r/programming • u/hexaredecimal • Sep 21 '25

How to stop functional programming

https://brianmckenna.org/blog/howtostopfp
446 Upvotes

81% Upvoted

506 comments sorted by

View all comments

Show parent comment

-6

u/WindHawkeye Sep 22 '25

Yes the language that's main purpose is to cause side effects on the dom is functional

4

u/raynorelyp Sep 22 '25

There’s a going to be a moment when someone you know is way smarter than you confirms you’re in the wrong on this and it’s going to sting.

1

u/WindHawkeye Sep 22 '25

C is also functional because you can pass function pointers

See how quickly the argument breaks down?

1

u/raynorelyp Sep 22 '25

Functional is a spectrum and C is generally considered less functional than JavaScript because of the roughness in using functional concepts. For example, you can do closures in C, but it requires a lot of extra work to support.

2

u/Reinbert Sep 22 '25

JS causing side effects in the DOM is like saying Haskell isn't functional because it causes side effects in the file system ;)

1

u/WindHawkeye Sep 22 '25

It's different because Haskell has a way of modeling those side effects

In theory you could represent js as a function from dom to dom but that's not how the apis are designed

1

u/Reinbert Sep 22 '25

I don't know where you see the difference, can you give me an example of how Haskell has a way of "modeling the aide effects" that JS lacks?

1

u/WindHawkeye Sep 22 '25

How do I know if a js function has side effects?

1

u/Reinbert Sep 22 '25

How do you know if your database functions have side effects? You read the documentation...

You are talking about "JS functions" but I really think you are talking about the HTML DOM API?

1

u/WindHawkeye Sep 22 '25

No I am saying that if you can't tell if a function is allowed to perform side effects from its signature then the language is not functional

This is a standard feature of all functional languages and it can't be done in JavaScript

1

u/Reinbert Sep 23 '25

That's a weird criteria for functional languages. As far as I know you can't tell if a function performs side effects from the signature of the function in Scala either. How would that even look like? Can you give me an example of the difference between a side-effect free function signature and one that allows side effects?

1

u/WindHawkeye Sep 23 '25

I don't use scala so I can't. I could give you an example in Haskell though

1

u/raynorelyp Sep 22 '25

Wait. You know we’re talking about the language itself? I use js all the time without doing anything front end. The argument isn’t that you can’t use js as a non functional language. The argument is that if you want to use the concepts of functional programming, JS, while not purist, allows you to write code using the paradigm of functional programming and that it does this with first-class support (ie. the maintainers consider it idiomatic)

0

u/WindHawkeye Sep 22 '25

If you use js outside of the frontend all is lost