Description
I'm not sure where to put this, as it would be a breaking change and clearly it would need something like a new epoch to make happen, but I thought it would be worth mentioning.
Most rust operations are fallible if they don't make sense, either through a panic or by returning an Option or Result. However, rand::sample has the following API:
pub fn sample<T, I, R>(rng: &mut R, iterable: I, amount: usize) -> Vec<T> where
I: IntoIterator<Item = T>,
R: Rng,
Randomly sample up to amount elements from a finite iterator.
This function will silently return less than amount if the size of I is less than amount. I would say this is very odd, and returning Option<Vec<T>> would have been a better design choice. You can imagine the confusion if you did rand::sample(rng, v, 100) but then only had 2 elements!
If it were changed to returning None if I.len() < amount then the current behavior could still be accomplished with:
rand::sample(&mut rng, vec.iter(), usize::min(amount, vec.len())).unwrap()
With the current behavior, user has to put guards around their code (which is not required by the compiler) to prevent getting less than amount, which is unusual in rust.