How to loop in a loopless language (Y Combinator)

[@crabbyboi9127]

I'm just going to pretend i was smart enough to understand that.

[@AByteofCode]

first lol

[@raglandasir6885]

me too

[@omkarbhale442]

Us us

[@syed--2023]

He teaches so fast that you can't even get spare time to process it.

[@ivandrofly]

Pause

[@adumont]

Yes it's very useless to teach... Sorry to say. Pausing and getting back every tenth of a sec and trying to get half a tenth of a sec... Is simply impossible. What is the "..." in your factorial lambda expression?

[@monstereugene]

im happy to report understanding half of that

[@crabbyboi9127]

lol

[@electronpie]

Damn! A half? You must be a genius then, I could only understand about a third of the thing!

[@AByteofCode]

Ey not bad :)

[@themathguy3149]

I liked the content very much, but as a bit of suggestion , it would be easier for me to understand if there would be more examples, there went a moment in the video that the ideas started piling up and the screen got too cluthered for me to get it. But anyway amazing content, expressed in a very didact manner.

[@AByteofCode]

Very interesting feedback, I'll absolutely keep that in mind!

[@zyansheep]

Kinda weird how you need different combinators for recursion depending on whether you do strict or lazy eval...

[@AByteofCode]

I do agree, and there are even more recursion combinators depending on how you wanna do it. For the Z combinator, you could swap out the f(x(x)) terms with f(\v.x(x)(v)) to avoid needing to do rec()(x-1)

[@ultrio325]

YOU HAVE NO IDEA HOW LONG I'VE WAITED FOR THIS VIDEO

[@ultrio325]

I've been trying to use numbers and booleans to try to make a conditional so that one could pass a "condition" function to check if the loop should be exited PROBLEM is I have ZERO idea how to do equality, and I can't do subtraction either

[@AByteofCode]

I mainly have fun trying to figure out stuff on my own but I'll try my best to help with some theoreticals. My main idea for predecessor (aka -1) would be to have a tuple (0, false) and then iterate on it with your numeral. If the second part of the tuple is false than just return (0, true) otherwise increment the 0 part. This would return your numeral minus 1. Then just apply that a few times to substract. I've yet to figure out equality though, so good luck with that and let me know if you find anything :)

[@MeanSoybean]

I feel like I barely understand it but not enough to remember how to construct since the video really is going way too fast for me. And I usually put x1.5 or x2 on most comsci videos and this one I didn't.

[@AByteofCode]

Sounds pretty normal. If you have any questions do be sure to ask. (Also this should be the last hyper complex video for a long time, as I've run out of math stuff to cover lol)

[@SimGunther]

@@AByteofCode With research papers, you'll never run out of math topics! 😈

[@AByteofCode]

@@SimGunther Of course there's more math stuff to cover! Just the channel is about computer science so I wanna focus back on the programming stuff

[@grivza]

Not just for you, I've studied a bit about lambda calculus and combinators and already knew about all that stuff but it was still too fast. In order to understand, you literally need to pause after every sentence and try the stuff out yourself.

[@superboy9431]

is it ok if I ask questions about what I didn't understand?

[@AByteofCode]

Don't ask to ask! Go ahead!

[@SolomonUcko]

1:11 What if it were to call itself using fact(fact)(x-1)?

[@AByteofCode]

Something like that would be a way to do it. When I was researching this video someone I talked to was hell bent on that being the only way to do it well. Simply its not the Y combinator so it didn't exactly fit the title lol

[@ai_serf]

we should also be able to apply a type/procedure that references itself for it's definition. in haskell: loop = loop main = loop

[@Oi-mj6dv]

Dude i fn love your channel. Its like fireship but better. Here you are talking about APL, looping using combinators and some crazy shit. Mega fan keep it up. Btw this is why when dealing with recursion its nice if a language supports TCO. AHEM SCHEME AHEM. That way you dont have to polute your functions

[@AByteofCode]

Thanks so much for the kind words! + I totally agree that TCO is the goat

[@magne6049]

The notation makes the video confusing. It would be better to slowly introduce only the strictly necessary notation.

[@AByteofCode]

I mean there's only one piece of notation, and most of the logic was covered in the previous video. I do agree though, everything gets so long I don't bother animating it and so quality suffers :\

[@magne6049]

@@AByteofCode Thanks for replying. I didn't see the previous video, just came across this one. So I might have lost some context. Btw, for animation, try Keynote Magic Move which will automatically make smooth animations that are particularly good at these kinds of things (transforming/iterating on equations). Then it's easier to introduce every little piece in a more stepwise fashion. Best of luck forward!

[@koalabear2]

This video is very confusing.

[@AByteofCode]

At least I'm self aware xD What part did you not understand so I can clarify?

[@koalabear2]

@@AByteofCode mostly everything. But that's my fault. It's great as an intro to lambda calculus

[@changwanpark7164]

Thanks for the quality content :D. One question, at 1:22, how did you come up with the idea that passing to it self? I mean, it works, but how does the derivation work?

