I'm looking for a way to eliminate the temporary vector allocation in this example:
fn doit<T: Iterator<Item = Result<i32, &'static str>>>(name: &str, iter: T) {
println!(
"{}: {:?}",
name,
iter.collect::<Result<Vec<_>, _>>()
.map(|v| v.into_iter().min())
);
}
fn main() {
let without_errors = vec![Ok(1), Ok(2), Ok(3)];
let with_errors = vec![Ok(1), Err("error"), Ok(2)];
doit("without errors", without_errors.into_iter());
doit("with errors", with_errors.into_iter());
}
This is a variation of the iterator with error handling theme, except that I don't want to create a collection (so collect()
doesn't quite do the job), but I want to perform further operations on the elements being iterated over.
Note that this gives the wrong result because Ok
is less than Err
:
fn doit<T: Iterator<Item = Result<i32, &'static str>>>(name: &str, iter: T) {
println!("{}: {:?}", name, iter.min());
}
It would give the right result for max()
by accident, but it would not stop iterating on the first error.