Scheme presentation and more fun with Scala/Swing

June 7, 2009 at 9:50 pm (Scala, Scheme, Week 11) (, , , , )

I gave my lunch & learn presentation on Scheme Friday, and it went pretty well. I found that I had forgotten to correct one of my slide mistakes, but aside from that I felt good about it. I went through the basics of Scheme/Lisp syntax and talked through some examples, and then finished up with the prime factors kata in Scheme. It went almost twice as long as I’d expected, since we stopped several times to discuss and answer questions. I took suggestions on the kata as well, which also slowed things down, but I felt like it was a better way to teach the process of refactoring to an inner recursive function (in place of what would be a loop in an imperative language). Everyone seemed interested and I got some great advice afterwards. The biggest things were that I didn’t always stand up (sometimes camping out in a chair) and that I kind of half-heartedly slapped a name on the presentation (“Scheme for Rubyists”) with only a few references to Ruby (where I could have had comparable Ruby examples for all my Scheme code).

Here are my [corrected] slides, if you want to get the basic gist (unfortunately, the formatting doesn’t translate perfectly to ppt file format – I used OpenOffice): Scheme Presentation

Friday afternoon and this weekend, I got a basic working version of Tic-Tac-Toe using Swing in Scala. I still have plenty to do: just as before, with Java Swing, I was basically spiking to learn the framework, and so there are some GUI tests missing. For now, I’ve put in TODO’s for implementation code I don’t have tests for; tomorrow I’ll start commenting out those pieces of code and driving them test-first. I feel good about my board and player classes; Friday I implemented some in-memory caching to speed up the computer player’s board-scoring computation. I still need to do some thinking about the technical article part of my apprenticeship challenges. I’m leaning towards something on functional programming, perhaps a few refactorings from imperative code to functional.

Advertisements

Permalink 2 Comments

Week 5, Weekend

April 26, 2009 at 8:20 pm (Reading, Watching, Week 5) (, , , , , , , )

I’m constantly amazed by the amount of information available online to help people improve and learn. To my wife’s chagrin, I spent several hours watching video lectures by Hal Abelson and Gerald Jay Sussman (from a 1986 course presentation at Hewlett Packard) and by Douglas Crockford (at Yahoo, I believe).

These aren’t directly related to my assignments for the apprenticeship, but I’m learning a lot. The Abelson/Sussman lectures (also on Google Video) are based on their book, The Structure and Interpretation of Computer Programs (SICP), which I understand was the introductory course at MIT for many years. I recommend the 256k mp4 versions if you’re downloading – the 64k are too hard to make out, and the high-res ones are huge! The language, Scheme, has got some pretty cool features, but to be blunt, the parentheses are pretty ugly. The really interesting part of this language, so far, is that functions are first-class objects, which can be saved into variables, passed into other functions, etc. This isn’t a completely foreign concept to me, as Ruby has closures like Procs and lambdas, but I think it’s the area of Ruby where I feel the least comfortable. Another pretty crazy thing is the way control structures like loops must work: recursion (a function might call itself with a modified index). I feel like I’d have had an easier time beginning to understand the minimax algorithm if I’d watched these videos first – the tree structure in particular was clearly explained, in one example, as it related to recursion.

I’d seen Caleb Cornman‘s tweets about the Crockford videos (they’re also available for download from the YUI Theater site), and realized (for the umpteenth time) that even though I’ve written a decent amount of Javascript in my day, I know basically jack about how the language works. I’ve generally just let the Rails helpers, JQuery, or Prototype to do the dirty work for me, hacking in the rest as needed. So that can work, as it does for many others, but trust me when I say that you don’t want to be debugging ugly Javascript. I’m a little weirded out that I just happened to be learning about lambdas and Lisp, and Crockford mentions several times that how Javascript is the first language with lambdas to really hit the mainstream. Javascript has no concept of classes, only objects! I’m surprised, but intrigued to learn a lot more about the subject. Currently debating whether to start with Crockford’s Javascript: The Good Parts (recommended highly by Jim Suchy) and David Flanagan’s Javascript: The Definitive Guide (the only book Crockford recommended other than his own). The local library has the 4th edition of the Flanagan book – I wonder how much has changed in the most recent (5th) edition… Anyone familiar with these and have advice?

I spent some time during and after each of the videos fooling around with practicing Scheme and Javascript, in Emacs and Firebug (a Firefox add-on), respectively. I’m starting to get the hang of Emacs, which is encouraging. I’d need to do a lot more reading and practicing to get as good with it as I am with Vim, but I feel like I should at least have a rudimentary knowledge of how to get around in Emacs, since it’s one of the most-used editors on Unix machines (and has such strong Lisp integration).

I also did a lot of reading, from Refactoring by Martin Fowler et al., and a book I’m reviewing for the Pragmatic Programmers. I won’t say much about the review book, but it’s very good so far, and I think it’ll turn out wonderfully. They were looking for someone who wasn’t an expert, and as I told Micah, that’s me!

Refactoring is so much more readable than I’d imagined. I had always thought of it in the same category as the Gang of Four Design Patterns book, which I flipped through once at a bookstore and found it to be far beyond my understanding. I think at this point it’d be easier, but Refactoring is extremely clear and easy to read. I wish I’d read it sooner, because it describes a lot of the things I’ve done to clean up my Tic-Tac-Toe (and to make changes to it as they came up). The automated tools in IntelliJ made the process easier, of course, but I’m also discovering that some of my bigger changes could have been made much easier by applying the steps in the refactorings catalog.

It’s always a good sign when you’re excited to get back to work and do some coding, but I’m wondering if I should be doing more actual coding at home. I may get into some Limelight Tic-Tac-Toe tonight – I think that things should fall into place more quickly now that at least some of the game logic is hooked up between Java and Ruby.

Permalink 2 Comments