I programmed in TypeScript like in Haskell (Lazy Evaluation) 

Please bring HaskellRank back! I was a really cool series

A great demonstration of the sheer power of vim

I was honestly not prepared for this level of memery

It's funny, Idris -- which is in large parts based on Haskell -- forewent lazy evaluation in part because it made it unclear whether lists were infinite or not. Instead, it marks infinite and lazy types explicitly, while still allowing for Haskell's nice parenthesis-free calling semantics.

3:17 kinda cucumbersome

Greatest thing I've seen in like 20 days of funemployed researching

Minor quibble, but this needed more commentary about memoization. Repeated evaluations of a lazy value in these examples would result in re-evaluation of the computation. In Haskell, this doesn't happen, because the first attempt to evaluate it locks in the evaluated value for all future calls -- even if you share that lazy value out _before_ you force it -- ie, all references to the shared value share the forcing. It won't ultimately remove the dangers of 'thunk buildup' like you had with begin() in the range function, but it often can remove the situations in which it's a problem, and the inefficiencies in _not_ having memoization can put a damper on using this useful style. It may not be the main thing you wanted to talk about, but with the comparisons with Haskell, this is a nontrivial difference. (And one that _could_ probably be authored in TypeScript). Otherwise you're not _quite_ getting 'the full Haskell experience'. That said, this was a pretty nice talk!

1:11:30 Yesssss, I was *hoping* that the punchline was going to be Sieve of Eratosthenes ... Such a classic / nice example ... So satisfying!

Great video tzozin. You're making the most interesting technology related content on the internet right now imo. Keep it up 😘

I wish this video and the json parser one was edited down to like 10-20 minutes so I could show other people without asking them to watch an hour and a half video :(

this is why I love computer science. thanks for this university level class, tsogod.

Very nice video. As RU-vidr and educator myself I can appreciate how you've done all of this.

54:00 Re: Haskell fanatics: You're absolutely right. Trying to 'debug' performance problems in a lazy language is mind-bendingly difficult -- anything that you do to investigate, while it won't change input -> output mapping, *may* change what gets evaluated and when. If you want to checkmate a Haskell fanatic's 'silver-bullet' arguments, ask them why `seq` exists.

Русский акцент ни с чем не спутаешь)) Спасибо за видео.

So, this is really call-by-name, rather than lazy evaluation -- things are evaluated only when needed ... but may be evaluated repeatedly. Also, your intuition that thunks are not used to implement this is generally right; traditionally, graph reduction has been used ... afaik, modern GHC uses some more-sophisticated abstract machine (It was STG at some point, but I'm not sure what's being used now.).

Liked instantly for using deno.

I wish there was an alternate universe where tsoding was by Dad and I will sit by his side and learn programming hahaha. Love your videos Dad

Amazing! Also, I would recommend some if/else clean up, the code will look more impressive. You don't need an "else" if the function returns. A lot of indentation will change, the source code will be more readable. But I love it! Thank You!

The method that called panic was unwrap which if None in Rust will panic. The developer haven't taken care of the outcome None. Cool video btw :)

3:17 Am I the only one who hears "cucumbersome" at this point?

Nice, now i do have a new video for my next few toilet visits, thanks xD

"I programmed in TypeScript like in Haskell (Lazy Evaluation)" == *I skated on my skateboard like a Lamborghini (Acceleration)*

tsodin, TS - typescrypt, Oding - god of wisdom. Tsoding - God coding, God of coding confirmed.

It would be cool to have keywords effect/do what are to () => a what async/await is to Promise

Keep in mind that all of the code was written using Deno v0.31.0. Things may change in the future versions and the code may stop working. For the latest version of the code examples please visit: github.com/tsoding/lazy If something doesn't work in the latest examples feel free to report an issue or submit a Pull Request.

hung, you are a great human!

in js you can use spread operator to call the rest on an array let [head, ...tail] = [1,2,3,4,5] head = 1 tail = [2,3,4,5]

still my fav video

I love this, you just gained another subscriber! thanks

In short-circuit evaluation. We can do just a() && b()

This is fun to watch, eventho it hurts my brain ! :P

Why do people who come from Java / OO use `T` as the first type parameter? In functional languages (Haskell, SML, etc.) we start with `A` ... which seems like the obvious place to start.

Can you make a serie of videos where you make haskell rank challenges without any built in function? only pure functional and haskell concepts like pattern matching or list comprehension? Thanks for your content, it's amazing! (:

Great video! I hope that you do some more fp in Typescript again!

thanks for upload this video, I miss the streaming that day :(

I'm confused why one would bother with taking a slice of an infinite lazy list as opposed to just... calling a function. If lazy values essentially are functions, why even make the distinction? You could just make a structure {start, length, fn} that when parsed will generate your list {1, 10, n => n * n} -> [1, 4, 9, 16, 25, 36, 49, 64, 81, 100]

37:54 array destruction

32:30 turing complete type system

1. Sincerely thank you for showing me how deno works and how great it is 2. -Ternary operator ?: shortcircuits too-

RxJs - Reactive Extensions for Javascript, also have lazy behavior baked in - Would you show some example in RxJs too? In Novosibirsk people have much time to reason about programming concepts!^_^!

