This was the clearest, most understandable introduction to lambda calculus I'm come across. Nicely done. Thanks for making it.

This is hands down the best intro to functional programming/lambda calculus out there. The fact that it only has 38k views at the time of writing is a crime of untold magnitude.

Watching this video felt like unravelling the world's deepest conspiracy

the best lambda calculus explanation ever

Just want to say, those were some of the best slides I've ever seen.

I used to teach at a fullstack bootcamp and I'm completely blown away by the quality of this lecture. Feel like an absolute jabroni. Amazing my dude.

This should be a TED Talk, the preparation must have been intense. You Sir are a genius

Less than seven minutes in and I can already see that this is great: clearly explained, well articulated, the works. But now I have to rush off to work, writing lambda expressions in Java.

This lecture is just unbelievably good. This guy is a very talented teacher/lecturer

Literally the best talk about lambda calculus on KZfaq, after watching this video (and the second one), I am enthusiastic to read To Mock a Mockingbird.

This was remarkably clear, a lot of thought must have gone into preparing this talk ! Thank you so much for this excellent talk : )

Beautiful talk! I love the way you tie it into javascript, the one functional language that everyone understands!

[0:00:00] Intro [0:00:48] I = a => a [0:01:48] Notation [0:06:39] Functions [0:09:15] Beta-reduction [0:11:49] M = f => f(f) [0:15:04] "n-ary" shorthand [0:17:00] K = a => b => a [0:18:44] KI = a => b => b [0:20:49] History [0:29:30] Combinators? [0:31:00] C = f => a => b => f(b)(a) [0:33:46] T = K; F = KI [0:39:53] not = p => p(F)(T) [0:42:21] not == C && not !== C [0:45:30] and = p => q => p(q)(p) [0:48:39] or = p => q => p(p)(q) [0:49:29] or == M [0:51:41] beq = p => q => p(q)(not(q)) [0:54:19] ¬(P ∧ Q) === (¬P) ∨ (¬Q) [0:55:01] Closing [0:56:48] Basis [0:58:15] WHY? [1:00:37] Y- and Z-Combinators [1:01:58] Outro

I’m a long time software engineer. Have been focusing on functional javascript the last couple years. Have been trying to put my finger on why functional feels so much better than other methods. This video and others like it get at it. Functional programming connects to underlying fundamentals such as the lambda calculus and category theory. Fundamentals which transcend a particular language. Functional programming feels like performed art. It’s satisfying again. Symmetrical, elegant, mathematical. I can tell the presenter *feels* the beauty of the lambda calculus too. Thanks for sharing!

This just opened a whole new world to my mind. I can't thank you enough for making and posting this. You can't possibly know how deep my thanks are to the presenter, the staff, and all other associated people. Keep doing what your doing, and you'll find someone will change the world because of your work. Thank you, and bless you all.

On the bit about XOR or equality (@52:35): On booleans, *not*-equal is the same as XOR. We have && and || operators for AND and OR, but nothing for XOR... except you can use != for that. I also thought it was XOR at first, because I noticed the functions behavior was to return either q or !q, depending on p, it's just that XOR returns !q when p is true, and q when p is false, while equality does the opposite.

Mr. Lebec’s talk was excellent. If I had the desire to return to professional programming, I would be knocking at your door.

Great Work. Both the thoughts and the slide deck. Amazing!

Such a great explanation of lambda calculus that I was so confused about -- thank you!

Very helpful on my path to understanding functional programming. If you make any more related vid's I'd like to know.

Very helpful! Thanks for the talk.

Thank you for this talk, insanely good and fun!

This is so engaging! Thank you!

Great video. Easy to understand, the idea to translate lambda into fat arrow functions works perfectly for me... I'm going to spend the rest of the evening playing around with the nodejs prompt. Great video!

53:02 *that's XNOR !*

This presentation blew my mind. Awesome stuff!

Excellet introduction! I knew nothing, (despite watching another video by which I was more confused than enlightened) now things are much clearer, bravo!

thanks so much. for a newbie to understand this, is remarkable on your part.

Great tutorials on functional programming. Thank you!

Brilliant presentation. I can see why Gabriel said he spent a long time making it.

I'm half way through this, just wanted to praise the speaker and the talk, real quality, perfect for my entry-level FP disposition.

Well done - fantastic lecture - best explanation of lambda calculus I came across so far!

This is the most amazing explanation of Lambda Calculus I have come across! Thank You !

I liked how nicely this video was placed in the left bottom corner so I can't see was the lecturer is typing. Good job!

