I’ve been teaching my eldest daughter to program in Logo over the summer. Brian Harvey has posted PDF files for a set of excellent books on learning to program in Logo on his web site. The Berkeley version of Logo he’s produced is really excellent. It’s not just your typical turtle graphics language; it has arrays, macros, file processing, graphics, etc.

While perusing his site, I came across a tiny Logo program that demonstrates a little of its power. I was curious what it would look like in Ruby, so I ported it, then I had to see what it looked like in JavaScript.

The formatting is a little messed up due to Wordpress, but each of the three choices functions is 4 lines long.

If anyone wants to add other languages, that would be great!

See the sample page for example output.

Logo

to choices :menu [:sofar []]
  if emptyp :menu [print :sofar stop]
  foreach first :menu [(choices butfirst :menu
      sentence :sofar ?)]
end
choices [[small medium large]
  [vanilla [ultra chocolate] lychee [rum raisin] ginger]
  [cone cup]]


UPDATE 9/2/07: Got an even more concise solution from Brian Harvey:

to choices :menu
   foreach crossmap "sentence :menu "print
end

Ruby

def choices menu, sofar=[]
  if menu.empty?: puts sofar.join(' ')
  else menu[0].each {|item| choices(menu[1..-1],
    sofar + [item]) } end
end
choices [['small', 'medium', 'large'],
  ['vanilla', 'ultra chocolate', 'lychee', 'rum raisin', 'ginger'],
  ['cone', 'cup']]


JavaScript

function choices(menu, sofar) {
  if (emptyp(menu)) print(sofar);
  else foreach(menu[0],
   function (x) {
    choices(menu.slice(1), sofar.concat(x)); });
}
choices([['small', 'medium', 'large'],
  ['vanilla', 'ultra chocolate', 'lychee', 'rum raisin','ginger'],
  ['cone', 'cup']], []);


I had to create a few helpers for the JavaScript version:

function emptyp(a) {
  return a.length === 0;
}
function print(list) {
  foreach(list, function (x) { document.write(x + ' '); });
  document.write('<br />');
}
function foreach(arr, f) {
  for (var idx in arr) { f(arr[idx]); }
}


UPDATE: Use <pre> </pre> tags to allow easier formatting of code. Bummer, I just discovered that Wordpress strips the <pre> tags from normal users I’ll go ahead and wrap code with it as they come in, so if your comment looks bad at first, it’ll be cleaned up shortly.

I wrote an article back in May about a way to give half star ratings on Netflix. It had the advantage of working in any browser and not requiring any software installation, but it wasn’t very user friendly.

Since then, I’ve been doing a lot of JavaScript coding, so I thought I’d give Greasemonkey a try. I found a script here to give half-star ratings, but I didn’t care for the hover captions and JSLint pointed out a few issues, so I cleaned it up a little:

Code

// ==UserScript==
// @name Netflix Half Stars
// @description allows half star user ratings on Netflix
// @include http://*netflix.com/*
// ==/UserScript==
// http://userscripts.org/scripts/review/8118
// Modified by Brian Adkins

return 0;
};


Installation

Save the JavaScript code with .user.js extension e.g. netflix_halfstar.user.js and then open that file in Firefox and Greasemonkey should prompt you to install it.

Peter Seibel is working on a book, “Coders at Work”, that will “contain interviews with around sixteen of the most interesting computer programmers alive today”. He has a page that lists 284 programmers, with links to more info on each one, that I think is worth perusing:

284 Coders

Peter is the author of Practical Common Lisp which I highly recommend.

Also see his Google Talk on Common Lisp.

I noticed on Rick DeNatale’s blog that the videos for Ruby Hoedown 2007 are now available.

Here’s an awesome animation by Alan Becker. The youtube version below is a little fuzzier than the original. A lot of work went into this. Thanks to Craig McDowell for passing this along.

Robert Scoble has created three video interviews with Tom Rolander (and a few other folks) dealing with early PC industry history. Who is Tom Rolander? He’s the guy who was flying with Gary Kildall when IBM came calling. The end of the story is that Microsoft got the OS deal with IBM. The video series fills in some of the blanks Aren’t familiar with this story? You should read: Hard Drive

A couple other good tech history books are:
Nerds 2.0.1 and
Dealers of Lightning

Part One

Part Two

Part Three

Here’s a video that explains why using a site such as del.icio.us can be useful. I think they may have failed to mention that you can mark bookmarks as private on del.icio.us, so it’s not necessary to expose your bookmarks to the world. However, in my case, I only mark a small fraction as private.

