Dust has now mostly settled down on 2048. Yet, in all the deluge of variants and clones that has swept through Hacker News, little has been written about the experience of modifying the game. As I too have jumped on the 2048-modding bandwagon, it’s time to fill that gap, because, as we shall see, the code more than deserves a close look.

Remember Lithium? The x86 assembler written in Clojure, and a simple stripes effect written in it? Well, here’s another take on that effect:

And here is the source code:

Ah, the golden days of childhood’s hackage. Don’t you have fond memories of them?

I got my first PC when I was 10. It was a 486DX2/66 with 4 megs of RAM and a 170 meg HDD; it ran DOS and had lots of things installed on it, notably Turbo Pascal 6. I hacked a lot in it. These were pre-internet days when knowledge was hard to come by, especially for someone living in a small town in Poland; my main sources were the software I had (TP’s online help was of excellent quality), a couple of books, and a popular computing magazine that published articles on programming. From the latter, I learned how to program the VGA: how to enter mode 13h, draw pixels on screen, wait for vertical retrace, manipulate the palette and how to combine these things into neat effects. One of the very first thing I discovered was when you plot every pixel using sum of its coordinates modulo 40 as color, you get a nice-looking diagonal stripes effect. Because of the initially incomprehensible inline assembly snippets appearing all over the place, I eventually learned x86 assembly, too.

tl;dr: Don’t do it. If you really have to, use (#'other-library/private-function args).

A private function in Clojure is one that has been defined using the defn- macro, or equivalently by setting the metadata key :private to true on the var that holds the function. It is normally not allowed in Clojure to call such functions from outside of the namespace where they have been defined. Trying to do so results in an IllegalStateException stating that the var is not public.

I’ve moved to London last September. Like many new Londoners, I have changed accommodation fairly quickly, being already after one removal and with another looming in a couple of months; my current flat was largely unfurnished when I moved in, so I had to buy some basic homeware. I didn’t want to invest much in it, since it’d be only for a few months. Luckily, it is not hard to do that cheaply: many people are moving out and getting rid of their stuff, so quite often you can search for the desired item on Gumtree and find there’s a cheap one a short bike ride away.

This has somehow escaped me: just over a year ago, the Sixth Civil Division of the Lublin-West Regional Court in Lublin, Poland, has opened its online branch. It serves the entire territory of Poland and is competent to recognize lawsuits concerning payment claims. There is basic information available in English. It has proven immensely popular, having processed about two million cases in its first year of operation.

Sequences and iteration

There are a number of motivations for this post. One stems from my extensive exposure to Clojure over the past few years: this was, and still is, my primary programming language for everyday work. Soon, I realized that much of the power of Clojure comes from a sequence abstraction being one of its central concepts, and a standard library that contains many sequence-manipulating functions. It turns out that by combining them it is possible to solve a wide range of problems in a concise, high-level way. In contrast, it pays to think in terms of whole sequences, rather than individual elements.

This is a slightly edited translation of an article I first published on my Polish blog on January 19, 2011. It is meant to target newcomers to Clojure and show how to use Clojure to solve a simple real-life problems.

I’ve recently been developing an iPhone application in my spare time. I’m not going to tell you what it is just yet (I will post a separate entry once I manage to get it into the App Store); for now, let me just say that I’m writing it in JavaScript and HTML5, using [PhoneGap][1] and [jQTouch][2] to give it a native touch.

I keep running into this obstacle every now and then. Consider this example:

> q = []
[]
> for (var i = 0; i < 3; i++)
    q.push(function() { console.log(i); });
> q[0]()
3

I wanted an array of three closures, each printing a different number to the console when called. Instead, each prints 3 (or, rather, whatever the value of the variable i happens to be).