[Haskell] 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.
Announcements
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 (1.2.0.4) 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
Hackage."
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:
http://www.reddit.com/r/haskell/comments/fc4cs/quine_central_because_everyone_needs_to_be_able/
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:
http://www.reddit.com/r/haskell/comments/fbrie/hulk_a_haskell_irc_server/
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:
http://www.reddit.com/r/haskell/comments/fdnjp/status_update_on_code_trac_projects_planet/
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:
http://www.reddit.com/r/haskell/comments/fduxb/all_about_mvars_inside_t5/
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:
http://www.reddit.com/r/haskell/comments/fbgxd/text_a_visual_programming_language_based_on/
Original: http://vimeo.com/19273744
* [SO] Why is GHC so big?
Domain: stackoverflow.com, Score: 21, Comments: 10
On Reddit:
http://www.reddit.com/r/haskell/comments/fczht/so_why_is_ghc_so_big/
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:
http://www.reddit.com/r/haskell/comments/fe63a/haskell_weekly_news_issue_167/
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:
http://www.reddit.com/r/haskell/comments/fcvec/the_f_team_are_hiring_functional_programming_jobs/
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:
http://www.reddit.com/r/haskell/comments/fesjj/recently_uploaded_dsh042_natural_sql_queries/
Original: http://hackage.haskell.org/package/DSH
* Specifying behaviors in a purely functional language
Domain: io7m.com, Score: 16, Comments: 0
On Reddit:
http://www.reddit.com/r/haskell/comments/fdvux/specifying_behaviors_in_a_purely_functional/
Original: http://io7m.com/articles/itefs/
Top StackOverflow Answers
* Why is GHC so large/big?
votes: 29
Read on SO:
http://stackoverflow.com/questions/4858585/why-is-ghc-so-large-big/4867236#4867236
It's a bit silly really. Every library that comes with GHC is provided
in no less than 4 flavours:
static
dynamic
profiled
GHCi
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:
http://stackoverflow.com/questions/4841078/why-map-digittoint-show-is-so-fast/4842308#4842308
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.)
Analysis:
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:
http://stackoverflow.com/questions/4847008/what-justification-for-the-type-of-f-x-f-x-in-haskell-is-there/4847171#4847171
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:
http://stackoverflow.com/questions/4876828/versus-in-haskell/4876900#4876900
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:
http://stackoverflow.com/questions/4867656/starting-a-game-development-in-an-exotic-language-i-am-just-learning-lisp-haske/4868879#4868879
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:
http://stackoverflow.com/questions/4846974/haskell-check-if-int-is-in-a-list-of-ints/4847029#4847029
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:
http://stackoverflow.com/questions/4858585/why-is-ghc-so-large-big
* Starting a game development in an exotic language I am just
learning (Lisp, Haskell, …)
votes: 16, answers: 10
Read on SO:
http://stackoverflow.com/questions/4867656/starting-a-game-development-in-an-exotic-language-i-am-just-learning-lisp-haske
* Why `(map digitToInt) . show` is so fast?
votes: 8, answers: 2
Read on SO:
http://stackoverflow.com/questions/4841078/why-map-digittoint-show-is-so-fast
* Transforming expression given in prefix notation, identifying
common subexpressions and dependencies
votes: 7, answers: 6
Read on SO:
http://stackoverflow.com/questions/4843237/transforming-expression-given-in-prefix-notation-identifying-common-subexpressio
* Practical use of curried functions?
votes: 7, answers: 6
Read on SO:
http://stackoverflow.com/questions/4888480/practical-use-of-curried-functions
About the Haskell Weekly News
You can find an html version of this newsletter at:
http://contemplatecode.blogspot.com/2011/02/haskell-weekly-news-issue-168.html
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
References
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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