47:42 I had the same problem. The stack can overflow if you store too many values because it isn't about how many levels deep, its about each of those levels adding to the stack, or in this case, one big level adding to the stack

can you do same thing with js doc?

Thank youu

I don't think you need to make return type Lazy - only arguments should suffice. Was there a specific reason you chose to wrap all return statements in lambdas as well - that seemed redundant? (This is in reference to lazySum and lazyFirst)

1:18:04 javascript nor typescript even use semicolons, lol. (that said there's very rare edge cases where you could need one)

Everything will work great with the compose implementation in JS.

"If it compiles it works" is not the point of rust. If it compiles, it's guaranteed to be memory safe, except if you explicitly tell it to ignore memory safety checks. Of course having your program guaranteed not to segfault will probably force you to write better code.

Following the code with deno I was systematically getting an "Object is possibly 'null'" error on the LazyList part... Edit 0: It seems that when I let the autocomplete use Optional Chaining it does work...

Have you ever considered using ReasonML?

very interesting! thank you. btw you should use undefined type instead of null in Typescript i think!

This whole video should be wrapped in a function

TSoding

that was awesome.

Ай маст сэй ай рили энджой йё контент

Блин, красавчик - шикарный английский.

thanks for this

42:30 It's almost unreasonable how many good ideas there have been in functional languages that have been 'soaked up' by normie languages ... Wonder if dysfunctional (?) / nonfunctional (?) people will ever 'do the induction' and realise that we ought to replace all of the derpy OO / procedural languages with functional ones ...

1:01:49 how dare you bash my cult!

I'm 3 years late to the party, but this was a great video! I'm just not sure how to apply what I just learned. What advantage does this give over traditional approaches (like using loops)? I can see that it has the potential to be more memory efficient since we're not storing an entire datastructure in memory. What other benefits are there and would you ever use this pattern in more procedural languages?

Generators inJavaScript are perfect for lazy evaluation

I think you ran demo on top of itself or something make it crash like that... and i thought in rust unwrap is when you want it to crash and burn since something is really wrong. but here i think it was Options args that made it crash, strange... they didn't handle it "gracefully"

very interesting video, but I wonder why your chat shit on every language other than haskell, like the the rust error at the beggining, it is a voluntarry error from the devs (you can see it because the unwrap method is being called on a result type, which means "if this is an error just crash the program"), and yes javascript has it flaws but I don't think programming complex web applications UI is better in haskell

"It is not a tarball" - tsoding

"I don't understand why you need all these shell scripts". Javascript developers man, javascript developers. npm install pad-left. They're not terribly sane.

cucumbersome

1:21:55 You just got a bigger prime number by typing some random digits, than the one You wanted to test... xD

17:20 Wait ... are there still people who believe that static typing isn't the obvious / only choice!?

51:44 will be back later.

comfy

Isn't lazy of lazy is same as regular lazy? Like in typescript notation: Lazy is same as Lazy ?

If your goal is to write unreadable / unmaintainable code, then you have accomplished that. Why do functional programmers abstract / genericize their code so much that the specifics of what a function is actually doing is lost. It is like abstracting all of your code to Func. This is code only a mathematician would love...and code that every application developer would hate. Some people are too smart for their own good.

Я знаю, братик, только на стримы не ходил =)

Anyone else want to just hug Alexey?

Instant like, for using duck duck go

your voice sounds like Life of Boris

Хорошая попытка, но на 91к сито уходит в переполнение стека. Мои соболезнования. Надеюсь, когда-нибудь оно станет по настоящему бесконечным

"A SINGLE EXECUTBLE! WHY NODEJS IS NOT LIKE THAT?"

You should check out ramda.js

deno it's not node JS !

when you want to put lambda calculus into javascript

Hi Tsoding, would you mind to share how to be a great coder like you? :smile:

you speak with strong soviet accent comrade

Hey man! You are a GOD! I want to recommend you fp-ts. This is an awesome library for FP. I would love to see some content from you using this library. github.com/gcanti/fp-ts

The error happened because someone used unwrap. Like, why use Rust if you are going to unsafely unwrap the Options?

5:30 Dude you can literally do the same with node. Its just the second link on downloads page and not the first one xd

this is not a silver bullet

let's hang out

most of this can be done with js (es6) , without the types

Deno has too much crap packed into it. That’s something that is going to change they’re going to first add more and later take away. And that in a nutshell is why.

1:11:25 Yes, because you should say "what is it called", not "how is it called", of course unless you forget how to use your mouth to make a sequence of sounds which many people would interpret as that word you're trying to pronounce.