Ruby Conf 12 - Y Not- Adventures in Functional Programming by Jim Weirich
Why Hacker News recommends it
HN recommends it repeatedly as one of the best and most entertaining programming talks, and as the talk that makes the Y combinator click, even for people who do not use Ruby.
What it is
Jim Weirich's RubyConf 2012 talk derives the Y combinator step by step, live-coding in Ruby lambdas. It builds up an understanding of functional programming and lambda calculus from first principles.
Recommended by 17 HN commenters across 18 different months, 2013 to 2026.
What Hacker News said
Strong rec mekishizufu · 2013-11 · on “What is a y-combinator? (2008)”
If you are curious about the topic, I strongly recommend watching these videos: Y Not- Adventures in Functional Programming by Jim Weirich [this video] Programming with Nothing by Tom Stuart [LINK]
Strong rec VeejayRampay · 2014-02 · on “So very sad to hear about the passing of Ruby legend Jim Weirich”
[this video] This talk is a must-see, really shows off Jim Weirich's craft and overall ability to be a great pedagogue.
Strong rec careersuicide · 2015-11 · on “Writing code doesn't mix well with oration”
Jim Weirich's "Y Not - Adventures in Functional Programming"[1] is perhaps the most entertaining and interesting technical talk I've ever seen. It would absolutely not be as cool or as fun without the live coding. Additionally, the incremental process by which he arrives at the conclusion makes the topic much more approachable. 1. [this video]
Strong rec JamilD · 2016-12 · on “What is a Y Combinator?”
For those (like me) that prefer learning through talks and demonstrations, Jim Wierich gave an incredible talk on the Y Combinator at RubyConf 2012. Video: [this video] Code: [LINK]
Strong rec webdevatlurk · 2018-04 · on “Ask HN: What is your favourite tech talk?”
Finally made an account to post in this thread. I'm rather early in my career doing mostly Ruby, Python and JavaScript things. As you might expect, I consume mainly Ruby, Python and JavaScript related talks. The first two talks that really blew my mind are: - K Lars Lohn's PyCon Keynote from 2016: [LINK] - Jim Weirich's (RIP) "Y Not" talk from RubyConf 2012: [this video] There are many other presenters who I have a good opinion of: - Raymond Hettinger: his presentation/teaching style is something I'd like to model my own after, also he gave the first talk on writing proper threaded/concurrent python that I was able to understand and make use of. - Brandon Rhoades: another speaker with a presentat
Strong rec dmvaldman · 2018-05 · on “Y Not? – Adventures in Functional Programming (2012)”
This video (similar lecture, different audience) has the slides alongside the talk: [this video] Still one of the best programming talks I've ever seen.
Strong rec caseyohara · 2020-09 · on “All you need is λ, part one: booleans”
On the same topic, Jim Weirich's 2012 talk "Y Not - Adventures in Functional Programming" on lambda calculus and the (little 'c') Y combinator is fantastic. [this video]
Strong rec sva_ · 2025-04 · on “Baking the Y Combinator from Scratch”
If anyone wants this in a humorous 1 hour format, watch the legendary Jim Weirich (rip) explain it here: [this video] Don't be discouraged that it is in Ruby as the concepts are completely general. Great watch even though I never coded a line of Ruby.