Moving to Atom 1.0
Thanks to a patch by Sebastian Vuorinen,
Nukumi2 now supports Atom
1.0 feeds. I changed the feeds of chris
blogs and
Anarchaia to Atom 1.0. If your feed reader
can’t cope with it, please get a different one, use the RSS2 feed, or
use the old Atom 0.3 feeds which have the extension .atom0.3. I
don’t want to keep them around for too long. (I’ll check the logs for
this.)
If you want to publish Atom 1.0 too, darcs pull now.
Thanks a lot, Sebastian.
NP: Bob Dylan—It Takes A Lot To Laugh, It Takes A Train To Cry
The Rightyear parsing library
Last week, I ported Monads in
Perl to Ruby just
for fun and learning. It’s amazing how one can port code without
really understanding it, for programming languages the Chinese Room
Argument certainly
works.
When I converted all the code from the page, I reread some of my
Haskell papers and got hooked by Yet Another Haskell
Tutorial which has a good chapter
on monads and their use. It also uses monads to build a
parser combinator, which
is an popular approach to parse in Haskell and other functional languages.
Rather quickly I had a direct port of something akin to
Parsec. I needed a name and
Martin DeMello proposed “rightyear”, the
japanese pronunciation of lightyear, which is about a third parsec, of
course. For testing, I wrote a parser to read something like a very
primitive kind of XML. This is an easy example of a context-sensitive free
grammar in Parsec:
xml = do{ name <- openTag
; content <- many xml
; endTag name
; return (Node name content) }
<|> xmlText
And that’s the complete Rightyear parser:
class ParseXML < Parser
def parse_xml
parsing { xml.passthru eof }.run
end
def xml
choice open_tag.bind { |name|
many(xml).bind { |content|
end_tag(name).bind { ret [name, content] }
}
}, text
end
def open_tag
char(?<) >> one_or_more(char_matching { |c| c.chr =~ /\w/ }).bind { |t|
char(?>).bindret t.join
}
end
def end_tag(t)
char(?<) >> char(?/) >> string(t) >> char(?>)
end
def text
one_or_more(char_matching { |c| c.chr =~ /\w/ }).bind { |s| ret s.join }
end
end
As you can see, Haskell’s do-notation doesn’t map very well to Ruby;
it’s rather cumbersome to write. After a bit of twiddling, I found
out that I didn’t actually need monads at all; instead I can use
exceptions or throw/catch to trackback. Now, the parser looks like
this:
class ParseXML < Rightyear::Parser
def xml
choice seq {
name = open_tag
content = many { xml }
end_tag name
[name, content]
},
seq { text }
end
def parse_xml
v = xml; eof; v
end
def open_tag
char(?<)
t = text
char(?>)
t
end
def end_tag(t)
char(?<); char(?/); string(t); char(?>)
end
def text
one_or_more { char_matching { |c| c.chr =~ /\w/ }.chr }.join
end
end
Which is a lot better for the eyes, no? It’s actually
straight-forward to write parsers in this, but you need to ensure you
don’t have left-recursion in your grammar, because that borks parser
combinators in general. The big advantage over
Bison and similar
tools is that you easily can mix in your own code and can parse full
LL(∞).
Unfortunately, the trackback via exceptions still is rather slow, it
takes about 6 seconds to parse "1+#{'1+' * 6000}1" on my iBook. So
consider this as an academical exercise for now; I learned a lot about
monads and Haskell and how it sucks when you rewrite it in non-Haskell
languages. :-)
People have been doing this in Tcl/Tk and
Python, and even
C
too.
Further reading: Fast, Error Correcting Parser Combinators: A Short
Tutorial (PDF)
by S. Doaitse Swierstra and Pablo R. Azero Alcocer.
NP: Bob Dylan—Tonight I’ll Be Staying Here with You
Heidenröslein, Muselmänner und Tomatografie
Trotz Kaugummi- und
Rauchverbot
und anfangendem Klausurenstress bleibt auch bei uns der Spaß nicht zu kurz:
What do you think?
— Nix!
Was? Die Muselmänner sind in Deutschland?
Lieber Heidenröslein als Christrose.
Manga Moralia
Ich weiss schon wie’s geht, ich wollte nur den Spruch
loswerden…
Mir ist kalt!
— Jammere nicht, so schläfst du schon nicht
ein!
[Kriegsveteranen unter den Lehrern?]
[Lehrer packt US-Flagge aus. Schüler:] Anzünden!
