Deriving the Y Combinator in JavaScript

#1

Post by shamdasani » Thu, Jul 05, 2018, 10:19 PM UTC

Deriving the Y Combinator in JavaScript
enlight.nyc

Re: Deriving the Y Combinator in JavaScript

#2

Post by [deleted] » Thu, Jul 05, 2018, 11:55 PM UTC

[deleted]

Re: Deriving the Y Combinator in JavaScript

#3

Post by 18nleung » Fri, Jul 06, 2018, 12:09 AM UTC

Hi! Author here, and glad to see my writeup on HN.

I’m a JS developer by trade, but I’ve recently started exploring FP/Haskell and came across the Y Combinator. The Y writeups currently online that I read were wonderful for a seasoned Haskell programmer, but I thought it would be great to explore the concept from a more FP beginner-friendly lens, and through a more familiar language - JavaScript.

I hope this exploration is helpful, and feel free to leave any questions or comments you may have below!

Re: Deriving the Y Combinator in JavaScript

#4

Post by Retra » Fri, Jul 06, 2018, 12:13 AM UTC

Of course, if your language doesn't support recursion it probably doesn't have first-class functions either. It's pretty trivial to implement recursion if you can pass a function pointer around.

Re: Deriving the Y Combinator in JavaScript

#5

Post by jacobwilliamroy » Fri, Jul 06, 2018, 12:17 AM UTC

18nleung wrote: post #3

Hi! Author here, and glad to see my writeup on HN. I’m a JS developer by trade, but I’ve recently started exploring FP/Haskell and came across the Y Combinator. The Y writeups currently online that I read were wonderful for a seasoned Haskell programmer, but I thought it would be great to explore the concept from a more FP beginner-friendly lens, and through a more familiar language - JavaScript. I hope this explorat…

Is it impossible to write a y-combinator with space complexity O(1)? I'm in the very early stages of a comp/sci education and have not yet learned how to prove that something is impossible.

Re: Deriving the Y Combinator in JavaScript

#6

Post by dnsco » Fri, Jul 06, 2018, 12:25 AM UTC

Jim Weirich's 2012 Ruby Conf talk is also a great introduction to the Y Combinator and Lambda Calculus.

https://www.youtube.com/watch?v=FITJMJjASUs

Re: Deriving the Y Combinator in JavaScript

#7

Post by mchahn » Fri, Jul 06, 2018, 12:30 AM UTC

Maybe a stupid question ...

Isn't passing a function to itself kind of like recursion?

Re: Deriving the Y Combinator in JavaScript

#8

Post by [deleted] » Fri, Jul 06, 2018, 12:31 AM UTC

[deleted]

Re: Deriving the Y Combinator in JavaScript

#9

Post by rs86 » Fri, Jul 06, 2018, 12:31 AM UTC

mchahn wrote: post #7

Maybe a stupid question ... Isn't passing a function to itself kind of like recursion?

no, it's more like passing a continuation in this case (which is the function itself). but the function is not defined in terms of itself.

Re: Deriving the Y Combinator in JavaScript

#10

Post by nv-vn » Fri, Jul 06, 2018, 12:32 AM UTC

18nleung wrote: post #3

Hi! Author here, and glad to see my writeup on HN. I’m a JS developer by trade, but I’ve recently started exploring FP/Haskell and came across the Y Combinator. The Y writeups currently online that I read were wonderful for a seasoned Haskell programmer, but I thought it would be great to explore the concept from a more FP beginner-friendly lens, and through a more familiar language - JavaScript. I hope this explorat…

Hey dude! Not sure if you remember me but I talked to you a while ago on a2c. Anyways, this is a cool article and I thought you did a good job of explaining some of the technical details. Btw, since you have a JS background I thought I'd recommend ReasonML to you. I just started using it, but I think it's a really nice mix of functional programming with JS type stuff, plus it's designed by the guy who made React.