Comment by alister | Hacker News Reader

Comment by alister | Hacker News Reader

Reading code just for fun was a thing in the early and mid years of UNIX (eg., 7th edition or System V). People eagerly passed around faint 10th generation photocopies of Lion's printout of and commentary[1] on the UNIX source code. The annual USENIX conference had a popular short course in which they went through the entire UNIX kernel line by line. Why was that a thing back then and not now? Certainly UNIX was an amazing piece of work, but there are amazing works today -- the modern browser for example.

I think that the difference is that the totality of the UNIX kernel was comprehensible for a single mind. The UNIX kernel in 1983 was less than 20,000 lines of code, almost all in C, and more than 75% was not machine-dependent.[2] The amazing software of today, something worthy of reading for fun, is literally millions of lines of code, written in multiple languages you don't know, and evolving so fast that whatever you read might be completely different a few months later. There's no joy in knowing a tiny part of that. It would be like reading 10 pages from the middle of a novel, a novel so big that you know you'll never finish it.

[1] https://en.wikipedia.org/wiki/Lions%27_Commentary_on_UNIX_6t...

[2] https://en.wikipedia.org/wiki/History_of_Unix#1980s

I learned yesterday that Ken Thompson used to host readings of Unix source code at Berkeley where they would go through the code line-by-line (https://www.salon.com/2000/05/16/chapter_2_part_one/): >And from the very beginning, Unix benefited from a communal vibe that spread directly from its creators, Ritchie and Thompson. > > Fabry recalls grasping the hidden wonders of Unix one week in 1975 when Thompson conducted a "reading" of Unix over several successive nights. > >"The first meeting of the West Coast Unix User's Group had about 12 or 15 people," recalls Fabry, a mild man, now 60 years old, who clearly delights in his 25-year-old memories. "We all sat around in Cory Hall and Ken Thompson read code with us. We went through the kernel* line by line in a series of evening meetings; he just explained what everything did ... It was wonderful."

This is still done today, just with other software.

I've read blog posts that go through the entire redux javascript library line by line, or review an entire chunk of React.

Even just yesterday here on HN was a submission that just contained shaders from Wolfenstein.

There's a category of articles out there nowadays that do "$library in $num lines of code", reducing popular libraries or frameworks down to their core - filtering out all the edge cases, so to speak. I've seen them for Angular, React, Redux, etc. I think that a lot of frameworks and libraries would do good to have a "core" codebase somewhere, something pure but unoptimized and without edge cases that are easily digestable, that explain the core idea of it.

Do you mind linking me to the React one? I was unable to find it, but maybe my Google-fu is just not good today.

I wonder if part of the reason this worked so well is that the Unix kernel was written in a fairly straightfoward top down style? It's a lot harder to do a code reading if you're hitting different abstractions on every other line and having to make digressions to track down exactly what that abstraction is doing.

I suspect in a lot of cases reading the Lions commentaries was not purely for fun. The original audience (Lions' students) were doing it as part of their university course. Many of the contemporary readers would have been reading it because they needed to understand, fix bugs or add features to their unix systems (I think one of the introductions in the reprint book is from somebody who was in this position). But you're right I'm sure that the the key was the combination of (a) real world and genuinely useful code that the readers were using (b) size such that you could realistically understand all of it (c) excellent accompanying code commentary.

I read through the Lions book in the late 1990s when the reprint came out, essentially "just for fun" -- it remains probably the only sizeable piece of code I've read for fun.

Is there any material around still from the USENIX course that went through UNIX line by line?

It looks like the Lions commentary also does that to a certain extent as well. There's even a version of the book online [0].

[0] http://www.lemis.com/grog/Documentation/Lions/index.php

I'm a younger developer and I had never heard of Lions' Commentary. It sounds amazing and I'll order a copy, but is there a more updated version or a similar book out there that may be more relevant?

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