Wir sind in der 5. Klasse, und ich hab immernoch das geistige Niveau.
Tomatografie
Werwolf & Waswolf
NP: Bob Dylan—Sarah Jane
Euruko 2005 -- Day two
Continued from day one.
On the second and final day of Euruko 2005, the
European Ruby Conference began at about ten o’clock.
Steve Purcell, Mocking Objects with RMock
Steve Purcell, who by the way was the first speaker that said he is a
Rails user, presented an implementation of mock objects done by him.
Mock objects are a technique for writing better unit tests; they
provide fake versions of other systems. These fake versions now can
be made to produce the test scenarios you want.
He said that by using mock objects, one can trade “reality” for
control over the test environment, as testing classes can happen in
isolation using fake collaborators. He emphasized that mock objects
are not just stubs. After this, he demonstrated how to use RMock by
implementing tests for an imaginary BurglarAlarm—with lots of
feedback from the audience.
Update: RMock is now known as Mockr
and can be found at sanityinc.com.
Michael Neumann, Ruby and DSLs
The next one in order was Michael Neumann, who presented various
Domain Specific Languages that he developed in Ruby.
Michael implemented a DSL for dealing with formal systems (think logic
terms) in Ruby, which gets very usable due to heavy
operator-overloading. He also wrote a script to automatically typeset
those terms using lout. An example of what this DSL looked like:
V::x { P(:x, :y) } >= E::y { Q(:y) & V::Z(:x) }
Michael also wrote a high-level macro assembler for MIPS and an interface
to the Ploticus visualization package in Ruby.
Of course, he showed the programmatic HTML generation made for
Wee which is based on “brushes” that are outputted on generation of
the next one. This allows for a very convenient syntax.
Then, he explained how to implement DSLs in Ruby and which language
features help with this: instance_eval, undef_method,
method_missing and const_missing. Interestingly, he also
mentioned scoped globals, which are pretty much the same I
presented as “dynamic variables” the day before. :-)
Sven Koehler and Armin Roehrl, Futurometer
First, Sven Koehler told us about the state of financial tools for
stock market analysis. He claimed these programs are stagnating, and
went on by outlining a system, dubbed Futurometer, that they have been
writing for quite some time, which can help with that. It is supposed to
be a kind of “google for the financial market”.
He compared the patterns in earthquakes and stock market crashes and
told us how linking graphs of different areas could help predicting
stock markets.
The Futurometer web application counts and graphs the occurrence of
certain words, like “bird flu” or “al kaida” on Google
News.
After this, Armin continued the talk and showed us some slides that
analyzed the grounding of Swiss Air. He explained how statistical
techniques like EVT (Extreme Value
Theory)
can help with investing. He said schoolbook statistics usually are 20
years behind from what the current methods of statistics are.
This talk sparked a long and very interesting discussion on economics
and globalization. After the discussion, we tried to estimate the
amount of energy that could be saved if everyone used Ruby instead of
Java. :-P
Marcus Barchfeld, Eclipse’s Ruby Plugin
After the discussion, Marcus Barchfeld did a live demonstration of
Eclipse’s Ruby plugin, RDT. I
can’t say much about this either.
Michael Neumann, We.eXplained
In his second Wee talk, Michael Neumann explained the inner workings
of Wee.
He compared Wee to a GUI that runs over the net and explained how Wee
is component oriented and which parts are inspired by Seaside2.
Then, he went on by talking about decorations and their implementation
and how URLs in Wee are mapped.
A full demonstration of a Wee request cycle and when one should or
shouldn’t use Wee concluded his presentation.
Johannes Pirkl, Nitro, Wee, Og and Glue
After this, Johannes Pirkl demonstrated how Nitro, Wee, Og and Glue
can work together. He showed quite a lot of code and some of the
techniques behind Nitro and Og.
Robert Kuzelj, Teclarative, a DSL for Testing
The last talk of Euruko 2005 was by Robert Kuzelj, who presented a
more declarative unit testing framework he actually wrote in five
hours during the conference. :-)
He argued a bit against Test::Unit and spoke about how syntax
matters because syntax expresses intent.
Advantages of Teclarative are easy configuration, activation, and
grouping of tests. Also, there is per-test-configurable setup and
teardown. Furthermore, Teclarative allows for more flexible test
naming (any string) and smooth creation of huge suites.
Robert finished his presentation by demonstrating how to use it.
