## Posts

Showing posts from June, 2007

Binary marble adding machine A six bit adding machine, storing state with marbles. (tags: video )

TrimJunction A javascript clone of Ruby on Rails. (tags: rubyonrails javascript )

### Performance with Scala Arrays and Lists

As I continue to tinker with Scala , I was wondering about the performance differences between an Array and List. This post will detail what I've found, but as always YMMV and I could be doing it all wrong. If there's a better (in this case, better == faster) way to do this in Scala, please let me know. My application performs a lot of collection iteration as it combines the values of two collections into a new collection by addition. For instance, I need to combine [1,2] and [3,4] into [4,6] . I wanted to find out if the collections should be an Array or List. Intuition tells me that the Array will perform better, but this is Scala, and Lists reign supreme. So we'll go head to head. For each test, I wanted to write a function that combined the two collections using tail recursion. Test One - Two Lists Into a Third First up, I am adding two lists together while forming a third. One problem here is, due to the way the algorithm is structured, the resulting list is bu

The Sarcastic Gamer: Twisted Trailers: MS Surface Why interact with real humans when you can order your food via a big ass table. Take that, Apple. (tags: humor video )

### Converting Array to List in Scala

Now, this has to have a built-in somewhere in Scala , because it just seems too common. So, how to convert an Array to a List in Scala? Why do I need this? I needed to drop to Java for some functionality, which in this case returns an Array. I wanted to get that Array into a List to practice my functional programming skillz. **Update**: I figured out how to convert Arrays to Lists the Scala way. Turns out it's a piece of cake. val myList = List.fromArray(Array("one", "two", "three")) or val myList = Array("one","two","three").elements.toList The call to elements returns an Iterator , and from there you can convert to a List via toList . Nice. Because my first version wasn't actually tail recursive, what follows is a true tail recursive solution, if I were to implement this by hand. The above, built in mechanism is much better, though. object ArrayUtil { def toList[a](array: Array[a]): List[a] = { d

### That’s a Lot of Actors

As I continue to explore Scala , I wondered just how many (react based) actors I could create in a single JVM. The answer, apparently, is a lot . Before I canceled it, the count was up to 13,500,000 actors. This is on an old Centrino laptop running the Sun 1.6 JVM. I did have to turn up the memory limit a bit, but I never saw memory go above 20MB. Also, I wasn't doing anything inside the Actors. Still, that's enough for me to not have to worry about it. Scala: It's as if Java and Erlang had a baby. Fun stuff.

Mapping Between Java and Scala A helpful mapping between Java and Scala syntax and idioms. (tags: java scala ) First Steps to Scala In this article, you'll follow twelve steps that are designed to help you understand and gain some basic skills in the Scala programming language. (tags: scala )

### QOTD

the future belongs to those who take the present for granted.

Chinese Room Argument [Internet Encyclopedia of Philosophy] In which a thought experiment attempts to discredit A.I.

### RESTifying a Real World J2EE Application

RESTify DayTrader , in which Joe Gregorio converts a real world J2EE application's interface into a REST interface. Perfect example of how to do REST with real life requirements.

Sigma 10-20mm Wide Angle Lens Wide angle lens, recently recommended. (tags: photography )

### A brief history of Consensus, 2PC and Transaction Commit.

A brief history of Consensus, 2PC and Transaction Commit , in which Mark Mc Keown attempts to keep us all in sync with the history of consensus across processes in a distributed system. Excellent read. Thanks Mark!

Some more Rails to lift code examples Converting a Rails application to a Scala on lift application. (tags: scala rubyonrails ) Super Mario Bros: Frustration A hilarious soundtrack to the hardest levels of Super Mario Brothers. Warning, not for virgin ears. (tags: humor video )

### QOTD

We seriously don't know how you IBM keyboard lovers get any work done when it sounds like Optimus Prime pleasuring himself with a jackhammer.

The Best MySpace Page Words to live by. (tags: myspace )