this post was submitted on 16 Oct 2024
65 points (97.1% liked)

Rust

5949 readers
1 users here now

Welcome to the Rust community! This is a place to discuss about the Rust programming language.

Wormhole

!performance@programming.dev

Credits

  • The icon is a modified version of the official rust logo (changing the colors to a gradient and black background)

founded 1 year ago
MODERATORS
snowe@programming.dev
Ategon@programming.dev
EdTheLegendary@programming.dev
kahnclusions@programming.dev
torcherist@programming.dev
65
What are some mind blowing Rust tricks? (programming.dev)
submitted 3 weeks ago* (last edited 3 weeks ago) by little_ferris@programming.dev to c/rust@programming.dev
52 comments fedilink hide all child comments
 

If we were to create a Rust version of this page for Haskell, what cool programming techniques would you add to it?

you are viewing a single comment's thread
view the rest of the comments
[–] tuna@discuss.tchncs.de 11 points 3 weeks ago (8 children)

Something i didnt know for a long time (even though its mentioned in the book pretty sure) is that enum discriminants work like functions

#[derive(Debug, PartialEq, Eq)]
enum Foo {
    Bar(i32),
}

let x: Vec<_> = [1, 2, 3]
    .into_iter()
    .map(Foo::Bar)
    .collect();
assert_eq!(
    x,
    vec![Foo::Bar(1), Foo::Bar(2), Foo::Bar(3)]
);

Not too crazy but its something that blew my mind when i first saw it

[–] little_ferris@programming.dev 2 points 3 weeks ago (1 children)

Yea it's like when we writeSome(2). It's not a function call but a variant of the Option enum.

[–] barsoap@lemm.ee 3 points 3 weeks ago (2 children)

Enum constructors are functions, this typechecks:

fn foo<T>() {
    let f: fn(T) -> Option<T> = Some;
}

I was a bit apprehensive because rust has like a gazillion different function types but here it seems to work like just any other language with a HM type system.

[–] little_ferris@programming.dev 2 points 3 weeks ago

Woah. That's quite interesting. I didn't know that.

[–] anton@lemmy.blahaj.zone 1 points 2 weeks ago

I was a bit apprehensive because rust has like a gazillion different function types but here it seems to work like just any other language with a HM type system.

The fn(T)->R syntax works for functions without associated data, it discards details of the implementation and works like function pointers in C. This allows them to be copy and 'static.

The other function types can have data with them and have more type information at compile time which allows them to be inlined.
These functions each have their own unwritable type that implements the function traits (Fn(T)->R, FnMut(T)->R and FnOnce(T)->R) depending on their enclosed data.

I hope I remembered everything right from this video by Jon Gjengset.

load more comments (6 replies)