Conclusion
Stefan Schmiedl quickly summarized Euruko 2005 and thanked everyone
that helped and made it possible. He gave an outlook on next year,
which will be interesting, as the number of attendees doubled this
year. It peaked at about forty persons, even though RubyConf
2005 was talking place at the same weekend.
When the conference is going to get bigger and bigger, there will be a
lot more planning involved, and the space at Sulzer GmbH won’t be
enough anymore. I’m sure they’ll find a solution for this, though.
All in all, I only can say that Euruko 2005 was a huge success from my
point of view, and I think everyone that attended will agree.
See you all on Euruko 2006!
NP: Blood Ruby—Remains of the Day
Euruko 2005 -- Day one
This is the first part of
two
blog posts about Euruko 2005, the European Ruby
Conference that took place on October 15th and 16th 2005 in Munich.
On Friday evening, the guys that already were in Munich met at
“Ristorante Ai catelli”, which is an excellent Italian restaurant in the
night-active heart of Munich. We probably talked (and drank!) there
until half past twelve.
On Saturday morning, after everyone had introduced himself, the talks
were collected in an “agile” way and we decided the order of
presentation.
These were the talks of Saturday in chronological order:
Kingsley Hendrickse: Agile Testing with rubySelenium
Kingsley first gave an quick overview of the agile process
and acceptance test driven development for the people that didn’t
know about TDD yet. He outlined the use of stories, how to practice
test-first and that stories are accepted when all tests pass.
Then, he explained the testing phases used by him,
iterative testing, system integration testing, regression testing,
performance testing and, finally, wider user acceptance testing.
He told that his web testing framework, which is by the way called
rubySelenium because of
the competitive, commercial, system Mercury, was especially good for
test-first development. Also, it is easy to use for people of
different levels of ability and, unlike Mercury, free of licensing
restrictions. It is available as a gem.
He also explained that they use exploratory testing, which is
essentially unscripted testing performed by humans to find potential
bugs that were not considered during design and development. However,
bugs get scripted and added to the test-suite when they are found.
According to him, agile testing covers three parts of testing:
development interface testing, quality assurance and system
integration testing.
The main benefits of the agile process are to have fully automated
regression tests, get immediate feedback about bugs and the state of
development in general, create tests with minimal training and feeding
back (production) bug fixes. In the end, you have a far higher
confidence in your quality.
All in all, agile development helps building the application around
the customer’s criteria, have bugs ironed out by constant feedback,
being able to better estimate due to constant feedback and allow for
early integration tests with mock interfaces.
Kingsley finished his talk with an demonstration of rubySelenium,
which probably is best described as a kind of DSL for declaring
assumptions about websites.
Armin Roehrl, Watir — Web Application Testing in Ruby
Armin Roehrl continued demonstrating how to test web applications,
this time using Watir, which is
essentially a library to drive Internet Explorer to make it look like
a user is using it. Watir makes this possible by providing full
access to the DOM of an Internet Explorer instance over COM. The
benefit of this is that Watir allows for having control structure in
Ruby, whereas Selenium is purely declarative.
Paul Battley, Using Unicode in Ruby
Next, Paul Battley had a talk on how to make use of Unicode in Ruby.
After an quick introduction of Unicode, it’s pros and cons and how it
is encoded (UCS-4, UTF-32, UCS-2, UTF-16, UTF-8, not to forget the
thing with endianess) he elaborated on the advantages of UTF-8.
Then, he also informed us about the “banana skins” of Unicode,
according to him: the Byte-order Mark, differing operating system
capatibilities, confusion about byte/char/codepoint/glyph, sorting and
casing Unicode, normalization and Microsoft—which tends to
handle some Unicode issues in a different way.
After this, he explained how to be careful in Ruby as Strings only
are arrays-of-bytes, so, for example, there is no reliable [] and
the length is returned in bytes. He also explained how to use Iconv
and showed a nice trick with //IGNORE that I didn’t knew about Iconv
yet. He taught the audience a lot of tips and tricks on how to deal
with Unicode.
Paul ended his talk by looking at the future of Unicode processing in
Ruby. There probably will be bindings to ICU, a library to deal with
many Unicode issues, and Oniguruma, the future Ruby regular expression
library with better Unicode support. Last but not the least, he also
showed how to do mischief with Unicode.
