Ask HN: The most fun and beautiful code you know of?

Funny seeing this, because I was at my local Borders earlier and decided to give that Beautiful Code book a shot. I've seen it on the shelf for quite a while, but those books don't tend to turn my crank, so to speak, so I had never before really considered it.<p>I only read the first and the third essay, but I must say, wow!<p>The third essay, for instance, takes a simple 12 line implementation of quicksort in C (which is already quite beautiful), and through a series of well explained transformations, arrives at a four line proof (as in, it's C code that is equivalent to the recurrence relation, and eventually the summation, we all solved in our CS classes) of the average case complexity (~1.4nlgn comparisons) of the quicksort he started with.<p>That is what I would consider "nightstand" code, or at least a nightstand essay about code. It was actually entertaining, to the point that you don't realize you are solving a recurrence relation in C form until the end, when the parallel becomes obvious.<p>I only had a chance to skim the other topics, but I'm actually considering buying it, because it really was a blast to read.

UTF-8 encoding in 6 lines, from ezxml:<p><pre><code> if (c &#60; 0x80) *(s++) = c; // US-ASCII subset else { // multi-byte UTF-8 sequence for (b = 0, d = c; d; d /= 2) b++; // number of bits in c b = (b - 2) / 5; // number of bytes in payload *(s++) = (0xFF &#60;&#60; (7 - b)) | (c &#62;&#62; (6 * b)); // head while (b) *(s++) = 0x80 | ((c &#62;&#62; (6 * --b)) &#38; 0x3F); // payload }</code></pre>

The UNIX v6 kernel (Lions book). Every page brims with the excellent, <i>hard</i> tradeoffs required to shoehorn what we'd recognize as a modern system onto a 128K 16-bit machine.

My own code...<p>(Not because it's perfect and beautiful, but just because I wrote it and understand it.)

Duff's device. It opened up my eyes for the beauty of C and insanity of compilers: <a href="http://en.wikipedia.org/wiki/Duffs_device" rel="nofollow">http://en.wikipedia.org/wiki/Duffs_device</a>

Usually I find API documentation more inspiring than actual code. It's higher-bandwidth. That said:<p>- Some bits of <i>On Lisp</i><p>- Haskell's SYB and Parsec libraries<p>- MINIX (2; have yet to play with 3)

Solutions in Programming Pearls. Each solution is iteratively improved with the proper reasoning.<p><a href="http://www.amazon.com/Programming-Pearls-2nd-ACM-Press/dp/0201657880" rel="nofollow">http://www.amazon.com/Programming-Pearls-2nd-ACM-Press/dp/02...</a>

Anything that:<p>* Doesn't repeat itself. This includes languages which involve marking out blocks of code once for the interpreter and the second time for humans.<p>* Is short, because it doesn't reinvent common modules, and modularizes out general logic.<p>* Uses descriptive names, including using dictionary keys rather than vague list element numbers. A good test is if you can show the code to someone who doesn't work in computing and have them understand it. ZS had a talk on this where he showed lawyers SOx code and received feedback on the rules, changes to the order, etc.<p>* Uses tree structures for tree structured data (eg, etrees and xpath) rather than treating such data as strings and using RegExs.<p>* Has docstrings.

Shakespeare. It exists. Seriously. It's as beautiful as Shakespeare, but not very fun, sadly.<p><a href="http://en.wikipedia.org/wiki/Shakespeare_(programming_language)" rel="nofollow">http://en.wikipedia.org/wiki/Shakespeare_(programming_langua...</a>

The art of computer programming.<p>Not because it's direct computer code, but because when I'm reading it past code i've written starts swirling in my head. Sort of one of those "ahhh fantastic" moments.

/* fun only <i>/ #const HellIsAHotAndFieryPlace=1 while (HellIsAHotAndFieryPlace) printf("The end is near\n") ;<p>/</i> yes it did make me laugh when I read it in Atari St user */

Very few people will get this reference, but when I had access I used to read the genweb3 code. It's like a whodunnit because there are no comments. :)

pseudocode all throughout cormen... I appreciate industrial code the same way I appreciate a ferrari - without looking at the engine

Shakespeare. It exists. Seriously. It's as beautiful as Shakespeare, but not very fun, sadly.<p><a href="http://en.wikipedia.org/wiki/Shakespeare_(programming_language)" rel="nofollow">http://en.wikipedia.org/wiki/Shakespeare_(programming_langua...</a>

<a href="http://lxr.linux.no" rel="nofollow">http://lxr.linux.no</a>

c99shell. It's a PHP trojan horse of sorts written by Russian hackers. Beautiful, rare, dangerous and awesome.

OpenBSD, Django and code written by Niels Provos.

Google.