It took me, probably, more than a year to read Beautiful Code (almost from cover to cover). Because of its volume, list of authors and coverage of languages and topics this book can absolutely be considered one of the bibles of modern programming. I've learned a lot from it and can recommend it to any programmer: both novice - to get the general picture of what programming spans and what is important in reality - and experienced - to study previously uncharted corners and maybe rethink some of the underpinnings of personal programming philosophy.
Surely, not all essays were of the same quality - on the contrary it ranged from very poor and dull, although still mostly informative, to insightful and even fascinating. The book features reknown authors: programming language designers and authors of famous books, as well as not so well-known but at times even more interesting people from various scientific and engineering communities. Almost all languages, ranging from FORTRAN to Lisp and Ruby are covered, and most of the topics are viewed, so to say, from two angles: most of the essays are paired either by language, or by topic, or both. Not surprisingly, almost half of the essays feature at least some code in C, as it was and remains the lingua franca of computing.
Each author was given a very vague task - to describe the most beautiful code, they've ever written or seen. Some interpreted it literally and just told and analysed an algorithm or hack. Others told a story about the whole system, how it evolved and became beautiful - these kinds of stories, were surely, the most interesting part of the book for me with two favorites. The first being the story of PGP-enabled Perl-based mail service Cryptonite, which maybe could feature in some collection of Cyberpunk novels; and the second - The Most Beautiful Code I Never Wrote by Jon Bentley, the author of Programming Pearls, in which he presents the analysis of Binary search algorithm, that helped to understand many aspects of this fundamental programming tool. Yet some people, who surprisingly include such famous programmers as Doug Crockford or Tim Bray, just used it to describe an idea, that they had found interesting, sometimes even without explaining why...
Personally for me the highlights of the book were:
- how extensibility and unification played an ultimate role in most of the stories about system beauty
- the proliferation of callback techniques on one hand and rather poor support of them in most of the languages on the other hand
- and the articles, emphasizing different aspects of programming craft, like Beautiful Debugging and Code in Motion (about code formatting)
I've also used a chance to dive deeper into Perl and get a glimpse of FORTRAN, as well as to learn about a lot of low-level optimization techniques and considerations.
So what's beautigul in code? I've tried to summarize the views of all authors (33 articles don't represent a statistically meaninugful sample, but still :)
Unsurprisingly, simplicity & elegance are emphasized a lot (6 times) and its backers include Brian Kernighan, Yukihiro (Matz) Matsumoto and Jon Bentley. It's also matched, or even slightly overrun in terms of proponents number by clear interface/API abstraction and code structure/organization (i.e. proper OO or functional design). Flexibility comes next with 3 people, championing it. Only 2 people root for modularity, or as the Unix philosophy goes "small pieces loosely joint", but their articles are very good and insightful: Simon PeytonJones on STM in Haskell and Greg Kroah-Hartman about the Linux Kernel driver model. Than comes a long tail of features, like: frugality (not being wasteful), being close to the low-level, balance, and visual readability. Some authors didn't emphasize any one aspect of beauty, but told about some area they thought may be beautiful. These include: search, code generation, tests, debugging, top-down operator precedence parsing, hygienic macro support and math.
P.S. And here's an alternative review by Jeff Atwood, based on the same data, but with different conclusions, which boil down to this: code per se can't be beautiful. He quotes another opinion:
The chapter written by Yukihiro Matsumoto, the creator of Ruby, was the most impressive standout. It is three pages in which he simply writes about what he believes beautiful code is. He explains his understanding of beautiful code to you. This is what the book should be!
While provoking interesting thoughts and discussion, those three pages weren't enough: they were quite shallow and didn't bring enough useful evidence to the table. The best chapters did both, and there are quite a few in the book.