[Haskell-cafe] Haskell Weekly News: Issue 168 - February 09, 2011

Daniel Santa Cruz dstcruz at gmail.com
Thu Feb 10 03:15:30 CET 2011

   Welcome to issue 168 of the HWN, a newsletter covering developments in
   the [1]Haskell community. This release covers the week of January 30 to
   February 5, 2011.


   Maciej Piechotka [2]announced version 0.1.1 of nanoparsec. "Nanoparsec
   is currently simply a port of attoparsec on ListLike (the abstraction
   of lists used by iteratee)."

   Graham Hutton [3]announced the availability of studenships in
   Functional Programming at the University of Nottingham, UK.

   Ashley Yakeley [4]made a small update to time ( that "fixes a
   bug in parseTime."

   George Giorgidze [5]announced the release to Hackage of Database
   Supported Haskell (DSH).

   Simon Hengel [6]announced the release of HackageOneFive, "a tiny Snap
   app that provides reverse dependency lookup for all packages on

Quotes of the Week

     * alpounet: map succ/pred is a scandinavian name generator or what?
       ... well, scandinavian and aztec
     * dons: Think of a monad as a spacesuit full of nuclear waste in the
       ocean next to a container of apples. Now, you can't put oranges in
       the space suite or the nuclear waste falls in the ocean, *but* the
       apples are carried around anyway, and you just take what you need.
     * Apocalisp: a unit of clarity is a clarinet
     * roconnor: My coq has failed me
     * roconnor: I mean, I could, and do, say that a lens is just a monoid
       natural transformation from the coalgebra functiors from haskell
       functors to haskell types.
     * Saizan: "not being ML" is a quite sound principle syntax-wise
     * lpsmith: well, getting rid of airliners certainly *is* one way of
       eliminating their potential use as weapons against larger buildings
     * ddarius: The reason edwardk writes so many Haskell packages is to
       ward the Perl from penetrating his heart.
     * monochrom: most people tend to deny the usefulness of useful
       alternative perspectives --- their entrenched vested interests
       demand it. as they grow older they also have more influence and
       power over "the state of the art" to preserve their self-fulfilling
       prophecy that "the alternative is useless" --- by controlling what
       practice looks like, they can control what looks useless.
     * edwardk: i learned to program becaise i'd lied and told a kid that
       i'd written a disassembler, then had to make good on the claim.

Top Reddit Stories

   * Quine Central ... because everyone needs to be able to make nth
order quines
     Domain: blog.sigfpe.com, Score: 40, Comments: 7
     On Reddit:
     Original: http://blog.sigfpe.com/2011/01/quine-central.html

   * jhc 0.7.7 is out
     Domain: haskell.org, Score: 38, Comments: 0
     On Reddit: http://www.reddit.com/r/haskell/comments/fbqo7/jhc_077_is_out/
     Original: http://www.haskell.org/pipermail/jhc/2011-January/000874.html

   * Hulk: A Haskell IRC server
     Domain: chrisdone.com, Score: 32, Comments: 1
     On Reddit:
     Original: http://chrisdone.com/posts/2011-01-30-hulk-haskell-irc-server.html

   * Status update on {code, trac, projects, planet, community}.haskell.org
     Domain: haskell.org, Score: 25, Comments: 0
     On Reddit:
     Original: http://www.haskell.org/pipermail/haskell-cafe/2011-February/088829.html

   * All about MVars : Inside T5
     Domain: blog.ezyang.com, Score: 23, Comments: 4
     On Reddit:
     Original: http://blog.ezyang.com/2011/02/all-about-mvars/

   * Text: a visual programming language based on Haskell, demo
     Domain: vimeo.com, Score: 21, Comments: 3
     On Reddit:
     Original: http://vimeo.com/19273744

   * [SO] Why is GHC so big?
     Domain: stackoverflow.com, Score: 21, Comments: 10
     On Reddit:
     Original: http://stackoverflow.com/questions/4858585/why-is-ghc-so-large-big

   * Haskell Weekly News: Issue 167
     Domain: contemplatecode.blogspot.com, Score: 21, Comments: 0
     On Reddit:
     Original: http://contemplatecode.blogspot.com/2011/02/haskell-weekly-news-issue-167.html

   * The F# Team are Hiring (functional programming jobs)
     Domain: haskell.org, Score: 20, Comments: 6
     On Reddit:
     Original: http://www.haskell.org/pipermail/haskell/2011-January/022523.html