Sven Koehler, Introduction to Wee
Sven Koehler now did the first of IIRC three talks on Wee, a web
application framework that aims to be a clone of Seaside, which is
written in Smalltalk. Wee is continuation based and features
convenient HTML generation by code. He says Wee can be described as
“dynamics on the server side” and contrasted it with AJAX, which can
be used to implement this dynamicity on the client side.
He went on with demonstrating basic Wee usage.
Rob McKinnon, Ruby Editor Plugin
The next demonstration was by Rob McKinnon, which presented his JEdit
Ruby Editor Plugin. I can’t say too much
about this, actually. :-P
Sven Koehler, Monitoring Enterprise Applications
After Rob, Sven had his second talk today which was about enterprise
environments and how to deal with them.
Sven is using Ruby and Wee at BMW to get an better overview about a
really complex legacy system they run there and quickly demonstrated
how he did this.
They have two systems there, a procurement application (which can be
described in terms of User, Requisition, Catalogue, Account, Order
that are all from different systems) and a ticket application which is
like Bugzilla. The probably most amusing thing was that some old
applications do kind of “RPC over SQL” for inter-process
communication; that is, they insert a record into a database and a
different process looks for new entries, does some calculation and
inserts another record with the result. What a hack. :-)
Christian Neukirchen, Dynamic Scope and Context-oriented Programming
The last talk on Saturday was mine about Dynamic Scope and
Context-oriented
Programming.
I have put the
slides
and accompanying code
online, so it’s probably best you see for yourself. :-)
All I can say is that people probably really liked it, at least quite
a few people told me how impressive they thought it was.
Dinner at Aumeister
After my talk, we all walked to the Aumeister beer garden and
continued discussions there about various things. Ain’t nothing
better than to hack code after dinner. :-) I, for one, had an
interesting conversation with Stefan Schmiedl on various programming
languages. Especially Forth was quite popular there, almost everyone
talked about it somehow… how will this influence the future of Ruby?
To be continued on day two.
NP: Rolling Stones—Ruby Tuesday
Off to Euruko 2005
Right now, I’m really busy packing my things together for Euruko
2005, the European Ruby Conference. I’ll be
talking about “Dynamic Scope and Context-oriented Programming” there.
Slides to appear here.
I’ll try to blog about EuRuKo, but since I only have net access at the
conf (hopefully!), updates will appear on the next day soonest.
Looking forward to meet everybody…
Also, drop by if you can!
NP: KT Tunstall—Heal Over
Paradoxien des darwinistischen Kapitalismus
Eigentlich scheint es alles ja ganz einfach: In meiner Heimatstadt
Biberach gab es zwei Kinos, beide hatten drei Säle und durch Listen
wurde garantiert, dass beide Kinos stets verschiedene Filme zeigten.
Beide Kinos hatten eine lange Vergangenheit, das eine Kino,
“Filmtheater” genannt (für diesen tollen Namen würde vor langer Zeit
übrigens mal ein Wettbewerb ausgeschrieben…) war immer etwas
günstiger, vorallem für Schüler. Das andere, das “Ringtheater”, war
etwas teurer und hatte nur einen großen Saal, die anderen waren
ziemlich klein. Der Betreiber hat allerdings zwei weitere Kinos in
der näheren Gegend.
Da die Filme jedoch fair verteilt wurden, wurden beide Kinos wohl
gleich stark frequentiert. Um das in drastischen, kapitalistischen
Worten auszudrücken: Stillstand. Unentschieden.
Ergo beschloß der Betreiber des Filmtheaters, eine riesige Summe (man
redet von vier Millionen Euro) aufzuwenden und das Kino total
auszubauen. Dazu musste es allerdings für ein halbes Jahr schließen.
In dieser Zeit hatte das Ringtheater praktisch das Film-Monopol in
Biberach, und machte wohl ungeahnten Umsatz.
Das Filmtheater ist inzwischen wieder geöffnet, heisst nun allerdings
“Sternenpalast” und ist mit acht Kinosälen das größte Kino
Oberschwabens – laut eigenen Angaben. Es bietet sehr bequeme Sitze,
riesige Leinwände und modernste Soundtechnik.
Desweiteren hat es attraktive Preise; montags zahlen alle den
Einheitspreis von 4,50€, donnerstags ebenso, wenn man weiblich ist.
Interessanterweise war der Sternenpalast nach der Eröffnung immernoch
billiger als das Ringtheater davor.
Da der neue Sternenpalast nun ja auch über acht Säle verfügt, ist es
ihm möglich, sämtliche Filme zu zeigen, die momentan im Vertrieb sind.