I’ve been using del.icio.us for quite some time. After I had been using it for a while, I realized that it had been a long time since I bookmarked something in my browser because I had developed a habit of bookmarking in del.icio.us. Most browsers force you into placing a bookmark into a hierarchical, or directory, structure, but on del.icio.us you can assign as many “tags” as you like to a particular bookmark so you can search for things more easily. del.icio.us also allows you to export your bookmarks so you aren’t at the mercy of a proprietary service.

Another thing that is handy is to subscribe to the del.icio.us feeds of your friends to be automatically notified when they bookmark something that may be of interest.

I created Lojic Technologies in 1998. Over the years I have occasionally worked full time at the company while consulting, and at other times I just kept it active to be available in the future. Since I’ve never needed to market myself, I simply threw a web site together as a placeholder.

Now that I’ve been full time with Lojic Technologies since October ‘06 working on several web applications, I’m getting to the point of needing a better web presence, so last Saturday, with some help from my right brained wife, I gave the old site a face lift. It’s still small, and simple, but I think it looks a bit better now.

Besides the cosmetic changes, I also moved from a static site to Ruby on Rails and switched to XHTML 1.0 Strict.

Old Version

New Version www.lojic.com

I’ve also added a link in the sidebar now that the site isn’t an embarrassment. I’m quite pleased with how easy it was to get a Rails app running on Bluehost. I already host this wordpress blog there, so I thought it might be difficult adding a Rails app into the mix without clobbering each other, but it was quite simple (after spending hours researching it )

The site is almost entirely static except for the contact form. I finally arrived at a nice way to host a (mostly) static site with Rails, but I’ll have to blog about that in a later entry.

Here’s Peter Seibel’s “Practical Common Lisp” talk at Google (about an hour):

Google Video Link

This is so easy, you’re gonna love it! Thanks Tyler Pedersen.

Motivation

I’ve been using my laptop more frequently at wifi hotspots. Many web sites I visit encrypt traffic with SSL for authentication, but after that they send traffic in the clear which means the cookies that are used for authentication purposes are sent in the clear, so anyone with a sniffer within range of my laptop could easily intercept the traffic, steal my cookies and impersonate me on the web site. Not good! So, I went looking for a simple solution, and found a great article about using ssh for this purpose. Ya gotta love open source software

Prerequisites

I’ll assume the following:

1. You’ve used ssh before
2. You have access to a remote host running sshd

How To

Issue the following command on your local computer:

ssh -Nf username@hostname.com -D 1080

replace username@hostname.com with the appropriate information. Look at the man page for ssh, or read the article linked above for an explanation of the options.

The next step is to configure Firefox to use the SOCKS proxy you setup with the above command. I’m using Firefox 2.0.0.6 on Ubuntu 7.04 Linux.

Edit | Preferences | Advanced | Settings

Pulls up the following dialog:

Notice how I’ve switched from “Direct connection to the Internet” to “Manual proxy configuration”. I’ve also set the SOCKS Host to be ‘localhost’ and the port to be ‘1080′.

I can now surf and have encrypted traffic between my local computer and the remote host I ssh’d to. The traffic between my remote host and the destination web site will be unencrypted, but hopefully that traffic is harder to sniff without being detected.

At this point, I tested it out and everything worked fine. I then killed my local ssh process and Firefox complained about the connection being reset, so I knew it was in fact sending data over the ssh tunnel.

The final step is optional, but if you want to avoid having the bad guys detect your DNS requests (or possibly redirect them - d’oh!), you can configure Firefox to route DNS requests through the proxy.

1. Type about:config in the Firefox address bar.
2. Look for network.proxy.socks_remote_dns and set the value to true

Is that easy or what? Thanks again Tyler.

I just signed up for the Ruby Hoedown conference. It’s being held here in Raleigh at Red Hat headquarters on August 10 & 11, and the cost is only $100. Speakers include Bruce Tate, Marcel Molina Jr., Ken Auer, Ezra Zygmuntowicz (cool name ), Andrea O. K. Wright, Jay Phillips & Jared Richardson.

I also signed up for the charity workshop on testing techniques put on by Marcel Molina, Jr., Bruce Tate, and Chad Fowler - the donation proceeds for that workshop go to the Food Bank of Central & Eastern NC. It will probably be a smaller group with more interaction.

Should be an interesting and fun time - gain some knowledge, make some contacts. Let me know if you’re also planning on attending.

Some links:

• “Programming Ruby” by Dave Thomas
• “Agile Web Development with Rails” by Thomas & Heinemeier Hansson
• The Ruby Language
• Ruby on Rails
• Mongrel - Ruby web server