Since this comment gained traction, here are some better examples of what I meant by dumbledore's office:

A romp through approaches to generative adversarial networks described as if they are realms in a Tolkein world. https://news.ycombinator.com/item?id=20251308

(This week's) complete guide to building a terminal text editor from scratch in C which gently holds your hand at each step: https://news.ycombinator.com/item?id=14046446

Stumbling down the root domain of the above link leads you to the collected archive of _why_the_lucky_stiff, a hacker artist who created technical documentation as if it were a work of literature, animating and writing songs about ruby in a unique aesop meets kaftka meets neutral milk hotel style, and who then suddenly disappeared and deleted his whole internet persona, transmitting a 96-page oblique missive years later as individual PCL files. https://viewsourcecode.org/why/

Someone documents how using the 30+ year old, tiny awk language let him do what all the latest fad big data tools couldn't https://news.ycombinator.com/item?id=20293579

Several posts this past week from natashenka's Project Zero blog led me to her passion project of being the world's leading expert in hacking tamagutchis, which read as part instructional and part love letter to digital pets http://natashenka.ca/

Even though I'm ostensibly in the same industry as retail brokerages, I've never understood their business models as well as I did when I read this thread https://news.ycombinator.com/item?id=20276551

Not to keep going, but just to have a less lame example than a couple introductory textbooks -- I didn't mean to imply HN as a surrogate class syllabus

I did a startup solving this problem (yet again) in an APL; we sucked at enterprise sales, but our data structures went rather faster than BTrDB. The most famous example of solving this problem being Kx systems. Less famous, but basically using the same ideas (these guys all worked with Art and the Iversons): http://marketgridsystems.com/

And no, I won't explain it in detail. I consider the spark team basically cretins, and it would ruin several of my pals businesses while transferring wealth to hedge funds, exchanges and advertising groups making solutions to this problem available for free. I'll continue to snigger up my sleeve at the fact that decades of open source development still haven't noticed things which were obvious in the 1960s.

Edit add: a great example of this kind of thing, if not this exact thing: some poor guy trying to solve a 25tb problem using spark, parquet files ... finally solving it with ... Awk. Old tools written when 1mb was a lot of memory; sed, awk, tr, cut: vastly better than new tools.

https://news.ycombinator.com/item?id=20293579