Nach etwa zwei Wochen senkte das Ringtheater die Preise so, dass sie
bis auf Montag und Donnerstag günstiger als der Sternenpalast sind.
Das war wohl vor einem Vierteljahr.
Letzte Woche hat das Ringtheater dicht gemacht.
Darwinistisch gesehen ist das klar; wer würde denn nicht in ein
tolles, günstiges Kino gehen, in dem ein interessanter Film kommt,
wenn es sonst nur in ein altes, relativ teures Kino mit beschränktem
Angebot gibt? Keiner natürlich.
Was aber auch nur die wenigsten bedenken ist, dass nun, da das
Ringtheater geschlossen hat, der Sternenpalast beliebig die Preise
erhöhen kann, da ja in 20 Kilometer Umkreis keine Konkurrenz zu finden
ist.
Was tut der Kapitalist? Besser: Was hätte er tun können?
Ist es kapitalistisch korrekt, ein schlechtes Angebot anzunehmen, um
ein gutes zu erhalten? Ist das mit Darwinismus vereinbar? Sind
Kapitalismus und Darwinismus überhaupt vereinbar? Wie sähe die Welt
wohl aus, wenn Tiere aufeinander Rücksicht nähmen, um sich “besser”
fortzupflanzen statt auszulöschen? Was ist “besser” überhaupt?
Ich fragte einen Freund, was der sorgende Kinobesucher denn tun kann
wenn der Sternenpalast die Preise erhöht; er meinte, “Dann fahren wir
eben nach Ulm”. Deutscher Fatalismus.
Glücklicherweise ist das ganze Equipment des Ringtheaters noch da, der
Betreiber kann wohl auch von den Einnahmen aus seinen beiden anderen
Kinos leben… und man müsste darauf hoffen, dass er sein Totkapital
nicht aktiviert.
NP: Antony and the Johnsons—You Are My Sister
Neues aus China
Diese SMS während der heutigen Geschichtsstunde, die ich von Valentin,
der gerade mit unserem Rektor, ein paar Lehrern und anderen
Schulkameraden in China ist, erhalten habe, könnte auch andere
interessieren:
Und, geschichte geil?
(wir fliegen jetzt nach peking (freibier)) :)
gruß valle
Sauerei, oder?
Desweiteren hat die Weberberg
Bergzeitung endlich mal einen
Schreibstil drauf, der mir doch sehr gefällt:
Am kommenden Mittwoch, 5. Oktober, findet in Biberach wieder der
Michaeli-Markt statt. Wieder Gelegenheit, neue Gemüsehobel,
Wunderputzmittel und Socken zu kaufen. Und Leute zu bestaunen, wie
sie Hieronymus Bosch nicht besser hätte erfinden können.
Mehr kann man dazu wirklich nicht sagen…
NP: Juliette & the Licks—I Never Got to Tell You What I Wanted to
The Samsung YP-U1X
Today I bought an MP3 player by Samsung, the
YP-U1X,
primarily because it not only plays MP3, but also Ogg
Vorbis (They are so humble, they don’t even
mention that outside the technical specification; it’s the killer
argument!). Since a significant part of my music collection is in
Ogg, this was an essential requirement to me. Also, it was pretty
cheap—77€ for 512MB flash.
Overall, I’m very pleased with it. The display is sharp and has a
good backlight, the design is pleasing (okay, it’s not as nice as a
Nano, but not as butt-ugly as some random no-name player). Last but
not the least, the usability is fairly good, although this is no
reason not to ship with a printed version of the manual, Samsung!
Unfortunately, it has no direct encoding to MP3 while recording, but I
can live with that.
There is only one thing that bugs me, and it’s a rub a lot of MP3
players have. It’s about sorting the songs and the order they are
played in. My music is arranged like
~/Music/Artist/Album/Song. The
name doesn’t contain the track number, mostly because I use playlists
when I use XMMS and iTunes sorts the songs on its own anyway. I
really don’t understand why the players can’t do that too.
Anyway, Ruby to the rescue. The script
grok_order.rb takes directories as
parameters and makes a list of all music files contained in them.
Then, it orders them by their album and track and finally prefixes the
files with nnnn- to enforce the order for alphabetically-sorted
players.
Therefore, I just need to run
ruby grok_order.rb /Volumes/YP-U1X
and the tracks are in the order they appear on the albums. Enjoy.
NP: Bob Dylan—Hard Times in New York Town
