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What could go wrong trying to solve AoC in Rust? (sh.itjust.works)
submitted 9 months ago* (last edited 9 months ago) by MaliciousKebab to c/[email protected]
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[–] [email protected] 46 points 9 months ago* (last edited 9 months ago) (2 children)

The collect's in the middle aren't necessary, neither is splitting by ": ". Here's a simpler version

fn main() {
    let text = "seeds: 79 14 55 13\nwhatever";
    let seeds: Vec<_> = text
        .lines()
        .next()
        .unwrap()
        .split_whitespace()
        .skip(1)
        .map(|x| x.parse::().unwrap())
        .collect();
    println!("seeds: {:?}", seeds);
}

It is simpler to bang out a [int(num) for num in text.splitlines()[0].split(' ')[1:]] in Python, but that just shows the happy path with no error handling, and does a bunch of allocations that the Rust version doesn't. You can also get slightly fancier in the Rust version by collecting into a Result for more succinct error handling if you'd like.

EDIT: Here's also a version using anyhow for error handling, and the aforementioned Result collecting:

use anyhow::{anyhow, Result};

fn main() -> Result<()> {
    let text = "seeds: 79 14 55 13\nwhatever";
    let seeds: Vec = text
        .lines()
        .next()
        .ok_or(anyhow!("No first line!"))?
        .split_whitespace()
        .skip(1)
        .map(str::parse)
        .collect::>()?;
    println!("seeds: {:?}", seeds);
    Ok(())
}
[–] MaliciousKebab 6 points 9 months ago

Yeah I was trying to do something like reading the first line by getting an iterator and just looping through the other lines normally, since first line was kind of a special case but it got messy quick. I realized halfway that my collects were redundant but couldn't really simplify it. Thanks

[–] [email protected] 2 points 9 months ago* (last edited 9 months ago)

Also, anyhow::Context provides a convenient way to turn Option and Result> into anyhow::Result

Like this:

use anyhow::Context;

// to my understanding it's better to 
// specify the types when their names 
// are the same as in prelude to improve
// readability and reduce name clashing
fn main() -> anyhow::Result<()> {
    let text = "seeds: 79 14 55 13\nwhatever";
    let seeds: Vec = text
        .lines()
        .next()
        .context("No first line!")?     // This line has changed
        .split_whitespace()
        .skip(1)
        .map(str::parse)
        .collect::>()?;
    println!("seeds: {:?}", seeds);
    Ok(())
}

Edit: line breaks