[@AByteofCode]

No problem! The idea of passing it to itself wasn't originally mine so I can't answer that. Otherwise what do you mean about derivation?

[@changwanpark7164]

@@AByteofCode Oh I was just asking about how did you get that key idea of passing to itself. Anyway thanks for responding!

[@garklein8089]

we know that we need to recurse somehow. how are we going to recurse? by calling a function; a bound variable the only way to bind variables is with parameters, so now we know we need to call a parameter to recurse what should this parameter contain? it's logical for it to contain the whole function hope this made sense

[@changwanpark7164]

@@garklein8089 yes makes sense! Super thanks

[@AmitSingh-ty5hw]

one day I'll be smart enough to understand all of that

[@AByteofCode]

Its less about intelligence and more about learning Also some day I'll be better at making topics more easily understandable :)

[@Truttle1]

0:52 I am going to like this video, so I will like this video, to do that I will like this video, but in order to do that I will have to like this video, but first I need to like this video, but first I need to like this video, but first I need to…

[@AByteofCode]

Sounds about right :) The question is would this increase like count or decrease it?

[@NorbiPeti]

@@AByteofCode It would increase the like count by a half. :) There was a debate about something similar in one of the groups I'm in lol and someone pointed to Grandi's series.

[@AByteofCode]

@@NorbiPeti I'd be interested in knowing a bit more about what that debate was on, if you don't mind?

[@NorbiPeti]

@@AByteofCode Oh, actually, it was more abstract than this one. 0 = 1 - 1 + 1 - 1 + 1 ... being solved to be 0 = 1 using parentheses.

[@AByteofCode]

@@NorbiPeti oh i see

[@Rhys_1000]

how to add memory in lambda calculus

[@UJ-nt5oo]

You somehow made the situation worse with this video

[@MACAYCZ]

I really love your videos!

[@AByteofCode]

I am very glad to hear that!

[@LibreGlider]

I just wanted to learn more about monads so I could write better Rust code. 45 min later I've subbed and am on my way to watching the entire video catalogue.

[@AByteofCode]

Awesome, thank you!

[@PunmasterSTP]

I...have to take some time to wrap my brain around this.

[@AByteofCode]

Fair enough, the video wasn't as good as it could've been

[@PunmasterSTP]

@@AByteofCode Oh no, I think your video was really good. It's just the subject matter in general, and my lack of familiarity with it, that will require me to do some grappling...

[@aaravbhatt760]

Why don't programming languages such as python and js use lazy evaluation then?

[@AByteofCode]

There are pros and cons for each. (I'm gonna add this to my video ideas list) It's mainly a matter of predictability and purity. Firstly, strict evaluation means you know exactly when something will be calculated, but lazy evaluation overall performs a little bit better. The second (and most important) reason is that in lambda calculus or haskell, there are (in theory) no side effects, global variables or anything else. That means it doesn't matter when something is calculated. On the other hand, say in python you see "print('hello world')", do you completely ignore it because its return value isn't being used anywhere else? No, because its an instruction meant to do something. Since JS/PY/etc don't have baked-in concepts of purity and side effects, any function call (or even operation as they can be overwritten) could be doing something special and you don't want to miss out on that!

[@liudvikassablauskas1950]

This video is only for those already know everything in this video and even then it's tough to keep up

[@AByteofCode]

I agree this video was absolutely not my best work. Your criticism is 100% correct

[@xxedgelord420xx4]

It's the VC company that makes Hacker News.

[@AByteofCode]

Technically the truth

[@chezmemo]

Beautiful!

[@vikingthedude]

You broke me bro

[@AgnaktoreX]

Thank you so much for this short explanation. I get the picture, now I need to dive deep

[@AByteofCode]

Good luck!

[@funmath3835]

i broke my mind.

[@AByteofCode]

Sounds about right

[@mickolesmana5899]

😅

[@sanjaux]

Now this is programming

[@mr.duckie._.]

when X combinator

[@AByteofCode]

It does exist, but its not as interesting. The X combinator (in simplified terms) applies an argument to itself. In practice you don't really use it.

[@LambdaJack]

Let's see if you redeem yourself by making a better presentation.

[@AByteofCode]

Honestly I agree, this video wasn't very good. I bit off a lot more than I could chew. I'm gonna downscale complexity of future videos by a lot so that people can actually understand the stuff

[@TheThinKing]

the last chapter of the Little Schemer is the one chapter that tripped me up so thank

[@AByteofCode]

Glad it helped ;)

[@nothingtoospecial777]

Where can I learn more about this?

[@AByteofCode]

I'd recommend joining TheSTEMGamer's discord server (look up his channel its linked there) and asking the people there. They're the ones who taught me what I needed to know to make this video so I'm pretty sure they'll be helpful to you!

[@nothingtoospecial777]

@@AByteofCode Thanks.