedup builds on his 32-threaded SPARC T2000. Folks point him toward Andrey Mokhov's ongoing investigation of Neil Mitchell's shake to replace GHC's current use of GNU make. SPJ hopes that it "will make a big difference."
Back in September last year, Ahmad Fatoum asks whether we can fix the Win32 FFI so that it supports optional params? Some Win32 functions -- e.g. see FindWindow -- accept NULL pointers as invocation of default behavior, currently impossible from Haskell.

One option is to make copies of over 100 functions to prevent existing client code from breaking. A more radical one is to extend the existing FFI in-place and alter the type signatures by Maybe-fying the params that are actually optional.

The vocal opinion is in favor of the latter, deeper fix. Yitzchak Gale recently brought up the issue on haskell-libraries.
Maurizio Vitale asks for a way to extract verbatim a single definition from Haskell source. Michael Sloan shows a way to do it using haskell-src-exts.
Conor McBride discusses Naperian / Representable functors as a subclass of Applicative. Elsewhere in the thread, Ed Kmett remarks that "The Log of a coinductive container being an inductive type is a new result for me."
A subreddit called haskelltil (TIL = Today I Learned) for little discoveries was announced on haskell reddit.

Repo of the week: Calvin Cheng, co-founder and CTO at AlgoAccess, releases code and slides on learning Haskell for the OO programmer.

In your neighborhood:

Kat Chuang organized an NYC-based study group to dissect Nishan Shukla's Haskell Data Analysis Cookbook. "This is your AHA! Haskell Moment."
Redditor netroby launched a QQ instant messaging group, code number 424801832, to talk Haskell.

Quote of the week:

Dimitri DeFigueiredo says about the haskell-beginners mailing list, "This is the friendliest mailing list I have ever subscribed to. The people in this list are so nice that even if Haskell were not so wonderfully elegant, I would like to learn it just to be able to chat and work with them."

Acknowledgments

Thanks to Henk-Jan van Tuyl for help with the Quotes. Thanks to Gershom Bazerman, Roman Cheplyaka, and Artyom for offering assistance on web hosting HWN.

Letter to the Editor:

Can I just say that I'm very much in favour of the new format. There's interesting content that can't just be gained from occasionally checking reddit, there's an actual comment on each one rather than just the headline, and most importantly the quote is still there ;)

Sorry if this is adding to a deluge of email that you're now getting because of this.

Yours, Anon

Response:

Dear Anon,

Glad you're enjoying HWN as much as I do creating and publishing it.

I love the quotes too, and I depend on my readers to email me what they'd like to share with Team Haskell.

(Sneak peak at the top-secret contingency plan: If I don't have quotes for the week, I ransack the archives. Shhh!! Don't tell anyone.)

Yours is the only thank you I received. Appreciation like yours is what keeps HWN going, so let me thank you in return for sharing the love, for I remain

Yours editorially, Kim-Ee Yeoh

p.s. Stay tuned for an upcoming editorial on what the future holds for HWN.

-- Kim-Ee