   * Recently Uploaded: DSH-0.4.2 Natural Sql Queries without the need
to write Sql strings.
     Domain: hackage.haskell.org, Score: 20, Comments: 2
     On Reddit:
     Original: http://hackage.haskell.org/package/DSH

   * Specifying behaviors in a purely functional language
     Domain: io7m.com, Score: 16, Comments: 0
     On Reddit:
     Original: http://io7m.com/articles/itefs/

Top StackOverflow Answers
   * Why is GHC so large/big?
     votes: 29
     Read on SO:

     It's a bit silly really.  Every library that comes with GHC is provided
     in no less than 4 flavours:


     The GHCi version is just the static version linked together in a single .o
     file.  The other three versions all have their own set of interface files
     (.hi files) too.  The profiled versions seem to be about twice the size
     of the ...

   * Why `(map digitToInt) . show` is so fast?
     votes: 24
     Read on SO:

     Seeing as I can't add comments yet, I'll do a little bit more work and
     just analyze all of them.  I'm putting the analysis at the top; however,
     the relevant data is below.  (Note: all of this is done in 6.12.3 as
     well - no GHC 7 magic yet.)


     Version 1: show is pretty good for ints, especially those as short as we
     have.  Making strings actually ...

   * What Justification for the type of f x = f x in Haskell is there?
     votes: 15
     Read on SO:

     Okay, starting from the function definition f x = f x, let's step through
     and see what we can deduce about the type of f.

     Start with a completely unspecified type variable, a. Can we deduce more
     than that? Yes, we observe that f is a function taking one argument, so
     we can change a into a function between two unknown type variables,
     which we'll call b -> ...

   * . versus $ in haskell
     votes: 14
     Read on SO:

     Prelude> :t ($)
     ($) :: (a -> b) -> a -> b
     Prelude> :t (.)
     (.) :: (b -> c) -> (a -> b) -> a -> c

     $ applies a function to a value.
     . composes two functions.

     So I can write f $ g x which is "apply f to (g of x)" or f . g $ x which
     is "apply the composition of f and g to x". One common style is to pile
     up dots on the left with a ...

   * Starting a game development in an exotic language I am just
learning (Lisp, Haskell, ...)
     votes: 12
     Read on SO:

     If you could write a game in C, you can write one in Haskell. The biggest
     difficulties many people have with it are:

     Lack of support for OOP, which is what most people are familiar with these
     days. Old-fashioned procedural code, on the other hand, is actually very
     pleasant to write in Haskell; the IO type distinguishes effect-free
     functions from procedures ...

   * Haskell: Check if Int is in a list of Int's
     votes: 11
     Read on SO:

     First find the type of the function you need.

     To "Check if" means to return either True or False, a Bool.

     So the function takes an Int, a list of Int (aka [Int]) and returns Bool:

     Int -> [Int] -> Bool

     Now ask hoogle.

     elem :: Eq a => a -> [a] -> Bool

     Hoogle is a very useful tool. You can integrate it with ghci.

Top StackOverflow Questions

   * Why is GHC so large/big?
     votes: 32, answers: 5
     Read on SO:

   * Starting a game development in an exotic language I am just
learning (Lisp, Haskell, …)
     votes: 16, answers: 10
     Read on SO:

   * Why `(map digitToInt) . show` is so fast?
     votes: 8, answers: 2
     Read on SO:

   * Transforming expression given in prefix notation, identifying
common subexpressions and dependencies
     votes: 7, answers: 6
     Read on SO:

   * Practical use of curried functions?
     votes: 7, answers: 6
     Read on SO:

About the Haskell Weekly News

   You can find an html version of this newsletter at:

   To help create new editions of this newsletter, please send stories to
   dstcruz at gmail.com. I'm in dire need of finding good "quotes of the
   week". If you happen to come across any, please don't hesitate to send
   it along.

   Until next time,
   Daniel Santa Cruz


   1. http://haskell.org/
   2. http://permalink.gmane.org/gmane.comp.lang.haskell.cafe/85781
   3. https://groups.google.com/d/topic/fa.haskell/rURgYMjEZhU/discussion
   4. https://groups.google.com/d/topic/fa.haskell/l-I05W30DWU/discussion
   5. http://permalink.gmane.org/gmane.comp.lang.haskell.cafe/85961
   6. https://groups.google.com/d/topic/fa.haskell/vp2P5w8GbkM/discussion

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