Common Lisp in CoCreate Modeling (20 Jun 2009)


This year's European Lisp Symposium in Milan had several slots in the programme for lightning talks - short, high-adrenaline, sometimes impromptu presentations about all things Lisp.

I loved the format because of the wide variety of topics presented. Also, this gave me the unique chance to present to this audience of hardcore Lisp geeks how we are using Common Lisp in our flagship 3D CAD product, CoCreate Modeling. Since I only had a few minutes, all I could do was skim over a few topics, but that's still better than a poke in the eye with C# big grin

Not many in the audience had heard about our project yet, so there were quite a few questions after the presentation. Over all those years, we had lost touch with the Lisp community a bit - so reconnecting to the CL matrix felt just great.


Click on the image to view the presentation. The presentation mentions LOC (lines of code) data; those include test code.

Previous posts on the European Lisp Symposium:

head replacement on Windows (16 Jun 2009)

A co-worker needed to convert a Cygwin-dependent script to something that runs on a bare-bones Windows system. The interesting part of the task was finding a replacement for the good ol' head command-line utility.

Fortunately, this is fairly simple using a few lines of VBScript and the Windows Scripting Host. First, here's the VBScript code:

lines = WScript.Arguments(0)
Do Until WScript.stdin.AtEndOfStream Or lines=0
  WScript.Echo WScript.stdin.ReadLine
  lines = lines-1

This is an extremely stripped-down version of head's original functionality, of course. For example, the code above can only read from standard input, and things like command-line argument validation and error handling are left as an exercise for the reader big grin

Assuming you'd save the above into a file called head.vbs, this is how you can display the first three lines of a text file called someinputfile.txt:

   type someinputfile.txt | cscript /nologo head.vbs 3


Sightrunning in Milan (12 Jun 2009)

Wherever I travel, at least an hour or two of sightrunning is on top of my to-do list.

While I was in Milan for the European Lisp Symposium recently, I had to spend one of the evenings in Milan preparing my presentation on CoCreate Modeling, and so there wasn't much time left to enjoy the city. But I had my running shoes with me, and so I sneaked out of the hotel for two hours in the evening to marvel at sights such as the magnificent dome, the Galleria Vittorio Emanuele, the Parco Sempione and the Arena Civica, Castello Sforzesco, the Scala, Cimitero Monumentale, the Corso Como, the Brera quarter, or Peck (not much of a sight when closed, though).

Sightrunning is just perfect to get a first impression of a city - next time I'm in Milan, I'll already know my way around and what I want to see more of!

Echt einfach, Alter! (09 Jun 2009)

Spruch des Tages, heute morgen in der S-Bahn gehört: "Das ist doch so einfach wie 1*1 = 2!".

European Lisp Symposium: Geeks Galore! (07 Jun 2009)


It's more than a week now that I returned from Milan where I attended this year's European Lisp Symposium, but memories are still fairly fresh. The conferences I go to are usually all pretty nerdy, but this one provided particularly impressive examples of general geekiness.

Not that this came as a surprise. After all, this was a conference about Lisp. Lisp is one of those languages which, as it seems, many love and many others hate, but which leaves few indifferent. And so naturally, the audience at the symposium deeply cared about the language and its underlying value system, and wasn't in Milan just for a few days of company politics or for sightseeing.

For me, this meant:

  • Two days during which I didn't have to explain any of my T-shirts.
  • Not having to hide my symptoms of internet deprivation on the first day of the symposium (when the organizers were still working on wifi access for everyone).
  • Enjoying (uhm...) the complicated protocol dance involved in splitting up a restaurant bill among five or six geeks. This is obviously something that we, as a human subspecies, suck at big grin Special shout-outs go to Jim Newton, Edgar Gonçalves, Alessio Stalla, Francesco Petrogalli and his friend Michele. (Sorry to those whose names I forgot; feel free to refresh my memory.)
  • Meeting Lisp celebrities like Scott McKay (of Symbolics fame)
  • Crashing my hotel room with four other hackers (Attila Lendvai and the amazing crew) who demoed both their Emacs skills and their web framework to me, sometime after midnight. (Special greetings also to Stelian Ionescu.)

How refreshing!

European Lisp Symposium 2009: Keynote (03 Jun 2009)

As promised earlier, here are some more notes from this year's European Lisp Symposium in Milan - this time about Scott McKay's keynote presentation on what he has learned in his years as a Lisp and Dylan programmer at companies like Symbolics, Harlequin, HotDispatch and ITA Software.

Scott joked he might well be the Zelig or Forrest Gump of the Lisp community, after having been around for a long time and making appearances in a number of (unlikely?) places. In amusing anecdotes, he explained some of the key learnings he took away during his career, and what those learnings might mean for the future of Lisp and the Lisp community.

Some notes (from memory, hence most certainly inaccurate):

  • "Any bozo can write code" - this is how David Moon dismissed Scott's attempt to back up one of his designs with code which demonstrated how the design was meant to work.
  • "Total rewrites are good" - Scott was the designer of CLIM, which underwent several major revisions until it finally arrived at a state he was reasonably happy with.
  • "If you cannot describe something in a spec, that's a clue!" - amen, brother!
  • "The Lisp community has a bad habit of building everything themselves"
  • "Immutability is good" (even for single-threaded code)
  • "Ruby on Rails gets it right"; only half-jokingly, he challenged the community to build something like "Lisp on Rails". Later during the symposium, I learned that we already have Lisp on Lines ("LoL" - I'm not kidding you here big grin ).
  • "Java + Eclipse + Maven + XXX + ... is insane!" - and later "J2EE got it spectacularly wrong" big grin
  • He reminded us that the Lisp Machine actually had C and Fortran compilers, and that it was no small feat making sure that compiled C and Fortran programs ran on the system without corrupting everybody else's memory. (I'd be curious to learn more about this.)
  • Lisp code which was developed during Scott's time at HotDispatch was later converted to Java - they ended up in roughly 10x the code size.
  • The QRes system at ITA has 650000 lines of code, and approx. 50 hackers are working on it. Among other things, they have an ORM layer, transactions, and a persistence framework which is "a lot less complicated than Hibernate".
  • Both PLOT and Alloy were mentioned as sources of inspiration.

Scott then went on to develop a list of features which a future version of Lisp, dubbed Uncommon Lisp, should have. That list was pretty long; notable features which I remember were:

  • Should run on a virtual machine
  • Good FFI support very important
  • Support for immutability
  • Concurrency and parallelism support
  • Optional type checking, statically typed interfaces (define-strict-function)
  • "Code as data" not negotiable

Not surprisingly, Clojure was mentioned quite often, both during the keynote and in the subsequent Q&A session. I'm still not quite sure what Scott's position on Clojure really is. To me, most of the points he made seemed to actually back up design decisions in Clojure: For instance, Clojure runs on a VM, reuses the libraries and tools of the underlying platform, connects easily to other languages, makes a decided effort to support concurrency well, and while it breaks with Common Lisp syntax, it is still in the Common Lisp spirit of being a pragmatic implementation of the fundamental Lisp ideas. On the other hand, Scott also criticised some Clojure details (name resolution comes to mind), and seemed uncertain whether to full-heartedly recommend everyone to join the Clojure camp right away.

I think what Scott tried to get across is that a revolutionary approach is both possible and worthwhile for the Lisp community. Revolution, of course, means breaking with the past, and it became obvious during Friday's panel discussion on the future of Common Lisp that not everybody at the symposium felt comfortable with the thought.

PS: Michele Simionato discusses the keynote presentation from a Schemer's point of view.

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