Best explanation on the internet

Thank you so much, I had no luck understanding beta reduction but you made it so clear with such complex example.

Amazing! It seems so simple.

Hands down one of the most clear and concise videos I've seen introducing basic concepts of Lambda Calculus. Gabrial's excitement pretty much forced me to crack open a REPL and follow along. I'll now be locked away composing combinators for a very long time. It's also so painfully obvious how this subject can help to write more clean, readable, and declarative code. Great Job on this one. Part two blew my mind! The more I try to "play" with these combinators, the more I see the need for FP data structures. If anyone has any recommendations for similar talks, specifically on Lambda Calc within Javascript, I'd really like to see more on the subject! :D

Best video on Lambda Calculus ever. Got to know about the combinatorial logic for the first time so clearly. Thank you. 🙏👍🏽

You can see his passion. Great work.

This was a really good presentation, informative, easy to listen to and with some humor. You did a really good job at helping me understand this stuff, thanks for that.

38 minutes into the talk and can't resist to appreciate. Very well explained

I am impressed. Math is so beatiful! Thanks for an awesome talk.

Thank you so much. This is the best KZfaq video on the topic. I was lost in the sauce until I watched this

first time in life that i can understand why lambda calculus are so amazing :D congratulations

Excellent presentation, Thank you very much

That was an amazing talk, thank you!

What an amazing speaker and so much content to revisit. I love this video.

This probably just saved my midterm grade, 10000x more clear than anything my professor has ever said. Also, this dude looks like the Jeff Winger of logical mathematics

This video is very helpful and understandable!!!Thanks!

I finally get how much you need to know and understand to start contemplating creating a start-up company.

It is strange how simple concept is it, but yet I could not easily adjust my brain to that level of abstraction.

This is amazing! Thanks!

Thanks for the great presentation!

Great explanation!

Thank you for placing the video of the speaker over what he types. It really helps. /s

Such a clear talk. Thank you.

Mr. Lebec, thank you very much for this material of yours. I will do my best to digest this to the best of my intellectual ability.

This is absolutely fascinating. Thanks!

phenomenal lecturer

Clearly clearest explanation on YT

Loved the presentation. This guy really knows how! :D

Remarkable, this is the video recommended by my professor

What a beautiful talk....

Neat, thank you for your effort.

so clear explained and slide are just artwork

This is just beautiful and amazing!

This is an excellent talk. Thank you so much 😊😊

The prettiest slides I have ever seen. edit: also some of the most engaging math/programming teaching I have ever been privy to!

I was very skeptical at first but it turned out to be well worth the watch

Wonderful talk!!! Many thanks!

It is so hard to teach this subject, excellent job

Best explanation yet from a high school student perspective thank you :)

This is amazingly good. I'm just blown away.

Great talk, thanks!

Amazing talk. Thank you.

Thank you for this video!

Absolutely beautiful 10/10 Would watch it again

Thank you very much Sir. this inspired me to keep on studying Lambda Calculus although i'm over the hill.

Beta-normal form are shown not to be calculated in general form already in the 30:th by Entscheidungsproblem presented as one of many problems by D. Hilbert in 1928. In 1936 A. Church and A Turing showed independently with Lambda Calculus and Turing Machine that it was not possible to make a program that could decide if a program was decidable. It is called Church-Turing thesis. This is fun reading: en.wikipedia.org/wiki/Entscheidungsproblem

I stumbled across this a couple years ago and struggled to find it again for the longest time. I ended up randomly stumbling across To Mock A Mockingbird and managed to find my way back to this again. Genuinely recommend this as the beginning point for lambda calculus/function programming. Does anyone have any recommendations for what to learn after this

Great and fun explanation, thank you very much

Great video, preparation, delivery, ...

Thankyou so much for the lecture.

Amazing, you are a great lecturer.

This guy does everything right. Also love his use of PowerPoint

omg~ to understand this lecture, I study hard english! worth it! Thank you.

Excellent indeed, Thank you !

Excellent presentation. By the way, at 52:40, it's not the XOR(=exclusive-or)-function, but the negation of the XOR.

An excelent talk!

The enthusiasm is intoxicating.

Super cool, thanks a lot!

1000x better than university professor's explanation

very clear ad thanks for the heads up on 'to mock a mockingbird.' It's on my x-mas list.

The best video on λcalc‼️‼️

This is fantastic!

extraordinary

A great talk fun and truly informative.

Awesome, man! Just awesome!