Dean Wampler's Blog

We have extended the deadline for submissions to February 15^th. Get those papers in now! For more information, please see the call for papers.

February 1 is the deadline to submit papers for the IEEE Software special issue on “Multiparadigm Programming”. You can read more about it here.

We also need reviewers for the submissions!

During the exercises for my Scala tutorial at QCon last week, one of the students was mystified by the error message he got when he ran the following (greatly simplified…) script:

  
trait Doubler[T] {
  def double(t: T): T
}
class IntDoubler[Int] extends Doubler[Int] {
  def double(t: Int) = t * 2  
}
  

  
(fragment of ....scala):5: error: value * is not a member of Int
  def double(t: Int) = t * 2  
                          ^
one error found
  

What?! Of course Int has the * member method!!

Well, yes, the final class scala.Int type does have a * method, but that’s not what the word Int means in the declaration of IntDoubler. Because he wrote IntDouble[Int] instead of IntDouble (without a type parameter), he effectively said that IntDouble is still parameterized and the type parameter now has the name Int. The declaration that yields the intended behavior is this:

  
class IntDoubler extends Doubler[Int] {
  def double(t: Int) = t * 2  
}
  

This is a common beginner (and not-so-beginner) mistake. We discussed it in Programming Scala and I posted an enhancement request today for the Scala compiler to provide some “help”. The compiler could disallow any type name that is in scope to be used as a type parameter name, as in our example, or the compiler could at least warn you that you probably didn’t mean for the new type to have a type parameter.

I just completed a search for a new job. In these economic times, finding a job can be daunting, even in the software industry, which has fared better than most. (Today, it was announced that the official unemployment rate in the U.S. is 10.2%, the highest level in 25 years.) A job search can be harder if you're a software developer of a certain age (I turn the big Five-Oh in January).

Despite these obstacles, this was the easiest and most rewarding job search of my career. I had the good fortune to receive several excellent job offers. I regret that I had to turn down all but one of the opportunities. (I start at DRW Holdings after Thanksgiving.)

Read the rest of this entry

I’m teaching an all-day, introductory tutorial on Scala at QCon San Francisco, November 16^th. You can find out more about it at the QConSF web site.

QCon San Francisco is a new conference (this is its second year), but it is already my favorite conference in the US for general coverage of software industry topics. It’s jointly organized by InfoQ and Trifork, the people who produce the highly-regarded JAOO conference in Denmark.

The end of QCon overlaps with the start of RubyConf, so I’ll be attending that one, too, and also the one-day JRubyConf on Sunday, November 22²².

I hope to see you at any or all of those conferences!

I have the pleasure of guest editing, along with Michael Feathers and Tony Clark, a special issue of IEEE Software on Multiparadigm Programming.

Obviously, multiparadigm, a.k.a. polyparadigm, and polyglot programming have been topics I’ve thought a lot about recently (Hence the polyglotprogramming.com web site). Here is the opening paragraph of the CfP:

For most of today’s applications, using one language and one paradigm—for instance, object-oriented programming—is inadequate. Today’s applications are often polyglot, involving multiple languages, and multiparadigm, involving a mixture of deployment directives as well as functional, relational, object-oriented, aspect-oriented, and other paradigms. IEEE Software is soliciting articles for a special issue on multiparadigm programming, or MPP. It will explore MPP technologies, advantages, disadvantages, and applications ranging from embedded and IT systems to the Internet.

You can find out more information about the kinds of articles we are looking for, guidelines for submitters, etc. on the CfP home page. Note that we also welcome people who would be willing to review submissions.

My time at Object Mentor has come to an end. On November 30^th, I start at DRW Trading, where I’ll write all kinds of software for trading applications, some of which is written in Scala, Clojure, etc.

Update: The talk is tonight (Tuesday). The 4th Chicago Area Scala Enthusiasts meeting is Thursday evening.

I’m giving my JavaOne talk at CJUG this Tuesday evening.

The title is Don’t Do This! How Not to Write Java Software. I’ll discuss ten issues I often encounter in Enterprise Java applications, why they are bad, and how to correct them.

Please join me!

We finally got organized; I’m pleased to announce that we’re holding our first meeting at 6:00 on Thursday, Feb. 19, at the Chicago ThoughtWorks offices. Our google group is chicagoscala and more information about the meeting can be found in this message. We hope to see you there!

I’m organizing a group in Chicago for people interested in Scala, called the Chicago Area Scala Enthusiasts (CASE). If you’re interested, join the google group for more information.

I posted an S5-based presentation called The Seductions of Scala (Zip). I'm giving this presentation tonight at CJUG.

To view it, unzip the file and open html/all.html in your browser. Use the arrow keys to navigate or the controls in the lower right-hand corner (visible when you mouse over).

The corresponding code is in the code directory.

Feedback welcome and I hope to see you tonight!

I posted an extended version of the slides from my QCon San Francisco talk, Radical Simplification Through Polyglot and Poly-Paradigm Programming (PDF). The PDF includes some slides I skipped in the actual talk, for time’s sake.

InfoQ.com may offer a video of this talk. Stay tuned.

I’m pleased to announce to Alex Payne (of Twitter fame) and I are writing a book on Scala, a new language for the JVM that combines a succinct syntax, an improved object model and type system, and full support for functional programming. O’Reilly will be the publisher.

I’ve blogged about Scala on the Object Mentor blog.

I was having trouble upgrading Typo, so I moved to Mephisto.

I created a new web site, "Polyglot Programming":http://www.polyglotprogramming.com, that is dedicated to the emerging trend of building applications with multiple languages and multiple "modularity paradigms" (e.g., object-oriented, aspect-oriented, and functional programming). There isn't much there yet. ;) Over time, I hope to add case studies, discussions of different languages, etc.