Today, the hash function has selected The Practice of Programming by Brian Kernighan and Rob Pike. On my shelf you’ll probably find a couple dozen reference books that are written about various programming languages. This book is one of a smaller handful that literally talks about programming: how to write clear, general, reliable programs that are portable, perform well, and are an actual pleasure to read. I’ve great respect for Kernighan and Pike: their older book The Unix Programming Environment was one of my principle references on Unix when I was still a fledgling acolyte into the ways of Unix. More than just being informational, that book was inspirational. It showed that the Unix environment gave the programmers power to implement powerful new things using powerful mechanisms and simple techniques. It conveyed the appropriate mindset to make maximal use of the operating system facilities.

The Practice of Programming fufills a similar role, but instead of focusing on operating facilities, it focuses on programming languages. It must be confessed that while it does have brief forays into C++ and Java, it’s a book that includes mostly C code. For this, and its concentration on “programming in the small” rather than larger, group based development techniques, it has been labelled as “dated” or “old-fashioned”. I think this is like criticizing a guy who can cut a beautiful dovetail joint by hand for not using glue and nails. To Kernighan and Pike, good programs are actually pleasurable to read, and the vast majority of code doesn’t pass the test, and the larger the program and the greater the number of programmers, the less likely it seems to pass this simple test of aesthetics. Nevertheless, I would submit that there are lessons here for every programmer. The good thing is that each point of style is illustrated with actual code designed to convey the lesson. Thus, you learn what good code looks like via the Socratic Method: by asking questions about code, and stimulating thought and critical thinking about code in all its aspects: from design to implementation to testing and debugging.

If you don’t know C, you might need another book to get off the ground, but The Practice of Programming is a book with lasting value on my shelf.

Addendum: Rob Pike has his own (and in some circumstances) controversial view about what beautiful programs look like. You can see some hint of them in his work on the Go language at Google. One of the explicit design goals for Go was to make programming more fun and more expressive. I think it’s a fascinating new language and points out a bit how programming has been led astray in recent years. If you want a taste of what Go is like, check out his Google Talk:

Today’s book is Mathematical Recreations by Maurice Kraitchik. As might be evident to long time readers of my blog, I have a lasting interest in what might be called “recreational mathematics”. This is a particularly challenging thing to define, since so much of what we might consider recreational mathematics unveils deep and mysterious things within mathematics. At the Hackers conference I just attended, we paid tribute to the greatest popularizer of recreational mathematics: Martin Gardner. I opined that he was basically invented recreational math, which met (somewhat surprisingly, and I’d still say incorrectly) with some opposition. One of the counterexamples was Maurice Kraitchik.

Many so-called recreational mathematics books are little more than shallowly described algebra problems. Kraitchik’s Mathematical Recreations rises significantly above that. First published in 1942, it includes a wide variety of topics, including gambling, games, magic squares, number theory, geometry, cryptarithmetic, and permutations. You’ll see some things which you’ve seen before, but probably a few gems that haven’t seen wide coverage. For instance, I found this problem to be fairly nice, from page 140.

A man bets 1/m of his fortune on each play of a game whose probability is 1/2. He tries again and again, each time staking 1/m of what he possesses. After 2 n rounds, he has won n times and lost n times. What is his result?

I’ll leave it to the reader to work out the result, but it does point out clearly that proportional betting isn’t the way to fame and fortune, at least, not if the game is fair (the payout is equal to the odds).

The section on calendars is pretty nice too, including a good description of Gauss’ method for computing calendrical dates, and including a nice nomograph that implements a perpetual calendar. Very good.

Worth having on your shelf.

For whatever reason, I have been finding it difficult to find time to blog. Perhaps it is a combination of increased amount of travel, work, or just the shorter daylight hours, but I’m finding it hard to find the muse. So, for the next little while, I thought I’d scan through my bookshelf and find some of the stranger books that I’ve acquired, and present them with little mini-reviews and hope that some discussion and inspiration occurs.

The first of these is Dan Pollino’s Build It Yourself! PVC Rocket Engine.

Okay, first the disclaimer: I haven’t ever built any of these, and don’t really know that much about them. Even without the addition of potassium nitrate, molten sugar can burn you fairly badly if you aren’t careful. Witness the bandaids on legendary hacker Jeri Ellsworth if you need more caution, but be careful: it might serve as inspiration.

For all I know, you might end up on some watchlist for buying the book as well, although I’ve flown a bunch of times with only the usual annoyances, and no fresh ones. YMMV.

Dan has a website. Sadly, it seems to be mostly their to entice you into buying his book, with relatively little “free” information, but if you follow his links page you can probably find some more information, although a disconcerting fraction of them seem to be dead links. (You might try James Yawn’s Sugar Rocket link page for more information.) The book itself is however quite good. You might be scared a tiny bit by the appearance of CAUTION! on very nearly every page of the book, but it presents all the stages of making a powerful rocket engine in very clear detail, including modelling the nozzle, the core, the igniters and the fuel. If I have a criticism, it’s that the book doesn’t present any theory or chemistry, it’s literally just a HOWTO guide for building rocket engines. It also doesn’t even try to cover the legality of making or using these rockets. But it delivers on what it promises: a clear guide that shows you how to make and test a rocket engine which is probably significantly more powerful than the ESTES rockets you might have flown as a kid.

I’m not sure I’ll ever get to building one of these, but it is fascinating.