for_each_count

Extremely simple crate providing an extension trait for the standard [Iterator] trait with two utility methods:

• for_each_count: Similar to for_each() but returns the count of processed elements
• try_for_each_count: Similar to try_for_each() but returns the count of processed elements in the [Ok] case.

Both methods solve the common[^2] use case of applying a transformation to iterator elements and then returning the length of the iterator. While this is trivial to achieve using the standard methods[^1], I find these extension methods to be more ergonomic, and they are available in the big extension crates, like Itertools.

The provided extension methods try to mimic the way they'd be likely implemented in core: based on fold() and try_fold(). This seems to be the preferred strategy in the standard library. for_each(), try_for_each() and count() are all implemented like this at this time.

[^1]: Like using [Iterator::inspect], or [Iterator::map] and [Iterator::count], or keeping a mutable count outside the closure passed to for_each. [^2]: Maybe not that common, but I've needed it a couple of times. Other people too.

Examples

use for_each_count::IteratorForEachCount;

let mut sum = 0;
let count = (1..=5).for_each_count(|x| sum += x);
assert_eq!(count, 5);
assert_eq!(sum, 15);