![](https://midwest.social/pictrs/image/866e62bf-05eb-4781-abb2-f9dd9597a745.gif)
![](https://programming.dev/pictrs/image/170721ad-9010-470f-a4a4-ead95f51f13b.png)
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::<u32>().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<u32> = text
.lines()
.next()
.ok_or(anyhow!("No first line!"))?
.split_whitespace()
.skip(1)
.map(str::parse)
.collect::<Result<_, _>>()?;
println!("seeds: {:?}", seeds);
Ok(())
}
If you’re writing code that generic, why wouldn’t you want
str
to be passed in? For example,Counter('hello')
is perfectly valid and useful. OTOH,average_length('hello')
would always be1
and not be useful. OTOOH, maybe there’s a valid reason for someone to do that. If I’ve got a list of items of various types and want to find the highest average length, I’d want to domax(map(average_length, items))
and not have that blow up just because there’s a string in there that I know will have an average length of1
.So this all depends on the specifics of the function you’re writing at the time. If you’re really sure that someone shouldn’t be passing in a
str
, I’d probably raise aValueError
or a warning, but only if you’re really sure. For the most part, I’d just use appropriate type hints and embrace the phrase “we’re all consenting adults here”.